Programs & Examples On #Nsattributedstring

NSAttributedString objects manage character strings and associated sets of attributes (for example, font and kerning) that apply to individual characters or ranges of characters in the string. An association of characters and their attributes is called an attributed string.

Bold & Non-Bold Text In A Single UILabel?

Use the below code. I hope it help for you.

NSString *needToChangeStr=@"BOOK";
NSString *display_string=[NSString stringWithFormat:@"This is %@",book];

NSMutableAttributedString *attri_str=[[NSMutableAttributedString alloc]initWithString:display_string];

int begin=[display_string length]-[needToChangeStr length];
int end=[needToChangeStr length];


[attri_str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"HelveticaNeue-Bold" size:30] range:NSMakeRange(begin, end)];

How can I make a clickable link in an NSAttributedString?

The heart of my question was that I wanted to be able to create clickable links in text views/fields/labels without having to write custom code to manipulate the text and add the links. I wanted it to be data-driven.

I finally figured out how to do it. The issue is that IB doesn't honor embedded links.

Furthermore, the iOS version of NSAttributedString doesn't let you initialize an attributed string from an RTF file. The OS X version of NSAttributedString does have an initializer that takes an RTF file as input.

NSAttributedString conforms to the NSCoding protocol, so you can convert it to/from NSData

I created an OS X command line tool that takes an RTF file as input and outputs a file with the extension .data that contains the NSData from NSCoding. I then put the .data file into my project and add a couple of lines of code that loads the text into the view. The code looks like this (this project was in Swift) :

/*
If we can load a file called "Dates.data" from the bundle and convert it to an attributed string,
install it in the dates field. The contents contain clickable links with custom URLS to select
each date.
*/
if
  let datesPath = NSBundle.mainBundle().pathForResource("Dates", ofType: "data"),
  let datesString = NSKeyedUnarchiver.unarchiveObjectWithFile(datesPath) as? NSAttributedString
{
  datesField.attributedText = datesString
}

For apps that use a lot of formatted text, I create a build rule that tells Xcode that all the .rtf files in a given folder are source and the .data files are the output. Once I do that, I simply add .rtf files to the designated directory, (or edit existing files) and the build process figures out that they are new/updated, runs the command line tool, and copies the files into the app bundle. It works beautifully.

I wrote a blog post that links to a sample (Swift) project demonstrating the technique. You can see it here:

Creating clickable URLs in a UITextField that open in your app

Swift: Display HTML data in a label or textView

Swift 5

extension UIColor {
    var hexString: String {
        let components = cgColor.components
        let r: CGFloat = components?[0] ?? 0.0
        let g: CGFloat = components?[1] ?? 0.0
        let b: CGFloat = components?[2] ?? 0.0

        let hexString = String(format: "#%02lX%02lX%02lX", lroundf(Float(r * 255)), lroundf(Float(g * 255)),
                               lroundf(Float(b * 255)))

        return hexString
    }
}
extension String {
    func htmlAttributed(family: String?, size: CGFloat, color: UIColor) -> NSAttributedString? {
        do {
            let htmlCSSString = "<style>" +
                "html *" +
                "{" +
                "font-size: \(size)pt !important;" +
                "color: #\(color.hexString) !important;" +
                "font-family: \(family ?? "Helvetica"), Helvetica !important;" +
            "}</style> \(self)"

            guard let data = htmlCSSString.data(using: String.Encoding.utf8) else {
                return nil
            }

            return try NSAttributedString(data: data,
                                          options: [.documentType: NSAttributedString.DocumentType.html,
                                                    .characterEncoding: String.Encoding.utf8.rawValue],
                                          documentAttributes: nil)
        } catch {
            print("error: ", error)
            return nil
        }
    }
}

And final you can create UILabel:

func createHtmlLabel(with html: String) -> UILabel {
    let htmlMock = """
    <b>hello</b>, <i>world</i>
    """

    let descriprionLabel = UILabel()
    descriprionLabel.attributedText = htmlMock.htmlAttributed(family: "YourFontFamily", size: 15, color: .red)

    return descriprionLabel
}

Result:

enter image description here

See tutorial:

https://medium.com/@valv0/a-swift-extension-for-string-and-html-8cfb7477a510

NSAttributedString add text alignment

Swift 4 answer:

// Define paragraph style - you got to pass it along to NSAttributedString constructor
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center

// Define attributed string attributes
let attributes = [NSAttributedStringKey.paragraphStyle: paragraphStyle]

let attributedString = NSAttributedString(string:"Test", attributes: attributes)

Create tap-able "links" in the NSAttributedString of a UILabel?

Here’s a Swift implementation that is about as minimal as possible that also includes touch feedback. Caveats:

  1. You must set fonts in your NSAttributedStrings
  2. You can only use NSAttributedStrings!
  3. You must ensure your links cannot wrap (use non breaking spaces: "\u{a0}")
  4. You cannot change the lineBreakMode or numberOfLines after setting the text
  5. You create links by adding attributes with .link keys

.

public class LinkLabel: UILabel {
    private var storage: NSTextStorage?
    private let textContainer = NSTextContainer()
    private let layoutManager = NSLayoutManager()
    private var selectedBackgroundView = UIView()

    override init(frame: CGRect) {
        super.init(frame: frame)
        textContainer.lineFragmentPadding = 0
        layoutManager.addTextContainer(textContainer)
        textContainer.layoutManager = layoutManager
        isUserInteractionEnabled = true
        selectedBackgroundView.isHidden = true
        selectedBackgroundView.backgroundColor = UIColor(white: 0, alpha: 0.3333)
        selectedBackgroundView.layer.cornerRadius = 4
        addSubview(selectedBackgroundView)
    }

    public required convenience init(coder: NSCoder) {
        self.init(frame: .zero)
    }

    public override func layoutSubviews() {
        super.layoutSubviews()
        textContainer.size = frame.size
    }

    public override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesBegan(touches, with: event)
        setLink(for: touches)
    }

    public override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesMoved(touches, with: event)
        setLink(for: touches)
    }

    private func setLink(for touches: Set<UITouch>) {
        if let pt = touches.first?.location(in: self), let (characterRange, _) = link(at: pt) {
            let glyphRange = layoutManager.glyphRange(forCharacterRange: characterRange, actualCharacterRange: nil)
            selectedBackgroundView.frame = layoutManager.boundingRect(forGlyphRange: glyphRange, in: textContainer).insetBy(dx: -3, dy: -3)
            selectedBackgroundView.isHidden = false
        } else {
            selectedBackgroundView.isHidden = true
        }
    }

    public override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesCancelled(touches, with: event)
        selectedBackgroundView.isHidden = true
    }

    public override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesEnded(touches, with: event)
        selectedBackgroundView.isHidden = true

        if let pt = touches.first?.location(in: self), let (_, url) = link(at: pt) {
            UIApplication.shared.open(url)
        }
    }

    private func link(at point: CGPoint) -> (NSRange, URL)? {
        let touchedGlyph = layoutManager.glyphIndex(for: point, in: textContainer)
        let touchedChar = layoutManager.characterIndexForGlyph(at: touchedGlyph)
        var range = NSRange()
        let attrs = attributedText!.attributes(at: touchedChar, effectiveRange: &range)
        if let urlstr = attrs[.link] as? String {
            return (range, URL(string: urlstr)!)
        } else {
            return nil
        }
    }

    public override var attributedText: NSAttributedString? {
        didSet {
            textContainer.maximumNumberOfLines = numberOfLines
            textContainer.lineBreakMode = lineBreakMode
            if let txt = attributedText {
                storage = NSTextStorage(attributedString: txt)
                storage!.addLayoutManager(layoutManager)
                layoutManager.textStorage = storage
                textContainer.size = frame.size
            }
        }
    }
}

Convert HTML to NSAttributedString in iOS

Creating an NSAttributedString from HTML must be done on the main thread!

Update: It turns out that NSAttributedString HTML rendering depends on WebKit under the hood, and must be run on the main thread or it will occasionally crash the app with a SIGTRAP.

New Relic crash log:

enter image description here

Below is an updated thread-safe Swift 2 String extension:

extension String {
    func attributedStringFromHTML(completionBlock:NSAttributedString? ->()) {
        guard let data = dataUsingEncoding(NSUTF8StringEncoding) else {
            print("Unable to decode data from html string: \(self)")
            return completionBlock(nil)
        }

        let options = [NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType,
                   NSCharacterEncodingDocumentAttribute: NSNumber(unsignedInteger:NSUTF8StringEncoding)]

        dispatch_async(dispatch_get_main_queue()) {
            if let attributedString = try? NSAttributedString(data: data, options: options, documentAttributes: nil) {
                completionBlock(attributedString)
            } else {
                print("Unable to create attributed string from html string: \(self)")
                completionBlock(nil)
            }
        }
    }
}

Usage:

let html = "<center>Here is some <b>HTML</b></center>"
html.attributedStringFromHTML { attString in
    self.bodyLabel.attributedText = attString
}

Output:

enter image description here

How to underline a UILabel in swift?

Swift 5 & 4.2 one liner:

label.attributedText = NSAttributedString(string: "Text", attributes:
    [.underlineStyle: NSUnderlineStyle.single.rawValue])

Swift 4 one liner:

label.attributedText = NSAttributedString(string: "Text", attributes:
    [.underlineStyle: NSUnderlineStyle.styleSingle.rawValue])

Swift 3 one liner:

label.attributedText = NSAttributedString(string: "Text", attributes:
      [NSUnderlineStyleAttributeName: NSUnderlineStyle.styleSingle.rawValue])

Change string color with NSAttributedString?

For Swift 5:

var attributes = [NSAttributedString.Key: AnyObject]()
attributes[.foregroundColor] = UIColor.red

let attributedString = NSAttributedString(string: "Very Bad", attributes: attributes)

label.attributedText = attributedString

For Swift 4:

var attributes = [NSAttributedStringKey: AnyObject]()
attributes[.foregroundColor] = UIColor.red

let attributedString = NSAttributedString(string: "Very Bad", attributes: attributes)

label.attributedText = attributedString

For Swift 3:

var attributes = [String: AnyObject]()
attributes[NSForegroundColorAttributeName] = UIColor.red

let attributedString = NSAttributedString(string: "Very Bad", attributes: attributes)

label.attributedText = attributedString

boundingRectWithSize for NSAttributedString returning wrong size

Ok so I spent lots of time debugging this. I found out that the maximum text height as defined by boundingRectWithSize allowed to display text by my UITextView was lower than the frame size.

In my case the frame is at most 140pt but the UITextView tolerate texts at most 131pt.

I had to figure that out manually and hardcode the "real" maximum height.

Here is my solution:

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
    NSString *proposedText = [textView.text stringByReplacingCharactersInRange:range withString:text];
    NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:proposedText];
    CGRect boundingRect;
    CGFloat maxFontSize = 100;
    CGFloat minFontSize = 30;
    CGFloat fontSize = maxFontSize + 1;
    BOOL fit;
    NSLog(@"Trying text: \"%@\"", proposedText);
    do {
        fontSize -= 1;
        //XXX Seems like trailing whitespaces count for 0. find a workaround
        [attributedText addAttribute:NSFontAttributeName value:[textView.font fontWithSize:fontSize] range:NSMakeRange(0, attributedText.length)];
        CGFloat padding = textView.textContainer.lineFragmentPadding;
        CGSize boundingSize = CGSizeMake(textView.frame.size.width - padding * 2, CGFLOAT_MAX);
        boundingRect = [attributedText boundingRectWithSize:boundingSize options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading context:nil];
        NSLog(@"bounding rect for font %f is %@; (max is %f %f). Padding: %f", fontSize, NSStringFromCGRect(boundingRect), textView.frame.size.width, 148.0, padding);
        fit =  boundingRect.size.height <= 131;
    } while (!fit && fontSize > minFontSize);
    if (fit) {
        self.textView.font = [self.textView.font fontWithSize:fontSize];
        NSLog(@"Fit!");
    } else {
        NSLog(@"No fit");
    }
    return fit;
}

How do I make an attributed string using Swift?

Details

  • Swift 5.2, Xcode 11.4 (11E146)

Solution

protocol AttributedStringComponent {
    var text: String { get }
    func getAttributes() -> [NSAttributedString.Key: Any]?
}

// MARK: String extensions

extension String: AttributedStringComponent {
    var text: String { self }
    func getAttributes() -> [NSAttributedString.Key: Any]? { return nil }
}

extension String {
    func toAttributed(with attributes: [NSAttributedString.Key: Any]?) -> NSAttributedString {
        .init(string: self, attributes: attributes)
    }
}

// MARK: NSAttributedString extensions

extension NSAttributedString: AttributedStringComponent {
    var text: String { string }

    func getAttributes() -> [Key: Any]? {
        if string.isEmpty { return nil }
        var range = NSRange(location: 0, length: string.count)
        return attributes(at: 0, effectiveRange: &range)
    }
}

extension NSAttributedString {

    convenience init?(from attributedStringComponents: [AttributedStringComponent],
                      defaultAttributes: [NSAttributedString.Key: Any],
                      joinedSeparator: String = " ") {
        switch attributedStringComponents.count {
        case 0: return nil
        default:
            var joinedString = ""
            typealias SttributedStringComponentDescriptor = ([NSAttributedString.Key: Any], NSRange)
            let sttributedStringComponents = attributedStringComponents.enumerated().flatMap { (index, component) -> [SttributedStringComponentDescriptor] in
                var components = [SttributedStringComponentDescriptor]()
                if index != 0 {
                    components.append((defaultAttributes,
                                       NSRange(location: joinedString.count, length: joinedSeparator.count)))
                    joinedString += joinedSeparator
                }
                components.append((component.getAttributes() ?? defaultAttributes,
                                   NSRange(location: joinedString.count, length: component.text.count)))
                joinedString += component.text
                return components
            }

            let attributedString = NSMutableAttributedString(string: joinedString)
            sttributedStringComponents.forEach { attributedString.addAttributes($0, range: $1) }
            self.init(attributedString: attributedString)
        }
    }
}

Usage

let defaultAttributes = [
    .font: UIFont.systemFont(ofSize: 16, weight: .regular),
    .foregroundColor: UIColor.blue
] as [NSAttributedString.Key : Any]

let marketingAttributes = [
    .font: UIFont.systemFont(ofSize: 20.0, weight: .bold),
    .foregroundColor: UIColor.black
] as [NSAttributedString.Key : Any]

let attributedStringComponents = [
    "pay for",
    NSAttributedString(string: "one",
                       attributes: marketingAttributes),
    "and get",
    "three!\n".toAttributed(with: marketingAttributes),
    "Only today!".toAttributed(with: [
        .font: UIFont.systemFont(ofSize: 16.0, weight: .bold),
        .foregroundColor: UIColor.red
    ])
] as [AttributedStringComponent]
let attributedText = NSAttributedString(from: attributedStringComponents, defaultAttributes: defaultAttributes)

Full Example

do not forget to paste the solution code here

import UIKit

class ViewController: UIViewController {

    private weak var label: UILabel!
    override func viewDidLoad() {
        super.viewDidLoad()
        let label = UILabel(frame: .init(x: 40, y: 40, width: 300, height: 80))
        label.numberOfLines = 2
        view.addSubview(label)
        self.label = label

        let defaultAttributes = [
            .font: UIFont.systemFont(ofSize: 16, weight: .regular),
            .foregroundColor: UIColor.blue
        ] as [NSAttributedString.Key : Any]

        let marketingAttributes = [
            .font: UIFont.systemFont(ofSize: 20.0, weight: .bold),
            .foregroundColor: UIColor.black
        ] as [NSAttributedString.Key : Any]

        let attributedStringComponents = [
            "pay for",
            NSAttributedString(string: "one",
                               attributes: marketingAttributes),
            "and get",
            "three!\n".toAttributed(with: marketingAttributes),
            "Only today!".toAttributed(with: [
                .font: UIFont.systemFont(ofSize: 16.0, weight: .bold),
                .foregroundColor: UIColor.red
            ])
        ] as [AttributedStringComponent]
        label.attributedText = NSAttributedString(from: attributedStringComponents, defaultAttributes: defaultAttributes)
        label.textAlignment = .center
    }
}

Result

enter image description here

How do you use NSAttributedString?

An easier solution with attributed string extension.

extension NSMutableAttributedString {

    // this function attaches color to string    
    func setColorForText(textToFind: String, withColor color: UIColor) {
        let range: NSRange = self.mutableString.range(of: textToFind, options: .caseInsensitive)
        self.addAttribute(NSAttributedStringKey.foregroundColor, value: color, range: range)
    }

}

Try this and see (Tested in Swift 3 & 4)

let label = UILabel()
label.frame = CGRect(x: 120, y: 100, width: 200, height: 30)
let first = "first"
let second = "second"
let third = "third"
let stringValue = "\(first)\(second)\(third)"  // or direct assign single string value like "firstsecondthird"

let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: stringValue)
attributedString.setColorForText(textToFind: first, withColor: UIColor.red)   // use variable for string "first"
attributedString.setColorForText(textToFind: "second", withColor: UIColor.green) // or direct string like this "second"
attributedString.setColorForText(textToFind: third, withColor: UIColor.blue)
label.font = UIFont.systemFont(ofSize: 26)
label.attributedText = attributedString
self.view.addSubview(label)

Here is expected result:

enter image description here

How to auto-remove trailing whitespace in Eclipse?

You don't need any plugin to do so. For instance, if you code JAVA, you can erase trailing whitespaces configuring save actions:

Eclipse 3.6

Preferences -> Java -> Editors -> Save Actions -> Check Perform the selected actions on save -> Check Additional actions -> Click the Configure.. button.

In the Code organizing tab, check Remove trailing whitespace

Angular and Typescript: Can't find names - Error: cannot find name

I was getting this error after merging my dev branch to my current branch. I spent sometime to fix the issue. As you can see in the below image, there is no problem in the codes at all.

enter image description here

So the only fix worked for me is that Restarting the VSCode

How to increase the gap between text and underlining in CSS

@last-child's answer is a great answer!

However, adding a border to my H2 produced an underline longer than the text.

If you're dynamically writing your CSS, or if like me you're lucky and know what the text will be, you can do the following:

  1. change the content to something the right length (ie the same

  2. text) set the font color to transparent (or rgba(0,0,0,0) )

to underline <h2>Processing</h2> (for example), change last-child's code to be:

a {
    text-decoration: none;
    position: relative;
}
a:after {
    content: 'Processing';
    color: transparent;

    width: 100%;
    position: absolute;
    left: 0;
    bottom: 1px;

    border-width: 0 0 1px;
    border-style: solid;
}

WPF Binding to parent DataContext

I dont know about XamGrid but that's what i'll do with a standard wpf DataGrid:

<DataGrid>
    <DataGrid.Columns>
        <DataGridTemplateColumn>
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding DataContext.MyProperty, RelativeSource={RelativeSource AncestorType=MyUserControl}}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
            <DataGridTemplateColumn.CellEditingTemplate>
                <DataTemplate>
                    <TextBox Text="{Binding DataContext.MyProperty, RelativeSource={RelativeSource AncestorType=MyUserControl}}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellEditingTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

Since the TextBlock and the TextBox specified in the cell templates will be part of the visual tree, you can walk up and find whatever control you need.

How to make html table vertically scrollable

Here's my solution (in Spring with Thymeleaf and jQuery):

html:

<!DOCTYPE html>
<html
    xmlns:th="http://www.thymeleaf.org"
    xmlns:tiles="http://www.thymeleaf.org">
    <body>
        <div id="objects" th:fragment="ObjectList">
            <br/>
            <div id='cap'>
                <span>Objects</span>
            </div>
            <div id="hdr">
                <div>
                    <div class="Cell">Name</div>
                        <div class="Cell">Type</div>
                </div>
            </div>
            <div id="bdy">
                <div th:each="object : ${objectlist}">
                        <div class="Cell" th:text="${object.name}">name</div>
                        <div class="Cell" th:text="${object.type}">type</div>
                </div>
            </div>
        </div>
    </body>
</html> 

css:

@CHARSET "UTF-8";
#cap span {
    display: table-caption;
    border:2px solid;
    font-size: 200%;
    padding: 3px;
}
#hdr {
    display:block;
    padding:0px;
    margin-left:0;
    border:2px solid;
}
#bdy {
    display:block;
    padding:0px;
    margin-left:0;
    border:2px solid;
}
#objects #bdy {
    height:300px;
    overflow-y: auto;
}
#hdr div div{
    margin-left:-3px;
    margin-right:-3px;
    text-align: right;
}
#hdr div:first-child {
    text-align: left;
}
#bdy div div {
    margin-left:-3px;
    margin-right:-3px;
    text-align: right;
}
#bdy div div:first-child {
    text-align: left;
}
.Cell
{
    display: table-cell;
    border: solid;
    border-width: thin;
    padding-left: 5px;
    padding-right: 5px;
}

javascript:

$(document).ready(function(){
    var divs = ['#objects'];
    divs.forEach(function(div)
    {
        if ($(div).length > 0)
        {
            var widths = [];
            var totalWidth = 0;
            $(div+' #hdr div div').each(function() {
                widths.push($(this).width())
            });
            $(div+' #bdy div div').each(function() {
                var col = $(this).index();
                if ( $(this).width() > widths[col] )
                {
                    widths[col] = $(this).width();
                }
            });
            $(div+' #hdr div div').each(function() {
                var newWidth = widths[$(this).index()]+5;
                $(this).css("width", newWidth);
                totalWidth += $(this).outerWidth();
            });
            $(div+' #bdy div div').each(function() {
                $(this).css("width", widths[$(this).index()]+5);
            });
            $(div+' #hdr').css("width", totalWidth);
            $(div+' #bdy').css("width", totalWidth+($(div+' #bdy').css('overflow-y')=='auto'?15:0));
        }
    })
});

How do I exclude Weekend days in a SQL Server query?

When dealing with day-of-week calculations, it's important to take account of the current DATEFIRST settings. This query will always correctly exclude weekend days, using @@DATEFIRST to account for any possible setting for the first day of the week.

SELECT *
FROM your_table
WHERE ((DATEPART(dw, date_created) + @@DATEFIRST) % 7) NOT IN (0, 1)

Mock functions in Go

If you change your function definition to use a variable instead:

var get_page = func(url string) string {
    ...
}

You can override it in your tests:

func TestDownloader(t *testing.T) {
    get_page = func(url string) string {
        if url != "expected" {
            t.Fatal("good message")
        }
        return "something"
    }
    downloader()
}

Careful though, your other tests might fail if they test the functionality of the function you override!

The Go authors use this pattern in the Go standard library to insert test hooks into code to make things easier to test:

Multiple aggregations of the same column using pandas GroupBy.agg()

TLDR; Pandas groupby.agg has a new, easier syntax for specifying (1) aggregations on multiple columns, and (2) multiple aggregations on a column. So, to do this for pandas >= 0.25, use

df.groupby('dummy').agg(Mean=('returns', 'mean'), Sum=('returns', 'sum'))

           Mean       Sum
dummy                    
1      0.036901  0.369012

OR

df.groupby('dummy')['returns'].agg(Mean='mean', Sum='sum')

           Mean       Sum
dummy                    
1      0.036901  0.369012

Pandas >= 0.25: Named Aggregation

Pandas has changed the behavior of GroupBy.agg in favour of a more intuitive syntax for specifying named aggregations. See the 0.25 docs section on Enhancements as well as relevant GitHub issues GH18366 and GH26512.

From the documentation,

To support column-specific aggregation with control over the output column names, pandas accepts the special syntax in GroupBy.agg(), known as “named aggregation”, where

  • The keywords are the output column names
  • The values are tuples whose first element is the column to select and the second element is the aggregation to apply to that column. Pandas provides the pandas.NamedAgg namedtuple with the fields ['column', 'aggfunc'] to make it clearer what the arguments are. As usual, the aggregation can be a callable or a string alias.

You can now pass a tuple via keyword arguments. The tuples follow the format of (<colName>, <aggFunc>).

import pandas as pd

pd.__version__                                                                                                                            
# '0.25.0.dev0+840.g989f912ee'

# Setup
df = pd.DataFrame({'kind': ['cat', 'dog', 'cat', 'dog'],
                   'height': [9.1, 6.0, 9.5, 34.0],
                   'weight': [7.9, 7.5, 9.9, 198.0]
})

df.groupby('kind').agg(
    max_height=('height', 'max'), min_weight=('weight', 'min'),)

      max_height  min_weight
kind                        
cat          9.5         7.9
dog         34.0         7.5

Alternatively, you can use pd.NamedAgg (essentially a namedtuple) which makes things more explicit.

df.groupby('kind').agg(
    max_height=pd.NamedAgg(column='height', aggfunc='max'), 
    min_weight=pd.NamedAgg(column='weight', aggfunc='min')
)

      max_height  min_weight
kind                        
cat          9.5         7.9
dog         34.0         7.5

It is even simpler for Series, just pass the aggfunc to a keyword argument.

df.groupby('kind')['height'].agg(max_height='max', min_height='min')    

      max_height  min_height
kind                        
cat          9.5         9.1
dog         34.0         6.0       

Lastly, if your column names aren't valid python identifiers, use a dictionary with unpacking:

df.groupby('kind')['height'].agg(**{'max height': 'max', ...})

Pandas < 0.25

In more recent versions of pandas leading upto 0.24, if using a dictionary for specifying column names for the aggregation output, you will get a FutureWarning:

df.groupby('dummy').agg({'returns': {'Mean': 'mean', 'Sum': 'sum'}})
# FutureWarning: using a dict with renaming is deprecated and will be removed 
# in a future version

Using a dictionary for renaming columns is deprecated in v0.20. On more recent versions of pandas, this can be specified more simply by passing a list of tuples. If specifying the functions this way, all functions for that column need to be specified as tuples of (name, function) pairs.

df.groupby("dummy").agg({'returns': [('op1', 'sum'), ('op2', 'mean')]})

        returns          
            op1       op2
dummy                    
1      0.328953  0.032895

Or,

df.groupby("dummy")['returns'].agg([('op1', 'sum'), ('op2', 'mean')])

            op1       op2
dummy                    
1      0.328953  0.032895

Google Maps API 3 - Custom marker color for default (dot) marker

I've extended vokimon's answer a bit, making it a bit more convenient for changing other properties as well.

function customIcon (opts) {
  return Object.assign({
    path: 'M 0,0 C -2,-20 -10,-22 -10,-30 A 10,10 0 1,1 10,-30 C 10,-22 2,-20 0,0 z M -2,-30 a 2,2 0 1,1 4,0 2,2 0 1,1 -4,0',
    fillColor: '#34495e',
    fillOpacity: 1,
    strokeColor: '#000',
    strokeWeight: 2,
    scale: 1,
  }, opts);
}

Usage:

marker.setIcon(customIcon({
  fillColor: '#fff',
  strokeColor: '#000'
}));

Or when defining a new marker:

const marker = new google.maps.Marker({
  position: {
    lat: ...,
    lng: ...
  },
  icon: customIcon({
    fillColor: '#2ecc71'
  }),
  map: map
});

jQuery OR Selector?

Finally I've found hack how to do it:

div:not(:not(.classA,.classB)) > span

(selects div with class classA OR classB with direct child span)

How do I use namespaces with TypeScript external modules?

The proper way to organize your code is to use separate directories in place of namespaces. Each class will be in it's own file, in it's respective namespace folder. index.ts will only re-export each file; no actual code should be in the index.ts file. Organizing your code like this makes it far easier to navigate, and is self-documenting based on directory structure.

// index.ts
import * as greeter from './greeter';
import * as somethingElse from './somethingElse';

export {greeter, somethingElse};

// greeter/index.ts
export * from './greetings.js';
...

// greeter/greetings.ts
export const helloWorld = "Hello World";

You would then use it as such:

import { greeter } from 'your-package'; //Import it like normal, be it from an NPM module or from a directory.
// You can also use the following syntax, if you prefer:
import * as package from 'your-package';

console.log(greeter.helloWorld);

jQuery serialize does not register checkboxes

This example assumes you want to post a form back via serialize and not serializeArray, and that an unchecked checkbox means false:

var form = $(formSelector);
var postData = form.serialize();

var checkBoxData = form.find('input[type=checkbox]:not(:checked)').map(function () {
    return encodeURIComponent(this.name) + '=' + false;
}).get().join('&');

if (checkBoxData) {
    postData += "&" + checkBoxData;
}

$.post(action, postData);

How to use particular CSS styles based on screen size / device

@media queries serve this purpose. Here's an example:

@media only screen and (max-width: 991px) and (min-width: 769px){
 /* CSS that should be displayed if width is equal to or less than 991px and larger 
  than 768px goes here */
}

@media only screen and (max-width: 991px){
 /* CSS that should be displayed if width is equal to or less than 991px goes here */
}

What is the best practice for creating a favicon on a web site?

There are several ways to create a favicon. The best way for you depends on various factors:

  • The time you can spend on this task. For many people, this is "as quick as possible".
  • The efforts you are willing to make. Like, drawing a 16x16 icon by hand for better results.
  • Specific constraints, like supporting a specific browser with odd specs.

First method: Use a favicon generator

If you want to get the job done well and quickly, you can use a favicon generator. This one creates the pictures and HTML code for all major desktop and mobiles browsers. Full disclosure: I'm the author of this site.

Advantages of such solution: it's quick and all compatibility considerations were already addressed for you.

Second method: Create a favicon.ico (desktop browsers only)

As you suggest, you can create a favicon.ico file which contains 16x16 and 32x32 pictures (note that Microsoft recommends 16x16, 32x32 and 48x48).

Then, declare it in your HTML code:

<link rel="shortcut icon" href="/path/to/icons/favicon.ico">

This method will work with all desktop browsers, old and new. But most mobile browsers will ignore the favicon.

About your suggestion of placing the favicon.ico file in the root and not declaring it: beware, although this technique works on most browsers, it is not 100% reliable. For example Windows Safari cannot find it (granted: this browser is somehow deprecated on Windows, but you get the point). This technique is useful when combined with PNG icons (for modern browsers).

Third method: Create a favicon.ico, a PNG icon and an Apple Touch icon (all browsers)

In your question, you do not mention the mobile browsers. Most of them will ignore the favicon.ico file. Although your site may be dedicated to desktop browsers, chances are that you don't want to ignore mobile browsers altogether.

You can achieve a good compatibility with:

  • favicon.ico, see above.
  • A 192x192 PNG icon for Android Chrome
  • A 180x180 Apple Touch icon (for iPhone 6 Plus; other device will scale it down as needed).

Declare them with

<link rel="shortcut icon" href="/path/to/icons/favicon.ico">
<link rel="icon" type="image/png" href="/path/to/icons/favicon-192x192.png" sizes="192x192">
<link rel="apple-touch-icon" sizes="180x180" href="/path/to/icons/apple-touch-icon-180x180.png">

This is not the full story, but it's good enough in most cases.

IBOutlet and IBAction

IBOutlet

  • It is a property.
  • When the nib(IB) file is loaded, it becomes part of encapsulated data which connects to an instance variable.
  • Each connection is unarchived and reestablished.

IBAction

  • Attribute indicates that the method is an action that you can connect to from your storyboard in Interface Builder.

@ - Dynamic pattern IB - Interface Builder

How to check programmatically if an application is installed or not in Android?

Somewhat cleaner solution than the accepted answer (based on this question):

public static boolean isAppInstalled(Context context, String packageName) {
    try {
        context.getPackageManager().getApplicationInfo(packageName, 0);
        return true;
    }
    catch (PackageManager.NameNotFoundException e) {
        return false;
    }
}

I chose to put it in a helper class as a static utility. Usage example:

boolean whatsappFound = AndroidUtils.isAppInstalled(context, "com.whatsapp");

This answer shows how to get the app from the Play Store if the app is missing, though care needs to be taken on devices that don't have the Play Store.

How to get domain URL and application name?

The following code might be useful for web application using JavaScript.

var newURL = window.location.protocol + "//"  + window.location.host + "" + window.location.pathname;

newURL = newURL.substring(0,newURL.indexOf(""));

PHP split alternative?

I want to clear here that preg_split(); is far away from it but explode(); can be used in similar way as split();

following is the comparison between split(); and explode(); usage

How was split() used

<?php

$date = "04/30/1973";
list($month, $day, $year) = split('[/.-]', $date);
echo $month; // foo
echo $day; // *
echo $year;

?>

URL: http://php.net/manual/en/function.split.php

How explode() can be used

<?php

$data = "04/30/1973";
list($month, $day, $year) = explode("/", $data);
echo $month; // foo
echo $day; // *
echo $year;

?>

URL: http://php.net/manual/en/function.explode.php

Here is how we can use it :)

How can I String.Format a TimeSpan object with a custom format in .NET?

Simple. Use TimeSpan.ToString with c, g or G. More information at MSDN

How to remove empty lines with or without whitespace in Python

Try list comprehension and string.strip():

>>> mystr = "L1\nL2\n\nL3\nL4\n  \n\nL5"
>>> mystr.split('\n')
['L1', 'L2', '', 'L3', 'L4', '  ', '', 'L5']
>>> [line for line in mystr.split('\n') if line.strip() != '']
['L1', 'L2', 'L3', 'L4', 'L5']

Error message "Unable to install or run the application. The application requires stdole Version 7.0.3300.0 in the GAC"

Interesting, I didn't have any references to stdole in my project, but I had a user still receiving the error. I had to add the reference, then change the setting to include. Hopefully that will work.

Difference between PCDATA and CDATA in DTD

The very main difference between PCDATA and CDATA is

PCDATA - Basically used for ELEMENTS while

CDATA - Used for Attributes of XML i.e ATTLIST

How to use subprocess popen Python

subprocess.Popen takes a list of arguments:

from subprocess import Popen, PIPE

process = Popen(['swfdump', '/tmp/filename.swf', '-d'], stdout=PIPE, stderr=PIPE)
stdout, stderr = process.communicate()

There's even a section of the documentation devoted to helping users migrate from os.popen to subprocess.

Python: Converting string into decimal number

If you are converting price (in string) to decimal price then....

from decimal import Decimal

price = "14000,45"
price_in_decimal = Decimal(price.replace(',','.'))

No need for the replace if your strings already use dots as a decimal separator

Angular exception: Can't bind to 'ngForIn' since it isn't a known native property

Since this is at least the third time I've wasted more than 5 min on this problem I figured I'd post the Q & A. I hope it helps someone else down the road... probably me!

I typed in instead of of in the ngFor expression.

Befor 2-beta.17, it should be:

<div *ngFor="#talk of talks">

As of beta.17, use the let syntax instead of #. See the UPDATE further down for more info.


Note that the ngFor syntax "desugars" into the following:

<template ngFor #talk [ngForOf]="talks">
  <div>...</div>
</template>

If we use in instead, it turns into

<template ngFor #talk [ngForIn]="talks">
  <div>...</div>
</template>

Since ngForIn isn't an attribute directive with an input property of the same name (like ngIf), Angular then tries to see if it is a (known native) property of the template element, and it isn't, hence the error.

UPDATE - as of 2-beta.17, use the let syntax instead of #. This updates to the following:

<div *ngFor="let talk of talks">

Note that the ngFor syntax "desugars" into the following:

<template ngFor let-talk [ngForOf]="talks">
  <div>...</div>
</template>

If we use in instead, it turns into

<template ngFor let-talk [ngForIn]="talks">
  <div>...</div>
</template>

Excel VBA - select multiple columns not in sequential order

Some things of top of my head.

Method 1.

Application.Union(Range("a1"), Range("b1"), Range("d1"), Range("e1"), Range("g1"), Range("h1")).EntireColumn.Select

Method 2.

Range("a1,b1,d1,e1,g1,h1").EntireColumn.Select

Method 3.

Application.Union(Columns("a"), Columns("b"), Columns("d"), Columns("e"), Columns("g"), Columns("h")).Select

How to setup virtual environment for Python in VS Code?

This is an adding to @Sam answer that though is correct is missing the fact that anytime you open a folder in visual studio code, it create a .vscode folder, but those can be multiple, created any time you eventually open a directory. The .vscode folder has JSON objects that content properties such "setting.json", in which one declare the Interpreter to use at that ".vscode" level( refer to this for more clarifications What is a 'workspace' in VS Code?).

{
   {
     "python.pythonPath": "VirtualEnPath/bin/python3.6"
   }
}

So potentially you could open VS code at another level in the virtual Env, it create another .vscode folder that assume as Python directory those of the global machine and so having such error, and has I experienced has nothing to do if the Virtual Env is activated or not.

This indeed what happened to me, I have indeed a DjangoRESTAPI_GEN folder in which I initially opened the IDE and it did recognize the Virtual Env Python path, the a few days after I opened it at the level where git is, so it did created another .vscode, that picked the global Python Interpreter, causing my lint in the Virtual Environment not been used, and the virtual env interpreter not even showed in "select python interpreter". But as wrote opening the IDE at the level where the .vscode that has the settings.json with correct path, it does.

Once you set the correct path in the setting.json and select the virtual env interpreter, then VS Code will automatically activate the VE in its terminal

enter image description here

Plotting images side by side using matplotlib

One thing that I found quite helpful to use to print all images :

_, axs = plt.subplots(n_row, n_col, figsize=(12, 12))
axs = axs.flatten()
for img, ax in zip(imgs, axs):
    ax.imshow(img)
plt.show()

PHP How to fix Notice: Undefined variable:

It looks like you don't have any records that match your query, so you'd want to return an empty array (or null or something) if the number of rows == 0.

No module named MySQLdb

Thanks to derevo but I think there's another good way for doing this:

  1. Download and install ActivePython
  2. Open Command Prompt
  3. Type pypm install mysql-python
  4. Read the notes specific to this package.

I think pypm is more powerful and reliable than easy_install.

Normalize data in pandas

In [92]: df
Out[92]:
           a         b          c         d
A  -0.488816  0.863769   4.325608 -4.721202
B -11.937097  2.993993 -12.916784 -1.086236
C  -5.569493  4.672679  -2.168464 -9.315900
D   8.892368  0.932785   4.535396  0.598124

In [93]: df_norm = (df - df.mean()) / (df.max() - df.min())

In [94]: df_norm
Out[94]:
          a         b         c         d
A  0.085789 -0.394348  0.337016 -0.109935
B -0.463830  0.164926 -0.650963  0.256714
C -0.158129  0.605652 -0.035090 -0.573389
D  0.536170 -0.376229  0.349037  0.426611

In [95]: df_norm.mean()
Out[95]:
a   -2.081668e-17
b    4.857226e-17
c    1.734723e-17
d   -1.040834e-17

In [96]: df_norm.max() - df_norm.min()
Out[96]:
a    1
b    1
c    1
d    1

How to get hostname from IP (Linux)?

Another simple way I found for using in LAN is

ssh [username@ip] uname -n

If you need to login command line will be

sshpass -p "[password]" ssh [username@ip] uname -n

How to break out of while loop in Python?

What I would do is run the loop until the ans is Q

ans=(R)
while not ans=='Q':
    print('Your score is so far '+str(myScore)+'.')
    print("Would you like to roll or quit?")
    ans=input("Roll...")
    if ans=='R':
        R=random.randint(1, 8)
        print("You rolled a "+str(R)+".")
        myScore=R+myScore

How to align center the text in html table row?

Here is an example with CSS and inline style attributes:

_x000D_
_x000D_
td _x000D_
{_x000D_
    height: 50px; _x000D_
    width: 50px;_x000D_
}_x000D_
_x000D_
#cssTable td _x000D_
{_x000D_
    text-align: center; _x000D_
    vertical-align: middle;_x000D_
}
_x000D_
<table border="1">_x000D_
    <tr>_x000D_
        <td style="text-align: center; vertical-align: middle;">Text</td>_x000D_
        <td style="text-align: center; vertical-align: middle;">Text</td>_x000D_
    </tr>_x000D_
</table>_x000D_
_x000D_
<table border="1" id="cssTable">_x000D_
    <tr>_x000D_
        <td>Text</td>_x000D_
        <td>Text</td>_x000D_
    </tr>_x000D_
</table>
_x000D_
_x000D_
_x000D_

http://jsfiddle.net/j2h3xo9k/

EDIT: The valign attribute is deprecated in HTML5 and should not be used.

Visual Studio keyboard shortcut to display IntelliSense

If you want to change whether it highlights the best fitting possibility, use:

Ctrl + Alt + Space

How to fill color in a cell in VBA?

You need to use cell.Text = "#N/A" instead of cell.Value = "#N/A". The error in the cell is actually just text stored in the cell.

Python circular importing?

For those of you who, like me, come to this issue from Django, you should know that the docs provide a solution: https://docs.djangoproject.com/en/1.10/ref/models/fields/#foreignkey

"...To refer to models defined in another application, you can explicitly specify a model with the full application label. For example, if the Manufacturer model above is defined in another application called production, you’d need to use:

class Car(models.Model):
    manufacturer = models.ForeignKey(
        'production.Manufacturer',
        on_delete=models.CASCADE,
)

This sort of reference can be useful when resolving circular import dependencies between two applications...."

SQL Server Management Studio, how to get execution time down to milliseconds

Include Client Statistics by pressing Ctrl+Alt+S. Then you will have all execution information in the statistics tab below.

Transparent image - background color

If I understand you right, you can do this:

<img src="image.png" style="background-color:red;" />

In fact, you can even apply a whole background-image to the image, resulting in two "layers" without the need for multi-background support in the browser ;)

HTML5 LocalStorage: Checking if a key exists

Quoting from the specification:

The getItem(key) method must return the current value associated with the given key. If the given key does not exist in the list associated with the object then this method must return null.

You should actually check against null.

if (localStorage.getItem("username") === null) {
  //...
}

Compare two objects with .equals() and == operator

the return type of object.equals is already boolean. there's no need to wrap it in a method with branches. so if you want to compare 2 objects simply compare them:

boolean b = objectA.equals(objectB);

b is already either true or false.

How can I sort a std::map first by value, then by key?

std::map will sort its elements by keys. It doesn't care about the values when sorting.

You can use std::vector<std::pair<K,V>> then sort it using std::sort followed by std::stable_sort:

std::vector<std::pair<K,V>> items;

//fill items

//sort by value using std::sort
std::sort(items.begin(), items.end(), value_comparer);

//sort by key using std::stable_sort
std::stable_sort(items.begin(), items.end(), key_comparer);

The first sort should use std::sort since it is nlog(n), and then use std::stable_sort which is n(log(n))^2 in the worst case.

Note that while std::sort is chosen for performance reason, std::stable_sort is needed for correct ordering, as you want the order-by-value to be preserved.


@gsf noted in the comment, you could use only std::sort if you choose a comparer which compares values first, and IF they're equal, sort the keys.

auto cmp = [](std::pair<K,V> const & a, std::pair<K,V> const & b) 
{ 
     return a.second != b.second?  a.second < b.second : a.first < b.first;
};
std::sort(items.begin(), items.end(), cmp);

That should be efficient.

But wait, there is a better approach: store std::pair<V,K> instead of std::pair<K,V> and then you don't need any comparer at all — the standard comparer for std::pair would be enough, as it compares first (which is V) first then second which is K:

std::vector<std::pair<V,K>> items;
//...
std::sort(items.begin(), items.end());

That should work great.

Volatile Vs Atomic

As Trying as indicated, volatile deals only with visibility.

Consider this snippet in a concurrent environment:

boolean isStopped = false;
    :
    :

    while (!isStopped) {
        // do some kind of work
    }

The idea here is that some thread could change the value of isStopped from false to true in order to indicate to the subsequent loop that it is time to stop looping.

Intuitively, there is no problem. Logically if another thread makes isStopped equal to true, then the loop must terminate. The reality is that the loop will likely never terminate even if another thread makes isStopped equal to true.

The reason for this is not intuitive, but consider that modern processors have multiple cores and that each core has multiple registers and multiple levels of cache memory that are not accessible to other processors. In other words, values that are cached in one processor's local memory are not visisble to threads executing on a different processor. Herein lies one of the central problems with concurrency: visibility.

The Java Memory Model makes no guarantees whatsoever about when changes that are made to a variable in one thread may become visible to other threads. In order to guarantee that updates are visisble as soon as they are made, you must synchronize.

The volatile keyword is a weak form of synchronization. While it does nothing for mutual exclusion or atomicity, it does provide a guarantee that changes made to a variable in one thread will become visible to other threads as soon as it is made. Because individual reads and writes to variables that are not 8-bytes are atomic in Java, declaring variables volatile provides an easy mechanism for providing visibility in situations where there are no other atomicity or mutual exclusion requirements.

What does the "no version information available" error from linux dynamic linker mean?

The "no version information available" means that the library version number is lower on the shared object. For example, if your major.minor.patch number is 7.15.5 on the machine where you build the binary, and the major.minor.patch number is 7.12.1 on the installation machine, ld will print the warning.

You can fix this by compiling with a library (headers and shared objects) that matches the shared object version shipped with your target OS. E.g., if you are going to install to RedHat 3.4.6-9 you don't want to compile on Debian 4.1.1-21. This is one of the reasons that most distributions ship for specific linux distro numbers.

Otherwise, you can statically link. However, you don't want to do this with something like PAM, so you want to actually install a development environment that matches your client's production environment (or at least install and link against the correct library versions.)

Advice you get to rename the .so files (padding them with version numbers,) stems from a time when shared object libraries did not use versioned symbols. So don't expect that playing with the .so.n.n.n naming scheme is going to help (much - it might help if you system has been trashed.)

You last option will be compiling with a library with a different minor version number, using a custom linking script: http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/gnu-linker/scripts.html

To do this, you'll need to write a custom script, and you'll need a custom installer that runs ld against your client's shared objects, using the custom script. This requires that your client have gcc or ld on their production system.

Mime type for WOFF fonts?

Thing that did it for me was to add this to my mime_types.rb initializer:

Rack::Mime::MIME_TYPES['.woff'] = 'font/woff'

and wipe out the cache

rake tmp:cache:clear

before restarting the server.

Source: https://github.com/sstephenson/sprockets/issues/366#issuecomment-9085509

Rails - passing parameters in link_to

First of all, link_to is a html tag helper, its second argument is the url, followed by html_options. What you would like is to pass account_id as a url parameter to the path. If you have set up named routes correctly in routes.rb, you can use path helpers.

link_to "+ Service", new_my_service_path(:account_id => acct.id)

I think the best practice is to pass model values as a param nested within :

link_to "+ Service", new_my_service_path(:my_service => { :account_id => acct.id })

# my_services_controller.rb
def new
  @my_service = MyService.new(params[:my_service])
end

And you need to control that account_id is allowed for 'mass assignment'. In rails 3 you can use powerful controls to filter valid params within the controller where it belongs. I highly recommend.

http://apidock.com/rails/ActiveModel/MassAssignmentSecurity/ClassMethods

Also note that if account_id is not freely set by the user (e.g., a user can only submit a service for the own single account_id, then it is better practice not to send it via the request, but set it within the controller by adding something like:

@my_service.account_id = current_user.account_id 

You can surely combine the two if you only allow users to create service on their own account, but allow admin to create anyone's by using roles in attr_accessible.

hope this helps

Node.js Generate html

You can use jade + express:

app.get('/', function (req, res) { res.render('index', { title : 'Home' } ) });

above you see 'index' and an object {title : 'Home'}, 'index' is your html and the object is your data that will be rendered in your html.

starting file download with JavaScript

If this is your own server application then i suggest using the following header

Content-disposition: attachment; filename=fname.ext

This will force any browser to download the file and not render it in the browser window.

no default constructor exists for class

Because you have this:

Blowfish(BlowfishAlgorithm algorithm);

It's not a default constructor. The default constructor is one which takes no parameters. i.e.

Blowfish();

How to write an XPath query to match two attributes?

Sample XML:

<X>
<Y ATTRIB1=attrib1_value ATTRIB2=attrib2_value/>
</X>

string xPath="/" + X + "/" + Y +
"[@" + ATTRIB1 + "='" + attrib1_value + "']" +
"[@" + ATTRIB2 + "='" + attrib2_value + "']"

XPath Testbed: http://www.whitebeam.org/library/guide/TechNotes/xpathtestbed.rhtm

Iterate a certain number of times without storing the iteration number anywhere

Although I agree completely with delnan's answer, it's not impossible:

loop = range(NUM_ITERATIONS+1)
while loop.pop():
    do_stuff()

Note, however, that this will not work for an arbitrary list: If the first value in the list (the last one popped) does not evaluate to False, you will get another iteration and an exception on the next pass: IndexError: pop from empty list. Also, your list (loop) will be empty after the loop.

Just for curiosity's sake. ;)

What does $@ mean in a shell script?

The usage of a pure $@ means in most cases "hurt the programmer as hard as you can", because in most cases it leads to problems with word separation and with spaces and other characters in arguments.

In (guessed) 99% of all cases, it is required to enclose it in ": "$@" is what can be used to reliably iterate over the arguments.

for a in "$@"; do something_with "$a"; done

Head and tail in one line

Under Python 3.x, you can do this nicely:

>>> head, *tail = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
>>> head
1
>>> tail
[1, 2, 3, 5, 8, 13, 21, 34, 55]

A new feature in 3.x is to use the * operator in unpacking, to mean any extra values. It is described in PEP 3132 - Extended Iterable Unpacking. This also has the advantage of working on any iterable, not just sequences.

It's also really readable.

As described in the PEP, if you want to do the equivalent under 2.x (without potentially making a temporary list), you have to do this:

it = iter(iterable)
head, tail = next(it), list(it)

As noted in the comments, this also provides an opportunity to get a default value for head rather than throwing an exception. If you want this behaviour, next() takes an optional second argument with a default value, so next(it, None) would give you None if there was no head element.

Naturally, if you are working on a list, the easiest way without the 3.x syntax is:

head, tail = seq[0], seq[1:]

Remove all files in a directory

Please see my answer here:

https://stackoverflow.com/a/24844618/2293304

It's a long and ugly, but reliable and efficient solution.

It resolves a few problems which are not addressed by the other answerers:

  • It correctly handles symbolic links, including not calling shutil.rmtree() on a symbolic link (which will pass the os.path.isdir() test if it links to a directory).
  • It handles read-only files nicely.

python save image from url

A sample code that works for me on Windows:

import requests

with open('pic1.jpg', 'wb') as handle:
        response = requests.get(pic_url, stream=True)

        if not response.ok:
            print response

        for block in response.iter_content(1024):
            if not block:
                break

            handle.write(block)

Center-align a HTML table

<table align="center"></table>

This works for me.

How do I pass a URL with multiple parameters into a URL?

I see you're having issues with the social share links. I had a similar issue at some point and found this question, but I don't see a complete answer for it. I hope my javascript resolution from below will help:

I had default sharing links that needed to be modified so that the URL that's being shared will have additional UTM parameters concatenated.

My example will be for the Facebook social share link, but it works for all the possible social sharing network links:

The URL that needed to be shared was:

https://mywebsitesite.com/blog/post-name

The default sharing link looked like:

$facebook_default = "https://www.facebook.com/sharer.php?u=https%3A%2F%2mywebsitesite.com%2Fblog%2Fpost-name%2F&t=hello"

I first DECODED it:

console.log( decodeURIComponent($facebook_default) );
=>
https://www.facebook.com/sharer.php?u=https://mywebsitesite.com/blog/post-name/&t=hello

Then I replaced the URL with the encoded new URL (with the UTM parameters concatenated):

console.log( decodeURIComponent($facebook_default).replace( window.location.href, encodeURIComponent(window.location.href+'?utm_medium=social&utm_source=facebook')) );

=>

https://www.facebook.com/sharer.php?u=https%3A%2F%mywebsitesite.com%2Fblog%2Fpost-name%2F%3Futm_medium%3Dsocial%26utm_source%3Dfacebook&t=2018

That's it!

Complete solution:

$facebook_default = $('a.facebook_default_link').attr('href');

$('a.facebook_default_link').attr( 'href', decodeURIComponent($facebook_default).replace( window.location.href, encodeURIComponent(window.location.href+'?utm_medium=social&utm_source=facebook')) );

ssl.SSLError: tlsv1 alert protocol version

Another source of this problem: I found that in Debian 9, the Python httplib2 is hardcoded to insist on TLS v1.0. So any application that uses httplib2 to connect to a server that insists on better security fails with TLSV1_ALERT_PROTOCOL_VERSION.

I fixed it by changing

context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)

to

context = ssl.SSLContext()

in /usr/lib/python3/dist-packages/httplib2/__init__.py .

Debian 10 doesn't have this problem.

HTML <sup /> tag affecting line height, how to make it consistent?

I prefer to use length on the vertical-align. This aligns the baseline of the element at the given length above the baseline of its parent.

sup {
   font-size: .83em;
   vertical-align: 0.25em;
   line-height: 0;
}

Why is "npm install" really slow?

I was having this problem and none of the solutions in SO helped. I figured it out so I am posting it here in case any one else has a similar issue.

I was trying to run npm i on an amazon instance. The problem ended up being the fact that linux only opens up a certain amount of ports, and when npm i runs, it opens like more than a thousand connects to the registry to download all the packages. So it would work but then just freeze for like 15 minutes. Then the timeout would occur and it would eventually move on to another port. So in my security group in AWS I added a rule for All TCP at 0.0.0.0/0 in outgoing only, letting npm open as many outgoing connections as it likes and that fixed it.

Cannot attach the file *.mdf as database

I think that for SQL Server Local Db you shouldn't use the Initial Catalog property. I suggest to use:

<add name="DefaultConnection" 
     connectionString="Data Source=(LocalDb)\v11.0;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\OdeToFoodDb.mdf" 
     providerName="System.Data.SqlClient" />

I think that local db doesn't support multiple database on the same mdf file so specify an initial catalog is not supported (or not well supported and I have some strange errors).

Rails: Address already in use - bind(2) (Errno::EADDRINUSE)

If the above solutions don't work on ubuntu/linux then you can try this

sudo fuser -k -n tcp port

Run it several times to kill processes on your port of choosing. port could be 3000 for example. You would have killed all the processes if you see no output after running the command

how to do bitwise exclusive or of two strings in python?

def xor_strings(s1, s2):
    max_len = max(len(s1), len(s2))
    s1 += chr(0) * (max_len - len(s1))
    s2 += chr(0) * (max_len - len(s2))
    return ''.join([chr(ord(c1) ^ ord(c2)) for c1, c2 in zip(s1, s2)])

When should I use double or single quotes in JavaScript?

It's mostly a matter of style and preference. There are some rather interesting and useful technical explorations in the other answers, so perhaps the only thing I might add is to offer a little worldly advice.

  • If you're coding in a company or team, then it's probably a good idea to follow the "house style".

  • If you're alone hacking a few side projects, then look at a few prominent leaders in the community. For example, let's say you getting into Node.js. Take a look at core modules, for example, Underscore.js or express and see what convention they use, and consider following that.

  • If both conventions are equally used, then defer to your personal preference.

  • If you don't have any personal preference, then flip a coin.

  • If you don't have a coin, then beer is on me ;)

Which programming language for cloud computing?

Of the languages you mention Java, PHP, Python, Ruby, Perl are certainly more platform independent than C/C++ (and ASP.NET).

Lots of platform-specific differences also come from what libraries are available for a given platform.

In practice however, I think you will always develop on the same or at least very similar platform (operating system flavour) as the system where your code will run, i.e. the cloud will not take source code and compile it for you before running it.

Personally I would go for Java or Python (probably also Ruby) as they have a vast number of libraries available for all kinds of tasks and are very platform independent.

Reading in a JSON File Using Swift

I'm providing another answer because none of the ones here are geared toward loading the resource from the test bundle. If you are consuming a remote service that puts out JSON and want to unit test parsing the results without hitting the actual service, you take one or more responses and put them into files in the Tests folder in your project.

func testCanReadTestJSONFile() {
    let path = NSBundle(forClass: ForecastIOAdapterTests.self).pathForResource("ForecastIOSample", ofType: "json")
    if let jsonData = NSData(contentsOfFile:path!) {
        let json = JSON(data: jsonData)
        if let currentTemperature = json["currently"]["temperature"].double {
            println("json: \(json)")
            XCTAssertGreaterThan(currentTemperature, 0)
        }
    }
}

This also uses SwiftyJSON but the core logic of getting the test bundle and loading the file is the answer to the question.

Get the difference between dates in terms of weeks, months, quarters, and years

A more "precise" calculation. That is, the number of week/month/quarter/year for a non-complete week/month/quarter/year is the fraction of calendar days in that week/month/quarter/year. For example, the number of months between 2016-02-22 and 2016-03-31 is 8/29 + 31/31 = 1.27586

explanation inline with code

#' Calculate precise number of periods between 2 dates
#' 
#' @details The number of week/month/quarter/year for a non-complete week/month/quarter/year 
#'     is the fraction of calendar days in that week/month/quarter/year. 
#'     For example, the number of months between 2016-02-22 and 2016-03-31 
#'     is 8/29 + 31/31 = 1.27586
#' 
#' @param startdate start Date of the interval
#' @param enddate end Date of the interval
#' @param period character. It must be one of 'day', 'week', 'month', 'quarter' and 'year'
#' 
#' @examples 
#' identical(numPeriods(as.Date("2016-02-15"), as.Date("2016-03-31"), "month"), 15/29 + 1)
#' identical(numPeriods(as.Date("2016-02-15"), as.Date("2016-03-31"), "quarter"), (15 + 31)/(31 + 29 + 31))
#' identical(numPeriods(as.Date("2016-02-15"), as.Date("2016-03-31"), "year"), (15 + 31)/366)
#' 
#' @return exact number of periods between
#' 
numPeriods <- function(startdate, enddate, period) {

    numdays <- as.numeric(enddate - startdate) + 1
    if (grepl("day", period, ignore.case=TRUE)) {
        return(numdays)

    } else if (grepl("week", period, ignore.case=TRUE)) {
        return(numdays / 7)
    }

    #create a sequence of dates between start and end dates
    effDaysinBins <- cut(seq(startdate, enddate, by="1 day"), period)

    #use the earliest start date of the previous bins and create a breaks of periodic dates with
    #user's period interval
    intervals <- seq(from=as.Date(min(levels(effDaysinBins)), "%Y-%m-%d"), 
        by=paste("1",period), 
        length.out=length(levels(effDaysinBins))+1)

    #create a sequence of dates between the earliest interval date and last date of the interval
    #that contains the enddate
    allDays <- seq(from=intervals[1],
        to=intervals[intervals > enddate][1] - 1,
        by="1 day")

    #bin all days in the whole period using previous breaks
    allDaysInBins <- cut(allDays, intervals)

    #calculate ratio of effective days to all days in whole period
    sum( tabulate(effDaysinBins) / tabulate(allDaysInBins) )
} #numPeriods

Please let me know if you find more boundary cases where the above solution does not work.

How to set width of a div in percent in JavaScript?

testjs2

    $(document).ready(function() { 
      $("#form1").validate({ 
        rules: { 
          name: "required", //simple rule, converted to {required:true} 
          email: { //compound rule 
          required: true, 
          email: true 
        }, 
        url: { 
          url: true 
        }, 
        comment: { 
          required: true 
        } 
        }, 
        messages: { 
          comment: "Please enter a comment." 
        } 
      }); 
    }); 

    function()
    {
    var ok=confirm('Click "OK" to go to yahoo, "CANCEL" to go to hotmail')
    if (ok)
    location="http://www.yahoo.com"
    else
    location="http://www.hotmail.com"
    }

    function changeWidth(){
    var e1 = document.getElementById("e1");
    e1.style.width = 400;
} 

  </script> 

  <style type="text/css"> 
    * { font-family: Verdana; font-size: 11px; line-height: 14px; } 
    .submit { margin-left: 125px; margin-top: 10px;} 
    .label { display: block; float: left; width: 120px; text-align: right; margin-right: 5px; } 
    .form-row { padding: 5px 0; clear: both; width: 700px; } 
    .label.error { width: 250px; display: block; float: left; color: red; padding-left: 10px; } 
    .input[type=text], textarea { width: 250px; float: left; } 
    .textarea { height: 50px; } 
  </style> 

  </head> 
  <body> 

    <form id="form1" method="post" action=""> 
      <div class="form-row"><span class="label">Name *</span><input type="text" name="name" /></div> 
      <div class="form-row"><span class="label">E-Mail *</span><input type="text" name="email" /></div> 
      <div class="form-row"><span class="label">URL </span><input type="text" name="url" /></div> 
      <div class="form-row"><span class="label">Your comment *</span><textarea name="comment" ></textarea></div> 
      <div class="form-row"><input class="submit" type="submit" value="Submit"></div> 
      <input type="button" value="change width" onclick="changeWidth()"/>
      <div id="e1" style="width:20px;height:20px; background-color:#096"></div>
    </form> 



  </body> 
</html> 

How to loop and render elements in React-native?

You would usually use map for that kind of thing.

buttonsListArr = initialArr.map(buttonInfo => (
  <Button ... key={buttonInfo[0]}>{buttonInfo[1]}</Button>
);

(key is a necessary prop whenever you do mapping in React. The key needs to be a unique identifier for the generated component)

As a side, I would use an object instead of an array. I find it looks nicer:

initialArr = [
  {
    id: 1,
    color: "blue",
    text: "text1"
  },
  {
    id: 2,
    color: "red",
    text: "text2"
  },
];

buttonsListArr = initialArr.map(buttonInfo => (
  <Button ... key={buttonInfo.id}>{buttonInfo.text}</Button>
);

Which "href" value should I use for JavaScript links, "#" or "javascript:void(0)"?

Don't lose sight of the fact that your URL may be necessary -- onclick is fired before the reference is followed, so sometimes you will need to process something clientside before navigating off the page.

AngularJS - Access to child scope

Scopes in AngularJS use prototypal inheritance, when looking up a property in a child scope the interpreter will look up the prototype chain starting from the child and continue to the parents until it finds the property, not the other way around.

Check Vojta's comments on the issue https://groups.google.com/d/msg/angular/LDNz_TQQiNE/ygYrSvdI0A0J

In a nutshell: You cannot access child scopes from a parent scope.

Your solutions:

  1. Define properties in parents and access them from children (read the link above)
  2. Use a service to share state
  3. Pass data through events. $emit sends events upwards to parents until the root scope and $broadcast dispatches events downwards. This might help you to keep things semantically correct.

How can I create tests in Android Studio?

One of the major changes it seems is that with Android Studio the test application is integrated into the application project.

I'm not sure if this helps your specific problem, but I found a guide on making tests with a Gradle project. Android Gradle user Guide

Linux command: How to 'find' only text files?

Here's a simplified version with extended explanation for beginners like me who are trying to learn how to put more than one command in one line.

If you were to write out the problem in steps, it would look like this:

// For every file in this directory
// Check the filetype
// If it's an ASCII file, then print out the filename

To achieve this, we can use three UNIX commands: find, file, and grep.

find will check every file in the directory.

file will give us the filetype. In our case, we're looking for a return of 'ASCII text'

grep will look for the keyword 'ASCII' in the output from file

So how can we string these together in a single line? There are multiple ways to do it, but I find that doing it in order of our pseudo-code makes the most sense (especially to a beginner like me).

find ./ -exec file {} ";" | grep 'ASCII'

Looks complicated, but not bad when we break it down:

find ./ = look through every file in this directory. The find command prints out the filename of any file that matches the 'expression', or whatever comes after the path, which in our case is the current directory or ./

The most important thing to understand is that everything after that first bit is going to be evaluated as either True or False. If True, the file name will get printed out. If not, then the command moves on.

-exec = this flag is an option within the find command that allows us to use the result of some other command as the search expression. It's like calling a function within a function.

file {} = the command being called inside of find. The file command returns a string that tells you the filetype of a file. Regularly, it would look like this: file mytextfile.txt. In our case, we want it to use whatever file is being looked at by the find command, so we put in the curly braces {} to act as an empty variable, or parameter. In other words, we're just asking for the system to output a string for every file in the directory.

";" = this is required by find and is the punctuation mark at the end of our -exec command. See the manual for 'find' for more explanation if you need it by running man find.

| grep 'ASCII' = | is a pipe. Pipe take the output of whatever is on the left and uses it as input to whatever is on the right. It takes the output of the find command (a string that is the filetype of a single file) and tests it to see if it contains the string 'ASCII'. If it does, it returns true.

NOW, the expression to the right of find ./ will return true when the grep command returns true. Voila.

How to convert a string or integer to binary in Ruby?

I asked a similar question. Based on @sawa's answer, the most succinct way to represent an integer in a string in binary format is to use the string formatter:

"%b" % 245
=> "11110101"

You can also choose how long the string representation to be, which might be useful if you want to compare fixed-width binary numbers:

1.upto(10).each { |n| puts "%04b" % n }
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010

Copy a file in a sane, safe and efficient way

Copy a file in a sane way:

#include <fstream>

int main()
{
    std::ifstream  src("from.ogv", std::ios::binary);
    std::ofstream  dst("to.ogv",   std::ios::binary);

    dst << src.rdbuf();
}

This is so simple and intuitive to read it is worth the extra cost. If we were doing it a lot, better to fall back on OS calls to the file system. I am sure boost has a copy file method in its filesystem class.

There is a C method for interacting with the file system:

#include <copyfile.h>

int
copyfile(const char *from, const char *to, copyfile_state_t state, copyfile_flags_t flags);

Automatic vertical scroll bar in WPF TextBlock?

You can use

ScrollViewer.HorizontalScrollBarVisibility="Visible"
ScrollViewer.VerticalScrollBarVisibility="Visible"

These are attached property of wpf. For more information

http://wpfbugs.blogspot.in/2014/02/wpf-layout-controls-scrollviewer.html

Specifying java version in maven - differences between properties and compiler plugin

Consider the alternative:

<properties>
    <javac.src.version>1.8</javac.src.version>
    <javac.target.version>1.8</javac.target.version>
</properties>

It should be the same thing of maven.compiler.source/maven.compiler.target but the above solution works for me, otherwise the second one gets the parent specification (I have a matrioska of .pom)

Use Font Awesome Icons in CSS

No need to embed content into the CSS. You can put the badge content inside the fa element, then adjust the badge css. http://jsfiddle.net/vmjwayrk/2/

<i class="fa fa-envelope fa-5x" style="position:relative;color:grey;">
  <span style="
        background-color: navy;
        border-radius: 50%;
        font-size: .25em;
        display:block;
        position:absolute;
        text-align: center;
        line-height: 2em;
        top: -.5em;
        right: -.5em;
        width: 2em;
        height: 2em;
        border:solid 4px #fff;
        box-shadow:0px 0px 1px #000;
        color: #fff;
    ">17</span>
</i>

PHP cURL custom headers

Use the following Syntax

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,"http://www.example.com/process.php");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS,$vars);  //Post Fields
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$headers = [
    'X-Apple-Tz: 0',
    'X-Apple-Store-Front: 143444,12',
    'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
    'Accept-Encoding: gzip, deflate',
    'Accept-Language: en-US,en;q=0.5',
    'Cache-Control: no-cache',
    'Content-Type: application/x-www-form-urlencoded; charset=utf-8',
    'Host: www.example.com',
    'Referer: http://www.example.com/index.php', //Your referrer address
    'User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:28.0) Gecko/20100101 Firefox/28.0',
    'X-MicrosoftAjax: Delta=true'
];

curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$server_output = curl_exec ($ch);

curl_close ($ch);

print  $server_output ;

Best way to detect when a user leaves a web page?

For What its worth, this is what I did and maybe it can help others even though the article is old.

PHP:

session_start();

$_SESSION['ipaddress'] = $_SERVER['REMOTE_ADDR'];

if(isset($_SESSION['userID'])){
    if(!strpos($_SESSION['activeID'], '-')){
        $_SESSION['activeID'] = $_SESSION['userID'].'-'.$_SESSION['activeID'];
    }
}elseif(!isset($_SESSION['activeID'])){
    $_SESSION['activeID'] = time();
}

JS

window.setInterval(function(){
            var userid = '<?php echo $_SESSION['activeID']; ?>';
            var ipaddress = '<?php echo $_SESSION['ipaddress']; ?>';
            var action = 'data';

            $.ajax({
                url:'activeUser.php',
                method:'POST',
                data:{action:action,userid:userid,ipaddress:ipaddress},
                success:function(response){
                     //alert(response);                 
                }
            });
          }, 5000);

Ajax call to activeUser.php

if(isset($_POST['action'])){
    if(isset($_POST['userid'])){
        $stamp = time();
        $activeid = $_POST['userid'];
        $ip = $_POST['ipaddress'];

        $query = "SELECT stamp FROM activeusers WHERE activeid = '".$activeid."' LIMIT 1";
        $results = RUNSIMPLEDB($query);

        if($results->num_rows > 0){
            $query = "UPDATE activeusers SET stamp = '$stamp' WHERE activeid = '".$activeid."' AND ip = '$ip' LIMIT 1";
            RUNSIMPLEDB($query);
        }else{
            $query = "INSERT INTO activeusers (activeid,stamp,ip)
                    VALUES ('".$activeid."','$stamp','$ip')";
            RUNSIMPLEDB($query);
        }
    }
}

Database:

CREATE TABLE `activeusers` (
  `id` int(11) NOT NULL,
  `activeid` varchar(20) NOT NULL,
  `stamp` int(11) NOT NULL,
  `ip` text
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

Basically every 5 seconds the js will post to a php file that will track the user and the users ip address. Active users are simply a database record that have an update to the database time stamp within 5 seconds. Old users stop updating to the database. The ip address is used just to ensure that a user is unique so 2 people on the site at the same time don't register as 1 user.

Probably not the most efficient solution but it does the job.

Is there an alternative sleep function in C to milliseconds?

Yes - older POSIX standards defined usleep(), so this is available on Linux:

int usleep(useconds_t usec);

DESCRIPTION

The usleep() function suspends execution of the calling thread for (at least) usec microseconds. The sleep may be lengthened slightly by any system activity or by the time spent processing the call or by the granularity of system timers.

usleep() takes microseconds, so you will have to multiply the input by 1000 in order to sleep in milliseconds.


usleep() has since been deprecated and subsequently removed from POSIX; for new code, nanosleep() is preferred:

#include <time.h>

int nanosleep(const struct timespec *req, struct timespec *rem);

DESCRIPTION

nanosleep() suspends the execution of the calling thread until either at least the time specified in *req has elapsed, or the delivery of a signal that triggers the invocation of a handler in the calling thread or that terminates the process.

The structure timespec is used to specify intervals of time with nanosecond precision. It is defined as follows:

struct timespec {
    time_t tv_sec;        /* seconds */
    long   tv_nsec;       /* nanoseconds */
};

An example msleep() function implemented using nanosleep(), continuing the sleep if it is interrupted by a signal:

#include <time.h>
#include <errno.h>    

/* msleep(): Sleep for the requested number of milliseconds. */
int msleep(long msec)
{
    struct timespec ts;
    int res;

    if (msec < 0)
    {
        errno = EINVAL;
        return -1;
    }

    ts.tv_sec = msec / 1000;
    ts.tv_nsec = (msec % 1000) * 1000000;

    do {
        res = nanosleep(&ts, &ts);
    } while (res && errno == EINTR);

    return res;
}

how to activate a textbox if I select an other option in drop down box

As Umesh Patil answer have comment say that there is problem. I try to edit answer and get reject. And get suggest to post new answer. This code should solve problem they have (Shashi Roy, Gaven, John Higgins).

<html> 
<head>  
<script type="text/javascript">
function CheckColors(val){
 var element=document.getElementById('othercolor');
 if(val=='others')
   element.style.display='block';
 else  
   element.style.display='none';
}

</script> 
</head>
<body>
  <select name="color" onchange='CheckColors(this.value);'> 
    <option>pick a color</option>  
    <option value="red">RED</option>
    <option value="blue">BLUE</option>
    <option value="others">others</option>
  </select>
<input type="text" name="othercolor" id="othercolor" style='display:none;'/>
</body>
</html>

Creating an IFRAME using JavaScript

You can use:

<script type="text/javascript">
    function prepareFrame() {
        var ifrm = document.createElement("iframe");
        ifrm.setAttribute("src", "http://google.com/");
        ifrm.style.width = "640px";
        ifrm.style.height = "480px";
        document.body.appendChild(ifrm);
    }
</script> 

also check basics of the iFrame element

Grouping switch statement cases together?

gcc has a so-called "case range" extension:

http://gcc.gnu.org/onlinedocs/gcc-4.2.4/gcc/Case-Ranges.html#Case-Ranges

I used to use this when I was only using gcc. Not much to say about it really -- it does sort of what you want, though only for ranges of values.

The biggest problem with this is that only gcc supports it; this may or may not be a problem for you.

(I suspect that for your example an if statement would be a more natural fit.)

How to Sort a List<T> by a property in the object

hi just to come back at the question. If you want to sort the List of this sequence "1" "10" "100" "200" "2" "20" "3" "30" "300" and get the sorted items in this form 1;2;3;10;20;30;100;200;300 you can use this:

 public class OrderingAscending : IComparer<String>
    {
        public int Compare(String x, String y)
        {
            Int32.TryParse(x, out var xtmp);
            Int32.TryParse(y, out var ytmp);

            int comparedItem = xtmp.CompareTo(ytmp);
            return comparedItem;
        }
    }

and you can use it in code behind in this form:

 IComparer<String> comparerHandle = new OrderingAscending();
 yourList.Sort(comparerHandle);

Java IOException "Too many open files"

For UNIX:

As Stephen C has suggested, changing the maximum file descriptor value to a higher value avoids this problem.

Try looking at your present file descriptor capacity:

   $ ulimit -n

Then change the limit according to your requirements.

   $ ulimit -n <value>

Note that this just changes the limits in the current shell and any child / descendant process. To make the change "stick" you need to put it into the relevant shell script or initialization file.

How to Select Min and Max date values in Linq Query

If you are looking for the oldest date (minimum value), you'd sort and then take the first item returned. Sorry for the C#:

var min = myData.OrderBy( cv => cv.Date1 ).First();

The above will return the entire object. If you just want the date returned:

var min = myData.Min( cv => cv.Date1 );

Regarding which direction to go, re: Linq to Sql vs Linq to Entities, there really isn't much choice these days. Linq to Sql is no longer being developed; Linq to Entities (Entity Framework) is the recommended path by Microsoft these days.

From Microsoft Entity Framework 4 in Action (MEAP release) by Manning Press:

What about the future of LINQ to SQL?

It's not a secret that LINQ to SQL is included in the Framework 4.0 for compatibility reasons. Microsoft has clearly stated that Entity Framework is the recommended technology for data access. In the future it will be strongly improved and tightly integrated with other technologies while LINQ to SQL will only be maintained and little evolved.

Create an instance of a class from a string

To create an instance of a class from another project in the solution, you can get the assembly indicated by the name of any class (for example BaseEntity) and create a new instance:

  var newClass = System.Reflection.Assembly.GetAssembly(typeof(BaseEntity)).CreateInstance("MyProject.Entities.User");

Array[n] vs Array[10] - Initializing array with variable vs real number

In C++, variable length arrays are not legal. G++ allows this as an "extension" (because C allows it), so in G++ (without being -pedantic about following the C++ standard), you can do:

int n = 10;
double a[n]; // Legal in g++ (with extensions), illegal in proper C++

If you want a "variable length array" (better called a "dynamically sized array" in C++, since proper variable length arrays aren't allowed), you either have to dynamically allocate memory yourself:

int n = 10;
double* a = new double[n]; // Don't forget to delete [] a; when you're done!

Or, better yet, use a standard container:

int n = 10;
std::vector<double> a(n); // Don't forget to #include <vector>

If you still want a proper array, you can use a constant, not a variable, when creating it:

const int n = 10;
double a[n]; // now valid, since n isn't a variable (it's a compile time constant)

Similarly, if you want to get the size from a function in C++11, you can use a constexpr:

constexpr int n()
{
    return 10;
}

double a[n()]; // n() is a compile time constant expression

"Strict Standards: Only variables should be passed by reference" error

array_shift the only parameter is an array passed by reference. The return value of explode(".", $value) does not have any reference. Hence the error.

You should store the return value to a variable first.

    $arr = explode(".", $value);
    $extension = strtolower(array_pop($arr));   
    $fileName = array_shift($arr);

From PHP.net

The following things can be passed by reference:

- Variables, i.e. foo($a)
- New statements, i.e. foo(new foobar())
- [References returned from functions][2]

No other expressions should be passed by reference, as the result is undefined. For example, the following examples of passing by reference are invalid:

Show ProgressDialog Android

While creating the object for the progressbar check the following.

This fails:

dialog = new ProgressDialog(getApplicationContext());

While adding the activities context works..

dialog = new ProgressDialog(MainActivity.this);

What does it mean to write to stdout in C?

stdout stands for standard output stream and it is a stream which is available to your program by the operating system itself. It is already available to your program from the beginning together with stdin and stderr.

What they point to (or from) can be anything, actually the stream just provides your program an object that can be used as an interface to send or retrieve data. By default it is usually the terminal but it can be redirected wherever you want: a file, to a pipe goint to another process and so on.

Force IE compatibility mode off using tags

The meta tag solution wasn't working for us but setting it in the response header did:

header('X-UA-Compatible: IE=edge,chrome=1');

Python Function to test ping

Try this

def ping(server='example.com', count=1, wait_sec=1):
    """

    :rtype: dict or None
    """
    cmd = "ping -c {} -W {} {}".format(count, wait_sec, server).split(' ')
    try:
        output = subprocess.check_output(cmd).decode().strip()
        lines = output.split("\n")
        total = lines[-2].split(',')[3].split()[1]
        loss = lines[-2].split(',')[2].split()[0]
        timing = lines[-1].split()[3].split('/')
        return {
            'type': 'rtt',
            'min': timing[0],
            'avg': timing[1],
            'max': timing[2],
            'mdev': timing[3],
            'total': total,
            'loss': loss,
        }
    except Exception as e:
        print(e)
        return None

Smooth scroll without the use of jQuery

Modern browsers has support for CSS "scroll-behavior: smooth" property. So, we even don't need any Javascript at all for this. Just add this to the body element, and use usual anchors and links. scroll-behavior MDN docs

Converting java.util.Properties to HashMap<String,String>

The problem is that Properties implements Map<Object, Object>, whereas the HashMap constructor expects a Map<? extends String, ? extends String>.

This answer explains this (quite counter-intuitive) decision. In short: before Java 5, Properties implemented Map (as there were no generics back then). This meant that you could put any Object in a Properties object. This is still in the documenation:

Because Properties inherits from Hashtable, the put and putAll methods can be applied to a Properties object. Their use is strongly discouraged as they allow the caller to insert entries whose keys or values are not Strings. The setProperty method should be used instead.

To maintain compatibility with this, the designers had no other choice but to make it inherit Map<Object, Object> in Java 5. It's an unfortunate result of the strive for full backwards compatibility which makes new code unnecessarily convoluted.

If you only ever use string properties in your Properties object, you should be able to get away with an unchecked cast in your constructor:

Map<String, String> map = new HashMap<String, String>( (Map<String, String>) properties);

or without any copies:

Map<String, String> map = (Map<String, String>) properties;

How do you sort a dictionary by value?

Suppose we have a dictionary as

   Dictionary<int, int> dict = new Dictionary<int, int>();
   dict.Add(21,1041);
   dict.Add(213, 1021);
   dict.Add(45, 1081);
   dict.Add(54, 1091);
   dict.Add(3425, 1061);
   sict.Add(768, 1011);

1) you can use temporary dictionary to store values as :

        Dictionary<int, int> dctTemp = new Dictionary<int, int>();

        foreach (KeyValuePair<int, int> pair in dict.OrderBy(key => key.Value))
        {
            dctTemp .Add(pair.Key, pair.Value);
        }

How to set web.config file to show full error message

not sure if it'll work in your scenario, but try adding the following to your web.config under <system.web>:

  <system.web>
    <customErrors mode="Off" />
  ...
  </system.web>

works in my instance.

also see:

CustomErrors mode="Off"

Removing index column in pandas when reading a csv

One thing that i do is df=df.reset_index() then df=df.drop(['index'],axis=1)

mysql-python install error: Cannot open include file 'config-win.h'

For mysql8 and python 3.7 on windows, I find previous solutions seems not work for me.

Here is what worked for me:

pip install wheel

pip install mysqlclient-1.4.2-cp37-cp37m-win_amd64.whl

python -m pip install mysql-connector-python

python -m pip install SQLAlchemy

Reference: https://mysql.wisborg.dk/2019/03/03/using-sqlalchemy-with-mysql-8/

Passing multiple values to a single PowerShell script parameter

I call a scheduled script who must connect to a list of Server this way:

Powershell.exe -File "YourScriptPath" "Par1,Par2,Par3"

Then inside the script:

param($list_of_servers)
...
Connect-Viserver $list_of_servers.split(",")

The split operator returns an array of string

TLS 1.2 in .NET Framework 4.0

According to this, you will need .NET 4.5 installed. For more details, visit the webpage. The gist of it is that after you have .NET 4.5 installed, your 4.0 apps will use the 4.5 System.dll. You can enable TLS 1.2 in two ways:

  • At the beginning of the application, add this code: ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
  • Set the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319: SchUseStrongCrypto to DWORD 1

Visual Studio window which shows list of methods

I have been using USysWare DPack since forever. It is very small and not intrusive so if all you want is a quick shortcut window showing list of methods of the current file you are using, it provides just that. Good thing is that the author is still active after more than 10 years just to keep providing the same features into latest VS release.

https://marketplace.visualstudio.com/items?itemName=SergeyM.DPack-16348

After installation, just use Alt + M to bring up the method list window. I prefer to show all members instead, but it's up to you.

Reading/parsing Excel (xls) files with Python

You might also consider running the (non-python) program xls2csv. Feed it an xls file, and you should get back a csv.

How can I color Python logging output?

I have two submissions to add, one of which colorizes just the message (ColoredFormatter), and one of which colorizes the entire line (ColorizingStreamHandler). These also include more ANSI color codes than previous solutions.

Some content has been sourced (with modification) from: The post above, and http://plumberjack.blogspot.com/2010/12/colorizing-logging-output-in-terminals.html.

Colorizes the message only:

class ColoredFormatter(logging.Formatter):
    """Special custom formatter for colorizing log messages!"""

    BLACK = '\033[0;30m'
    RED = '\033[0;31m'
    GREEN = '\033[0;32m'
    BROWN = '\033[0;33m'
    BLUE = '\033[0;34m'
    PURPLE = '\033[0;35m'
    CYAN = '\033[0;36m'
    GREY = '\033[0;37m'

    DARK_GREY = '\033[1;30m'
    LIGHT_RED = '\033[1;31m'
    LIGHT_GREEN = '\033[1;32m'
    YELLOW = '\033[1;33m'
    LIGHT_BLUE = '\033[1;34m'
    LIGHT_PURPLE = '\033[1;35m'
    LIGHT_CYAN = '\033[1;36m'
    WHITE = '\033[1;37m'

    RESET = "\033[0m"

    def __init__(self, *args, **kwargs):
        self._colors = {logging.DEBUG: self.DARK_GREY,
                        logging.INFO: self.RESET,
                        logging.WARNING: self.BROWN,
                        logging.ERROR: self.RED,
                        logging.CRITICAL: self.LIGHT_RED}
        super(ColoredFormatter, self).__init__(*args, **kwargs)

    def format(self, record):
        """Applies the color formats"""
        record.msg = self._colors[record.levelno] + record.msg + self.RESET
        return logging.Formatter.format(self, record)

    def setLevelColor(self, logging_level, escaped_ansi_code):
        self._colors[logging_level] = escaped_ansi_code

Colorizes the whole line:

class ColorizingStreamHandler(logging.StreamHandler):

    BLACK = '\033[0;30m'
    RED = '\033[0;31m'
    GREEN = '\033[0;32m'
    BROWN = '\033[0;33m'
    BLUE = '\033[0;34m'
    PURPLE = '\033[0;35m'
    CYAN = '\033[0;36m'
    GREY = '\033[0;37m'

    DARK_GREY = '\033[1;30m'
    LIGHT_RED = '\033[1;31m'
    LIGHT_GREEN = '\033[1;32m'
    YELLOW = '\033[1;33m'
    LIGHT_BLUE = '\033[1;34m'
    LIGHT_PURPLE = '\033[1;35m'
    LIGHT_CYAN = '\033[1;36m'
    WHITE = '\033[1;37m'

    RESET = "\033[0m"

    def __init__(self, *args, **kwargs):
        self._colors = {logging.DEBUG: self.DARK_GREY,
                        logging.INFO: self.RESET,
                        logging.WARNING: self.BROWN,
                        logging.ERROR: self.RED,
                        logging.CRITICAL: self.LIGHT_RED}
        super(ColorizingStreamHandler, self).__init__(*args, **kwargs)

    @property
    def is_tty(self):
        isatty = getattr(self.stream, 'isatty', None)
        return isatty and isatty()

    def emit(self, record):
        try:
            message = self.format(record)
            stream = self.stream
            if not self.is_tty:
                stream.write(message)
            else:
                message = self._colors[record.levelno] + message + self.RESET
                stream.write(message)
            stream.write(getattr(self, 'terminator', '\n'))
            self.flush()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)

    def setLevelColor(self, logging_level, escaped_ansi_code):
        self._colors[logging_level] = escaped_ansi_code

SQL: How do I SELECT only the rows with a unique value on certain column?

Sorry you're not using PostgreSQL...

SELECT DISTINCT ON contract, activity * FROM thetable ORDER BY contract, activity

http://www.postgresql.org/docs/8.3/static/sql-select.html#SQL-DISTINCT

Oh wait. You only want values with exactly one...

SELECT contract, activity, count() FROM thetable GROUP BY contract, activity HAVING count() = 1

How to handle a lost KeyStore password in Android?

In Ionic I was able to find it here: /app/platforms/android/app/build/intermediates/signing_config/release/out/signing-config.json

Maybe this will help someone. cheers.

How can I install Visual Studio Code extensions offline?

I wanted to throw a PowerShell download option on the pile in case anyone else comes across this. I have several offline scenarios and I run this in a loop to download and update all of the extensions I use offline.

$page = Invoke-WebRequest -Uri 'https://marketplace.visualstudio.com/items?itemName=ms-vscode.PowerShell'

$details = ( $page.Scripts | ? {$_.class -eq 'vss-extension'}).innerHTML | Convertfrom-Json

$extensionName = $details.extensionName 
$publisher     = $details.publisher.publisherName
$version       = $details.versions.version

Invoke-WebRequest -uri "$($details.versions.fallbackAssetUri)/Microsoft.VisualStudio.Services.VSIXPackage" `
                  -OutFile "C:\Scripts\extensions\$publisher.$extensionName.$version.VSIX"

Where can I view Tomcat log files in Eclipse?

Looks like the logs are scattered? I found access logs under <ProjectLocation>\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\logs

NodeJS - What does "socket hang up" actually mean?

Another case worth mentioning (for Linux and OS X) is that if you use a library like https for performing the requests, or if you pass https://... as a URL of the locally served instance, you will be using port 443 which is a reserved private port and you might be ending up in Socket hang up or ECONNREFUSED errors.

Instead, use port 3000, f.e., and do an http request.

ImportError: No module named 'google'

I figured out the solution:

  • I had to delete my anaconda and python installations
  • Re-install Anaconda only
  • Open Anaconda prompt and point it to Anaconda/Scripts
  • Run pip install google
  • Run the sample code now from Spyder.

No more errors.

Add a reference column migration in Rails 4

Rails 4.x

When you already have users and uploads tables and wish to add a new relationship between them.

All you need to do is: just generate a migration using the following command:

rails g migration AddUserToUploads user:references

Which will create a migration file as:

class AddUserToUploads < ActiveRecord::Migration
  def change
    add_reference :uploads, :user, index: true
  end
end

Then, run the migration using rake db:migrate. This migration will take care of adding a new column named user_id to uploads table (referencing id column in users table), PLUS it will also add an index on the new column.

UPDATE [For Rails 4.2]

Rails can’t be trusted to maintain referential integrity; relational databases come to our rescue here. What that means is that we can add foreign key constraints at the database level itself and ensure that database would reject any operation that violates this set referential integrity. As @infoget commented, Rails 4.2 ships with native support for foreign keys(referential integrity). It's not required but you might want to add foreign key(as it's very useful) to the reference that we created above.

To add foreign key to an existing reference, create a new migration to add a foreign key:

class AddForeignKeyToUploads < ActiveRecord::Migration
  def change
    add_foreign_key :uploads, :users
  end
end

To create a completely brand new reference with a foreign key(in Rails 4.2), generate a migration using the following command:

rails g migration AddUserToUploads user:references

which will create a migration file as:

class AddUserToUploads < ActiveRecord::Migration
  def change
    add_reference :uploads, :user, index: true
    add_foreign_key :uploads, :users
  end
end

This will add a new foreign key to the user_id column of the uploads table. The key references the id column in users table.

NOTE: This is in addition to adding a reference so you still need to create a reference first then foreign key (you can choose to create a foreign key in the same migration or a separate migration file). Active Record only supports single column foreign keys and currently only mysql, mysql2 and PostgreSQL adapters are supported. Don't try this with other adapters like sqlite3, etc. Refer to Rails Guides: Foreign Keys for your reference.

file_put_contents - failed to open stream: Permission denied

Furthermore, as said in file_put_contents man page in php.net, beware of naming issues.

file_put_contents($dir."/file.txt", "hello");

may not work (even though it is correct on syntax), but

file_put_contents("$dir/file.txt", "hello");

works. I experienced this on different php installed servers.

Binding to static property

In .NET 4.5 it's possible to bind to static properties, read more

You can use static properties as the source of a data binding. The data binding engine recognizes when the property's value changes if a static event is raised. For example, if the class SomeClass defines a static property called MyProperty, SomeClass can define a static event that is raised when the value of MyProperty changes. The static event can use either of the following signatures:

public static event EventHandler MyPropertyChanged; 
public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged; 

Note that in the first case, the class exposes a static event named PropertyNameChanged that passes EventArgs to the event handler. In the second case, the class exposes a static event named StaticPropertyChanged that passes PropertyChangedEventArgs to the event handler. A class that implements the static property can choose to raise property-change notifications using either method.

How to navigate a few folders up?

C#

string upTwoDir = Path.GetFullPath(Path.Combine(System.AppContext.BaseDirectory, @"..\..\"));

HTML 5 video or audio playlist

To add to the current answers, here is a playlist of videos which works with separate subtitle files. At the end of the playlist, it will go to endPage

<video id="video" controls autoplay preload="metadata">
   <source src="vid1.mp4" type="mp4">
   <track id="subs" label="English" kind="subtitles" srclang="en" src="sub1.vtt" default>
</video>

<script type="text/javascript">
var endPage = "duckduckgo.com";
var playlist = [
    { 
        'file': 'vid2.mp4',
        'subtitle': 'sub2.vtt'
    },{
        'file': 'vid3.mp4',
        'subtitle': 'sub3.vtt'
    }
]
var i = 0;
var videoPlayer = document.getElementById('video');
var subtitles = document.getElementById('subs');
videoPlayer.onended = function(){
    if(i < playlist.length){
        videoPlayer.src = playlist[i].file;
        subtitles.src = playlist[i].subtitle;
        i++;
    } else {
        console.log("We are leaving")
        document.location.href = endPage;
    }
}
</script>

TypeError: unsupported operand type(s) for -: 'list' and 'list'

You can't subtract a list from a list.

>>> [3, 7] - [1, 2]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for -: 'list' and 'list'

Simple way to do it is using numpy:

>>> import numpy as np
>>> np.array([3, 7]) - np.array([1, 2])
array([2, 5])

You can also use list comprehension, but it will require changing code in the function:

>>> [a - b for a, b in zip([3, 7], [1, 2])]
[2, 5]

>>> import numpy as np
>>>
>>> def Naive_Gauss(Array,b):
...     n = len(Array)
...     for column in xrange(n-1):
...         for row in xrange(column+1, n):
...             xmult = Array[row][column] / Array[column][column]
...             Array[row][column] = xmult
...             #print Array[row][col]
...             for col in xrange(0, n):
...                 Array[row][col] = Array[row][col] - xmult*Array[column][col]
...             b[row] = b[row]-xmult*b[column]
...     print Array
...     print b
...     return Array, b  # <--- Without this, the function will return `None`.
...
>>> print Naive_Gauss(np.array([[2,3],[4,5]]),
...                   np.array([[6],[7]]))
[[ 2  3]
 [-2 -1]]
[[ 6]
 [-5]]
(array([[ 2,  3],
       [-2, -1]]), array([[ 6],
       [-5]]))

What is the proper way to test if a parameter is empty in a batch file?

I created this small batch script based on the answers here, as there are many valid ones. Feel free to add to this so long as you follow the same format:

REM Parameter-testing

Setlocal EnableDelayedExpansion EnableExtensions

IF NOT "%~1"=="" (echo Percent Tilde 1 failed with quotes) ELSE (echo SUCCESS)
IF NOT [%~1]==[] (echo Percent Tilde 1 failed with brackets) ELSE (echo SUCCESS)
IF NOT  "%1"=="" (echo Quotes one failed) ELSE (echo SUCCESS)
IF NOT [%1]==[] (echo Brackets one failed) ELSE (echo SUCCESS)
IF NOT "%1."=="." (echo Appended dot quotes one failed) ELSE (echo SUCCESS)
IF NOT [%1.]==[.] (echo Appended dot brackets one failed) ELSE (echo SUCCESS)

pause

How to remove gaps between subplots in matplotlib?

Have you tried plt.tight_layout()?

with plt.tight_layout() enter image description here without it: enter image description here

Or: something like this (use add_axes)

left=[0.1,0.3,0.5,0.7]
width=[0.2,0.2, 0.2, 0.2]
rectLS=[]
for x in left:
   for y in left:
       rectLS.append([x, y, 0.2, 0.2])
axLS=[]
fig=plt.figure()
axLS.append(fig.add_axes(rectLS[0]))
for i in [1,2,3]:
     axLS.append(fig.add_axes(rectLS[i],sharey=axLS[-1]))    
axLS.append(fig.add_axes(rectLS[4]))
for i in [1,2,3]:
     axLS.append(fig.add_axes(rectLS[i+4],sharex=axLS[i],sharey=axLS[-1]))
axLS.append(fig.add_axes(rectLS[8]))
for i in [5,6,7]:
     axLS.append(fig.add_axes(rectLS[i+4],sharex=axLS[i],sharey=axLS[-1]))     
axLS.append(fig.add_axes(rectLS[12]))
for i in [9,10,11]:
     axLS.append(fig.add_axes(rectLS[i+4],sharex=axLS[i],sharey=axLS[-1]))

If you don't need to share axes, then simply axLS=map(fig.add_axes, rectLS) enter image description here

How can I list all cookies for the current page with Javascript?

No there isn't. You can only read information associated with the current domain.

Angular bootstrap datepicker date format does not format ng-model value

Finally I got work around to the above problem. angular-strap has exactly the same feature that I am expecting. Just by applying date-format="MM/dd/yyyy" date-type="string" I got my expected behavior of updating ng-model in given format.

<div class="bs-example" style="padding-bottom: 24px;" append-source>
    <form name="datepickerForm" class="form-inline" role="form">
      <!-- Basic example -->
      <div class="form-group" ng-class="{'has-error': datepickerForm.date.$invalid}">
        <label class="control-label"><i class="fa fa-calendar"></i> Date <small>(as date)</small></label>
        <input type="text"  autoclose="true"  class="form-control" ng-model="selectedDate" name="date" date-format="MM/dd/yyyy" date-type="string" bs-datepicker>
      </div>
      <hr>
      {{selectedDate}}
     </form>
</div>

here is working plunk link

programmatically add column & rows to WPF Datagrid

try this , it works 100 % : add columns and rows programatically : you need to create item class at first :

public class Item
        {
            public int Num { get; set; }
            public string Start { get; set; }
            public string Finich { get; set; }
        }

        private void generate_columns()
        {
            DataGridTextColumn c1 = new DataGridTextColumn();
            c1.Header = "Num";
            c1.Binding = new Binding("Num");
            c1.Width = 110;
            dataGrid1.Columns.Add(c1);
            DataGridTextColumn c2 = new DataGridTextColumn();
            c2.Header = "Start";
            c2.Width = 110;
            c2.Binding = new Binding("Start");
            dataGrid1.Columns.Add(c2);
            DataGridTextColumn c3 = new DataGridTextColumn();
            c3.Header = "Finich";
            c3.Width = 110;
            c3.Binding = new Binding("Finich");
            dataGrid1.Columns.Add(c3);

            dataGrid1.Items.Add(new Item() { Num = 1, Start = "2012, 8, 15", Finich = "2012, 9, 15" });
            dataGrid1.Items.Add(new Item() { Num = 2, Start = "2012, 12, 15", Finich = "2013, 2, 1" });
            dataGrid1.Items.Add(new Item() { Num = 3, Start = "2012, 8, 1", Finich = "2012, 11, 15" });

        }

Entity Framework vs LINQ to SQL

If your database is straightforward and simple, LINQ to SQL will do. If you need logical/abstracted entities on top of your tables, then go for Entity Framework.

How to remove border from specific PrimeFaces p:panelGrid?

Please try this too

.ui-panelgrid tr, .ui-panelgrid td {
border:0 !important;
}

How to make this Header/Content/Footer layout using CSS?

Try This

<!DOCTYPE html>

<html>

<head>

<title>Sticky Header and Footer</title>

<style type="text/css">

/* Reset body padding and margins */

body {
    margin:0;

    padding:0;
}

/* Make Header Sticky */

#header_container {

    background:#eee;

    border:1px solid #666;

    height:60px;

    left:0;

    position:fixed;

    width:100%;

    top:0;
}

#header {

    line-height:60px;

    margin:0 auto;

    width:940px;

    text-align:center;
}

/* CSS for the content of page. I am giving top and bottom padding of 80px to make sure the header and footer do not overlap the content.*/

#container {

    margin:0 auto;

    overflow:auto;

    padding:80px 0;

    width:940px;

}

#content {

}

/* Make Footer Sticky */

#footer_container {

    background:#eee;

    border:1px solid #666;

    bottom:0;

    height:60px;

    left:0;

    position:fixed;

    width:100%;
}

#footer {

    line-height:60px;

    margin:0 auto;

    width:940px;

    text-align:center;

}

</style>

</head>

<body>

<!-- BEGIN: Sticky Header -->
<div id="header_container">

    <div id="header">
        Header Content
    </div>

</div>
<!-- END: Sticky Header -->

<!-- BEGIN: Page Content -->
<div id="container">

    <div id="content">

            content
        <br /><br />
            blah blah blah..
        ...
    </div>

</div>
<!-- END: Page Content -->

<!-- BEGIN: Sticky Footer -->
<div id="footer_container">

    <div id="footer">

        Footer Content

    </div>

</div>

<!-- END: Sticky Footer -->

</body>

</html>

How to delete shared preferences data from App in Android

Editor editor = getSharedPreferences("clear_cache", Context.MODE_PRIVATE).edit();
editor.clear();
editor.commit();

Strange PostgreSQL "value too long for type character varying(500)"

We had this same issue. We solved it adding 'length' to entity attribute definition:

@Column(columnDefinition="text", length=10485760)
private String configFileXml = ""; 

Fatal error: "No Target Architecture" in Visual Studio

Another reason for the error (amongst many others that cropped up when changing the target build of a Win32 project to X64) was not having the C++ 64 bit compilers installed as noted at the top of this page.
Further to philipvr's comment on child headers, (in my case) an explicit include of winnt.h being unnecessary when windows.h was being used.

How to create custom view programmatically in swift having controls text field, button etc

let viewDemo = UIView()
viewDemo.frame = CGRect(x: 50, y: 50, width: 50, height: 50)
self.view.addSubview(viewDemo)

Linux / Bash, using ps -o to get process by specific name?

Sorry, much late to the party, but I'll add here that if you wanted to capture processes with names identical to your search string, you could do

pgrep -x PROCESS_NAME

-x          Require an exact match of the process name, or argument list if -f is given.
             The default is to match any substring.

This is extremely useful if your original process created child processes (possibly zombie when you query) which prefix the original process' name in their own name and you are trying to exclude them from your results. There are many UNIX daemons which do this. My go-to example is ninja-dev-sync.

Run cmd commands through Java

public class Demo { public static void main(String args[]) throws IOException {

    Process process = Runtime.getRuntime().exec("/Users/******/Library/Android/sdk/platform-tools/adb" + " shell dumpsys battery ");
    BufferedReader in = new BufferedReader(new InputStreamReader(process.getInputStream()));
    String line = null;
    while (true) {
        line = in.readLine();
        if (line == null) { break; }
        System.out.println(line);
    }
}

}

Split string into strings by length?

Here are two generic approaches. Probably worth adding to your own lib of reusables. First one requires the item to be sliceable and second one works with any iterables (but requires their constructor to accept iterable).

def split_bylen(item, maxlen):
    '''
    Requires item to be sliceable (with __getitem__ defined)
    '''
    return [item[ind:ind+maxlen] for ind in range(0, len(item), maxlen)]
    #You could also replace outer [ ] brackets with ( ) to use as generator.

def split_bylen_any(item, maxlen, constructor=None):
    '''
    Works with any iterables.
    Requires item's constructor to accept iterable or alternatively 
    constructor argument could be provided (otherwise use item's class)
    '''
    if constructor is None: constructor = item.__class__
    return [constructor(part) for part in zip(* ([iter(item)] * maxlen))]
    #OR: return map(constructor, zip(* ([iter(item)] * maxlen)))
    #    which would be faster if you need an iterable, not list

So, in topicstarter's case, the usage is:

string = 'Baboons love bananas'
parts = 5
splitlen = -(-len(string) // parts) # is alternative to math.ceil(len/parts)

first_method = split_bylen(string, splitlen)
#Result :['Babo', 'ons ', 'love', ' ban', 'anas']

second_method = split_bylen_any(string, splitlen, constructor=''.join)
#Result :['Babo', 'ons ', 'love', ' ban', 'anas']

PostgreSQL wildcard LIKE for any of a list of words

You can use Postgres' SIMILAR TO operator which supports alternations, i.e.

select * from table where lower(value) similar to '%(foo|bar|baz)%';

How to group subarrays by a column value?

In a more functional programming style, you could use array_reduce

$groupedById = array_reduce($data, function (array $accumulator, array $element) {
  $accumulator[$element['id']][] = $element;

  return $accumulator;
}, []);

Does VBA have Dictionary Structure?

VBA does not have an internal implementation of a dictionary, but from VBA you can still use the dictionary object from MS Scripting Runtime Library.

Dim d
Set d = CreateObject("Scripting.Dictionary")
d.Add "a", "aaa"
d.Add "b", "bbb"
d.Add "c", "ccc"

If d.Exists("c") Then
    MsgBox d("c")
End If

removing bold styling from part of a header

Yes you can add text inside <span> and override css. jsfiddle

html:

<h1>**This text should be bold**, <span>but this text should not</span><h1>

css:

span{
   font-weight: normal;
}

Convert list of ASCII codes to string (byte array) in Python

struct.pack('B' * len(integers), *integers)

*sequence means "unpack sequence" - or rather, "when calling f(..., *args ,...), let args = sequence".

Formula px to dp, dp to px android

variation on ct_robs answer above, if you are using integers, that not only avoids divide by 0 it also produces a usable result on small devices:

in integer calculations involving division for greatest precision multiply first before dividing to reduce truncation effects.

px = dp * dpi / 160
dp = px * 160 / dpi

5 * 120 = 600 / 160 = 3

instead of

5 * (120 / 160 = 0) = 0

if you want rounded result do this

px = (10 * dp * dpi / 160 + 5) / 10
dp = (10 * px * 160 / dpi + 5) / 10

10 * 5 * 120 = 6000 / 160 = 37 + 5 = 42 / 10 = 4

Creating a URL in the controller .NET MVC

I had the same issue, and it appears Gidon's answer has one tiny flaw: it generates a relative URL, which cannot be sent by mail.

My solution looks like this:

string link = HttpContext.Request.Url.Scheme + "://" + HttpContext.Request.Url.Authority + Url.Action("ResetPassword", "Account", new { key = randomString });

This way, a full URL is generated, and it works even if the application is several levels deep on the hosting server, and uses a port other than 80.

EDIT: I found this useful as well.

How to make rectangular image appear circular with CSS

I presume that your problem with background-image is that it would be inefficient with a source for each image inside a stylesheet. My suggestion is to set the source inline:

<div style = 'background-image: url(image.gif)'></div>

div {
    background-repeat: no-repeat;
    background-position: 50%;
    border-radius: 50%;
    width: 100px;
    height: 100px;
}

Fiddle

Send push to Android by C# using FCM (Firebase Cloud Messaging)

 public  SendNotice(int deviceType, string deviceToken, string message, int badge, int status, string sound)
    {
        AndroidFCMPushNotificationStatus result = new AndroidFCMPushNotificationStatus();
        try
        {
            result.Successful = false;
            result.Error = null;
            var value = message;
            WebRequest tRequest = WebRequest.Create("https://fcm.googleapis.com/fcm/send");
            tRequest.Method = "post";
            tRequest.ContentType = "application/json";
            var serializer = new JavaScriptSerializer();
            var json = "";
            tRequest.Headers.Add(string.Format("Authorization: key={0}", "AA******"));
            tRequest.Headers.Add(string.Format("Sender: id={0}", "11********"));
           if (DeviceType == 2)
            {
                var body = new
                  {
                      to = deviceToken,
                      data = new
                      {
                          custom_notification = new
                            {
                                title = "Notification",
                                body = message,
                                sound = "default",
                                priority = "high",
                                show_in_foreground = true,
                                targetScreen = notificationType,//"detail",
                                                                },
                      },

                      priority = 10
                  };

                json = serializer.Serialize(body);
            }
            else
            {
                var body = new
                {
                    to = deviceToken,
                    content_available = true,
                    notification = new
                    {
                        title = "Notification",
                        body = message,
                        sound = "default",
                        show_in_foreground = true,
                    },
                    data = new
                    {
                        targetScreen = notificationType,
                        id = 0,
                    },
                    priority = 10
                };
                json = serializer.Serialize(body);
            }

            Byte[] byteArray = Encoding.UTF8.GetBytes(json);

            tRequest.ContentLength = byteArray.Length;

            using (Stream dataStream = tRequest.GetRequestStream())
            {
                dataStream.Write(byteArray, 0, byteArray.Length);

                using (WebResponse tResponse = tRequest.GetResponse())
                {
                    using (Stream dataStreamResponse = tResponse.GetResponseStream())
                    {
                        using (StreamReader tReader = new StreamReader(dataStreamResponse))
                        {
                            String sResponseFromServer = tReader.ReadToEnd();
                            result.Response = sResponseFromServer;
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            result.Successful = false;
            result.Response = null;
            result.Error = ex;
        }
}

How to scroll to specific item using jQuery?

I did a combination of what others have posted. Its simple and smooth

 $('#myButton').click(function(){
        $('html, body').animate({
            scrollTop: $('#scroll-to-this-element').position().top },
            1000
        );
    });

Text in Border CSS HTML

I know a bit late to the party, however I feel the answers could do with some more investigation/input. I have managed to create the situation without using the fieldset tag - that is wrong anyway as if I'm not in a form then that isn't really what I should be doing.

_x000D_
_x000D_
/* Styles go here */

#info-block section {
    border: 2px solid black;
}

.file-marker > div {
    padding: 0 3px;
    height: 100px;
    margin-top: -0.8em;
    
}
.box-title {
    background: white none repeat scroll 0 0;
    display: inline-block;
    padding: 0 2px;
    margin-left: 8em;
}
_x000D_
<aside id="info-block">
  <section class="file-marker">
    <div>
      <div class="box-title">
        Audit Trail
      </div>
      <div class="box-contents">
        <div id="audit-trail">
        </div>
      </div>
    </div>
  </section>
</aside>
_x000D_
_x000D_
_x000D_

This can be viewed in this plunk:

Outline box with title

What this achieves is the following:

  • no use of fieldsets.

  • minimal use if CSS to create effect with just some paddings.

  • Use of "em" margin top to create font relative title.

  • use of display inline-block to achieve natural width around the text.

Anyway I hope that helps future stylers, you never know.

How to add a default "Select" option to this ASP.NET DropDownList control?

If you do an "Add" it will add it to the bottom of the list. You need to do an "Insert" if you want the item added to the top of the list.

Please explain the exec() function and its family

The exec family of functions make your process execute a different program, replacing the old program it was running. I.e., if you call

execl("/bin/ls", "ls", NULL);

then the ls program is executed with the process id, current working dir and user/group (access rights) of the process that called execl. Afterwards, the original program is not running anymore.

To start a new process, the fork system call is used. To execute a program without replacing the original, you need to fork, then exec.

How to know if two arrays have the same values

Simple solution for shallow equality using ES6:

const arr1test = arr1.slice().sort()
const arr2test = arr2.slice().sort()
const equal = !arr1test.some((val, idx) => val !== arr2test[idx])

Creates shallow copies of each array and sorts them. Then uses some() to loop through arr1test values, checking each value against the value in arr2test with the same index. If all values are equal, some() returns false, and in turn equal evaluates to true.

Could also use every(), but it would have to cycle through every element in the array to satisfy a true result, whereas some() will bail as soon as it finds a value that is not equal:

const equal = arr1test.every((val, idx) => val === arr2test[idx])

Get current NSDate in timestamp format

If you'd like to call this method directly on an NSDate object and get the timestamp as a string in milliseconds without any decimal places, define this method as a category:

@implementation NSDate (MyExtensions)
- (NSString *)unixTimestampInMilliseconds
{
     return [NSString stringWithFormat:@"%.0f", [self timeIntervalSince1970] * 1000];
}

html5 <input type="file" accept="image/*" capture="camera"> display as image rather than "choose file" button

You have to use Javascript Filereader for this. (Introduction into filereader-api: http://www.html5rocks.com/en/tutorials/file/dndfiles/)

Once the user have choose a image you can read the file-path of the chosen image and place it into your html.

Example:

<form id="form1" runat="server">
    <input type='file' id="imgInp" />
    <img id="blah" src="#" alt="your image" />
</form>

Javascript:

function readURL(input) {
    if (input.files && input.files[0]) {
        var reader = new FileReader();

        reader.onload = function (e) {
            $('#blah').attr('src', e.target.result);
        }

        reader.readAsDataURL(input.files[0]);
    }
}

$("#imgInp").change(function(){
    readURL(this);
});

How to set enum to null

You can either use the "?" operator for a nullable type.

public Color? myColor = null;

Or use the standard practice for enums that cannot be null by having the FIRST value in the enum (aka 0) be the default value. For example in a case of color None.

public Color myColor = Color.None;

how to add script src inside a View when using Layout

Depending how you want to implement it (if there was a specific location you wanted the scripts) you could implement a @section within your _Layout which would enable you to add additional scripts from the view itself, while still retaining structure. e.g.

_Layout

<!DOCTYPE html>
<html>
  <head>
    <title>...</title>
    <script src="@Url.Content("~/Scripts/jquery.min.js")"></script>
    @RenderSection("Scripts",false/*required*/)
  </head>
  <body>
    @RenderBody()
  </body>
</html>

View

@model MyNamespace.ViewModels.WhateverViewModel
@section Scripts
{
  <script src="@Url.Content("~/Scripts/jqueryFoo.js")"></script>
}

Otherwise, what you have is fine. If you don't mind it being "inline" with the view that was output, you can place the <script> declaration within the view.

Accessing Objects in JSON Array (JavaScript)

You can loop the array with a for loop and the object properties with for-in loops.

for (var i=0; i<result.length; i++)
    for (var name in result[i]) {
        console.log("Item name: "+name);
        console.log("Source: "+result[i][name].sourceUuid);
        console.log("Target: "+result[i][name].targetUuid);
    }

how to insert datetime into the SQL Database table?

myConn.Execute "INSERT INTO DayTr (dtID, DTSuID, DTDaTi, DTGrKg) VALUES (" & Val(txtTrNo) & "," & Val(txtCID) & ", '" & Format(txtTrDate, "yyyy-mm-dd") & "' ," & Val(Format(txtGross, "######0.00")) & ")"

Done in vb with all text type variables.

How to convert decimal to hexadecimal in JavaScript

Here's a trimmed down ECMAScript 6 version:

const convert = {
  bin2dec : s => parseInt(s, 2).toString(10),
  bin2hex : s => parseInt(s, 2).toString(16),
  dec2bin : s => parseInt(s, 10).toString(2),
  dec2hex : s => parseInt(s, 10).toString(16),
  hex2bin : s => parseInt(s, 16).toString(2),
  hex2dec : s => parseInt(s, 16).toString(10)
};

convert.bin2dec('111'); // '7'
convert.dec2hex('42');  // '2a'
convert.hex2bin('f8');  // '11111000'
convert.dec2bin('22');  // '10110'

How do I use an image as a submit button?

HTML:

<button type="submit" name="submit" class="button">
  <img src="images/free.png" />
</button>

CSS:

.button {  }

Does MS Access support "CASE WHEN" clause if connect with ODBC?

You could use IIF statement like in the next example:

SELECT
   IIF(test_expression, value_if_true, value_if_false) AS FIELD_NAME
FROM
   TABLE_NAME

Good Linux (Ubuntu) SVN client

For Ubuntu you cane make use of KDESVN integrated with Nautilus to five a Tortoise SVN Feel.

Try this ClickOffline.com : Ubuntu alternatives for Tortoise SVN

How to use WPF Background Worker

I found this (WPF Multithreading: Using the BackgroundWorker and Reporting the Progress to the UI. link) to contain the rest of the details which are missing from @Andrew's answer.

The one thing I found very useful was that the worker thread couldn't access the MainWindow's controls (in it's own method), however when using a delegate inside the main windows event handler it was possible.

worker.RunWorkerCompleted += delegate(object s, RunWorkerCompletedEventArgs args)
{
    pd.Close();
    // Get a result from the asynchronous worker
    T t = (t)args.Result
    this.ExampleControl.Text = t.BlaBla;
};

Why docker container exits immediately

whenever I want a container to stay up after finish the script execution I add

&& tail -f /dev/null

at the end of command. So it should be:

/usr/local/start-all.sh && tail -f /dev/null

Force sidebar height 100% using CSS (with a sticky bottom image)?

Further to @montrealmike 's answer, can I just add my adaptation?

I did this:

.container { 
  overflow: hidden; 
  .... 
} 

#sidebar { 
  margin-bottom: -101%;
  padding-bottom: 101%; 
  .... 
} 

I did the "101%" thing to cater for the (ultra rare) possibility that somebody may be viewing the site on a huge screen with a height more than 5000px!

Great answer though, montrealmike. It worked perfectly for me.

Get escaped URL parameter

There's a lot of buggy code here and regex solutions are very slow. I found a solution that works up to 20x faster than the regex counterpart and is elegantly simple:

    /*
    *   @param      string      parameter to return the value of.
    *   @return     string      value of chosen parameter, if found.
    */
    function get_param(return_this)
    {
        return_this = return_this.replace(/\?/ig, "").replace(/=/ig, ""); // Globally replace illegal chars.

        var url = window.location.href;                                   // Get the URL.
        var parameters = url.substring(url.indexOf("?") + 1).split("&");  // Split by "param=value".
        var params = [];                                                  // Array to store individual values.

        for(var i = 0; i < parameters.length; i++)
            if(parameters[i].search(return_this + "=") != -1)
                return parameters[i].substring(parameters[i].indexOf("=") + 1).split("+");

        return "Parameter not found";
    }

console.log(get_param("parameterName"));

Regex is not the be-all and end-all solution, for this type of problem simple string manipulation can work a huge amount more efficiently. Code source.

C# Copy a file to another location with a different name

If you want to use only FileInfo class try this

             string oldPath = @"C:\MyFolder\Myfile.xyz";
             string newpath = @"C:\NewFolder\";
             string newFileName = "new file name";
             FileInfo f1 = new FileInfo(oldPath);
           if(f1.Exists)
             {
                if(!Directory.Exists(newpath))
                {
                    Directory.CreateDirectory(newpath); 
                }
                 f1.CopyTo(string.Format("{0}{1}{2}", newpath, newFileName, f1.Extension));
             }

How to hide scrollbar in Firefox?

For more recent version of Firefox the old solutions don't work anymore, but I did succesfully used in v66.0.3 the scrollbar-color property which you can set to transparent transparent and which will make the scrollbar in Firefox on the desktop at least invisible (still takes place in the viewport and on mobile doesn't work, but there the scrollbar is a fine line that is placed over the content on the right).

overflow-y: auto; //or hidden if you don't want horizontal scrolling
overflow-y: auto;
scrollbar-color: transparent transparent;

How to align iframe always in the center

Very easy:

  1. you have only to place the iframe between

     <center> ...  </center>
    
  2. with some

     <br>
    

. That's all.

How do I view the list of functions a Linux shared library is exporting?

On a MAC, you need to use nm *.o | c++filt, as there is no -C option in nm.

JNZ & CMP Assembly Instructions

JNZ     Jump if Not Zero    ZF=0

Indeed, this is confusing right.

To make it easier to understand, replace Not Zero with Not Set. (Please take note this is for your own understanding)

Hence,

JNZ     Jump if Not Set     ZF=0

Not Set means flag Z = 0. So Jump (Jump if Not Set)

Set means flag Z = 1. So, do NOT Jump

SQL Query - SUM(CASE WHEN x THEN 1 ELSE 0) for multiple columns

I would change the query in the following ways:

  1. Do the aggregation in subqueries. This can take advantage of more information about the table for optimizing the group by.
  2. Combine the second and third subqueries. They are aggregating on the same column. This requires using a left outer join to ensure that all data is available.
  3. By using count(<fieldname>) you can eliminate the comparisons to is null. This is important for the second and third calculated values.
  4. To combine the second and third queries, it needs to count an id from the mde table. These use mde.mdeid.

The following version follows your example by using union all:

SELECT CAST(Detail.ReceiptDate AS DATE) AS "Date",
       SUM(TOTALMAILED) as TotalMailed,
       SUM(TOTALUNDELINOTICESRECEIVED) as TOTALUNDELINOTICESRECEIVED,
       SUM(TRACEUNDELNOTICESRECEIVED) as TRACEUNDELNOTICESRECEIVED
FROM ((select SentDate AS "ReceiptDate", COUNT(*) as TotalMailed,
              NULL as TOTALUNDELINOTICESRECEIVED, NULL as TRACEUNDELNOTICESRECEIVED
       from MailDataExtract
       where SentDate is not null
       group by SentDate
      ) union all
      (select MDE.ReturnMailDate AS ReceiptDate, 0,
              COUNT(distinct mde.mdeid) as TOTALUNDELINOTICESRECEIVED,
              SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
       from MailDataExtract MDE left outer join
            DTSharedData.dbo.ScanData SD
            ON SD.ScanDataID = MDE.ReturnScanDataID
       group by MDE.ReturnMailDate;
      )
     ) detail
GROUP BY CAST(Detail.ReceiptDate AS DATE)
ORDER BY 1;

The following does something similar using full outer join:

SELECT coalesce(sd.ReceiptDate, mde.ReceiptDate) AS "Date",
       sd.TotalMailed, mde.TOTALUNDELINOTICESRECEIVED,
       mde.TRACEUNDELNOTICESRECEIVED
FROM (select cast(SentDate as date) AS "ReceiptDate", COUNT(*) as TotalMailed
      from MailDataExtract
      where SentDate is not null
      group by cast(SentDate as date)
     ) sd full outer join
    (select cast(MDE.ReturnMailDate as date) AS ReceiptDate,
            COUNT(distinct mde.mdeID) as TOTALUNDELINOTICESRECEIVED,
            SUM(case when sd.ReturnMailTypeId = 1 then 1 else 0 end) as TRACEUNDELNOTICESRECEIVED
     from MailDataExtract MDE left outer join
          DTSharedData.dbo.ScanData SD
          ON SD.ScanDataID = MDE.ReturnScanDataID
     group by cast(MDE.ReturnMailDate as date)
    ) mde
    on sd.ReceiptDate = mde.ReceiptDate
ORDER BY 1;

Redirecting a page using Javascript, like PHP's Header->Location

The PHP code is executed on the server, so your redirect is executed before the browser even sees the JavaScript.

You need to do the redirect in JavaScript too

$('.entry a:first').click(function()
{
    window.location.replace("http://www.google.com");
});

jQuery Datepicker onchange event issue

$('#inputfield').change(function() { 
    dosomething();
});

Has anyone ever got a remote JMX JConsole to work?

I am running JConsole/JVisualVm on windows hooking to tomcat running Linux Redhat ES3.

Disabling packet filtering using the following command did the trick for me:

/usr/sbin/iptables -I INPUT -s jconsole-host -p tcp --destination-port jmxremote-port -j ACCEPT

where jconsole-host is either the hostname or the host address on which JConsole runs on and jmxremote-port is the port number set for com.sun.management.jmxremote.port for remote management.

Setting the default ssh key location

If you are only looking to point to a different location for you identity file, the you can modify your ~/.ssh/config file with the following entry:

IdentityFile ~/.foo/identity

man ssh_config to find other config options.

yii2 redirect in controller action does not work?

In Yii2 we need to return() the result from the action.I think you need to add a return in front of your redirect.

  return $this->redirect(['user/index']);

What are all the possible values for HTTP "Content-Type" header?

As is defined in RFC 1341:

In the Extended BNF notation of RFC 822, a Content-Type header field value is defined as follows:

Content-Type := type "/" subtype *[";" parameter]

type := "application" / "audio" / "image" / "message" / "multipart" / "text" / "video" / x-token

x-token := < The two characters "X-" followed, with no intervening white space, by any token >

subtype := token

parameter := attribute "=" value

attribute := token

value := token / quoted-string

token := 1*

tspecials := "(" / ")" / "<" / ">" / "@" ; Must be in / "," / ";" / ":" / "\" / <"> ; quoted-string, / "/" / "[" / "]" / "?" / "." ; to use within / "=" ; parameter values

And a list of known MIME types that can follow it (or, as Joe remarks, the IANA source).

As you can see the list is way too big for you to validate against all of them. What you can do is validate against the general format and the type attribute to make sure that is correct (the set of options is small) and just assume that what follows it is correct (and of course catch any exceptions you might encounter when you put it to actual use).

Also note the comment above:

If another primary type is to be used for any reason, it must be given a name starting with "X-" to indicate its non-standard status and to avoid any potential conflict with a future official name.

You'll notice that a lot of HTTP requests/responses include an X- header of some sort which are self defined, keep this in mind when validating the types.

How to style input and submit button with CSS?

Very simple:

<html>
<head>
<head>
<style type="text/css">
.buttonstyle 
{ 
background: black; 
background-position: 0px -401px; 
border: solid 1px #000000; 
color: #ffffff;
height: 21px;
margin-top: -1px;
padding-bottom: 2px;
}
.buttonstyle:hover {background: white;background-position: 0px -501px;color: #000000; }
</style>
</head>
<body>
<form>
<input class="buttonstyle" type="submit" name="submit" Value="Add Items"/>
</form>
</body>
</html>

This is working I have tested.

Cannot implicitly convert type 'int' to 'short'

That's because the result of adding two Int16 is an Int32. Check the "conversions" paragraph here: http://msdn.microsoft.com/en-us/library/ybs77ex4%28v=vs.71%29.aspx

How to get HttpClient returning status code and response body?

BasicResponseHandler throws if the status is not 2xx. See its javadoc.

Here is how I would do it:

HttpResponse response = client.execute( get );
int code = response.getStatusLine().getStatusCode();
InputStream body = response.getEntity().getContent();
// Read the body stream

Or you can also write a ResponseHandler starting from BasicResponseHandler source that don't throw when the status is not 2xx.

WPF Check box: Check changed handling

That you can handle the checked and unchecked events seperately doesn't mean you have to. If you don't want to follow the MVVM pattern you can simply attach the same handler to both events and you have your change signal:

<CheckBox Checked="CheckBoxChanged" Unchecked="CheckBoxChanged"/>

and in Code-behind;

private void CheckBoxChanged(object sender, RoutedEventArgs e)
{
  MessageBox.Show("Eureka, it changed!");
}

Please note that WPF strongly encourages the MVVM pattern utilizing INotifyPropertyChanged and/or DependencyProperties for a reason. This is something that works, not something I would like to encourage as good programming habit.

How to handle command-line arguments in PowerShell

You are reinventing the wheel. Normal PowerShell scripts have parameters starting with -, like script.ps1 -server http://devserver

Then you handle them in param section in the beginning of the file.

You can also assign default values to your params, read them from console if not available or stop script execution:

 param (
    [string]$server = "http://defaultserver",
    [Parameter(Mandatory=$true)][string]$username,
    [string]$password = $( Read-Host "Input password, please" )
 )

Inside the script you can simply

write-output $server

since all parameters become variables available in script scope.

In this example, the $server gets a default value if the script is called without it, script stops if you omit the -username parameter and asks for terminal input if -password is omitted.

Update: You might also want to pass a "flag" (a boolean true/false parameter) to a PowerShell script. For instance, your script may accept a "force" where the script runs in a more careful mode when force is not used.

The keyword for that is [switch] parameter type:

 param (
    [string]$server = "http://defaultserver",
    [string]$password = $( Read-Host "Input password, please" ),
    [switch]$force = $false
 )

Inside the script then you would work with it like this:

if ($force) {
  //deletes a file or does something "bad"
}

Now, when calling the script you'd set the switch/flag parameter like this:

.\yourscript.ps1 -server "http://otherserver" -force

If you explicitly want to state that the flag is not set, there is a special syntax for that

.\yourscript.ps1 -server "http://otherserver" -force:$false

Links to relevant Microsoft documentation (for PowerShell 5.0; tho versions 3.0 and 4.0 are also available at the links):

How can I represent an infinite number in Python?

Also if you use SymPy you can use sympy.oo

>>> from sympy import oo
>>> oo + 1
oo
>>> oo - oo
nan

etc.

Pandas: Looking up the list of sheets in an excel file

If you:

  • care about performance
  • don't need the data in the file at execution time.
  • want to go with conventional libraries vs rolling your own solution

Below was benchmarked on a ~10Mb xlsx, xlsb file.

xlsx, xls

from openpyxl import load_workbook

def get_sheetnames_xlsx(filepath):
    wb = load_workbook(filepath, read_only=True, keep_links=False)
    return wb.sheetnames

Benchmarks: ~ 14x speed improvement

# get_sheetnames_xlsx vs pd.read_excel
225 ms ± 6.21 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
3.25 s ± 140 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

xlsb

from pyxlsb import open_workbook

def get_sheetnames_xlsb(filepath):
  with open_workbook(filepath) as wb:
     return wb.sheets

Benchmarks: ~ 56x speed improvement

# get_sheetnames_xlsb vs pd.read_excel
96.4 ms ± 1.61 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
5.36 s ± 162 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

Notes:

C# Wait until condition is true

you can use SpinUntil which is buildin in the .net-framework. Please note: This method causes high cpu-workload.

Center form submit buttons HTML / CSS

Try this :

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<head>
    <style type="text/css">
        #btn_s{
            width:100px;
        }

        #btn_i {
            width:125px;
        }
        #formbox {
            width:400px;
            margin:auto 0;
            text-align: center;
        }
    </style>
</head>
<body>
    <form method="post" action="">
        <div id="formbox">
            <input value="Search" title="Search" type="submit" id="btn_s"> 
            <input value="I'm Feeling Lucky" title="I'm Feeling Lucky" name="lucky" type="submit" id="btn_i">
        </div>
    </form>
</body>

This has 2 examples, you can use the one that fits best in your situation.

  • use text-align:center on the parent container, or create a container for this.
  • if the container has to have a fixed size, use auto left and right margins to center it in the parent container.

note that auto is used with single blocks to center them in the parent space by distrubuting the empty space to the left and right.

How can I shutdown Spring task executor/scheduler pools before all other beans in the web app are destroyed?

If it is going to be a web based application, you can also use the ServletContextListener interface.

public class SLF4JBridgeListener implements ServletContextListener {

   @Autowired 
   ThreadPoolTaskExecutor executor;

   @Autowired 
   ThreadPoolTaskScheduler scheduler;

    @Override
    public void contextInitialized(ServletContextEvent sce) {

    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
         scheduler.shutdown();
         executor.shutdown();     

    }

}

Reading a simple text file

Place your text file in the /assets directory under the Android project. Use AssetManager class to access it.

AssetManager am = context.getAssets();
InputStream is = am.open("test.txt");

Or you can also put the file in the /res/raw directory, where the file will be indexed and is accessible by an id in the R file:

InputStream is = context.getResources().openRawResource(R.raw.test);

XAMPP, Apache - Error: Apache shutdown unexpectedly

In my case, this issue was caused by an attempt to download other product of bitnami, like WordPress. That's common when we install WordPress via XAMPP. It is placed in the xampp/app directory that can be accessed from the XAMPP application homepage.

As a solution, I removed the default installed WordPress from the xampp directory and manually installed WordPress in the htdocs folder of WordPress by downloading it and extracting zip files into the htdoc folder. You also need to restart XAMPP or may system after uninstalling/removing the default WordPress. All is OK for me now.

Error:Unable to locate adb within SDK in Android Studio

I know this is silly, but in my case while I was getting the same error message, just changing the USB cable used to connect the device fixed the problem :O

Perhaps this might benefit someone else as well?!

What is the difference between association, aggregation and composition?

Dependency (references)
It means there is no conceptual link between two objects. e.g. EnrollmentService object references Student & Course objects (as method parameters or return types)

public class EnrollmentService {
    public void enroll(Student s, Course c){}
}

Association (has-a)
It means there is almost always a link between objects (they are associated). Order object has a Customer object

public class Order {
    private Customer customer
}

Aggregation (has-a + whole-part)
Special kind of association where there is whole-part relation between two objects. they might live without each other though.

public class PlayList {
    private List<Song> songs;
}

OR

public class Computer {
    private Monitor monitor;
}

Note: the trickiest part is to distinguish aggregation from normal association. Honestly, I think this is open to different interpretations.

Composition (has-a + whole-part + ownership)
Special kind of aggregation. An Apartment is composed of some Rooms. A Room cannot exist without an Apartment. when an apartment is deleted, all associated rooms are deleted as well.

public class Apartment{
    private Room bedroom;
    public Apartment() {
       bedroom = new Room();
    }
}

HTML input field hint

the best way to give a hint is placeholder like this:

<input.... placeholder="hint".../>

NSDate get year/month/day

I'm writing this answer because it's the only approach that doesn't give you optionals back from NSDateComponent variables and/or force unwrapping those variables (also for Swift 3).

Swift 3

let date = Date()
let cal = Calendar.current
let year = cal.component(.year, from: date)
let month = cal.component(.month, from: date)
let day = cal.component(.day, from: date)

Swift 2

let date = NSDate()
let cal = NSCalendar.currentCalendar()
let year = cal.component(.Year, fromDate: date)
let month = cal.component(.Month, fromDate: date)
let day = cal.component(.Day, fromDate: date)

Bonus Swift 3 fun version

let date = Date()
let component = { (unit) in return Calendar.current().component(unit, from: date) }
let year = component(.year)
let month = component(.month)
let day = component(.day)

How to display gpg key details without importing it?

I seem to be able to get along with simply:

$gpg <path_to_file>

Which outputs like this:

$ gpg /tmp/keys/something.asc 
  pub  1024D/560C6C26 2014-11-26 Something <[email protected]>
  sub  2048g/0C1ACCA6 2014-11-26

The op didn't specify in particular what key info is relevant. This output is all I care about.

Any way to select without causing locking in MySQL?

Found an article titled "MYSQL WITH NOLOCK"

https://web.archive.org/web/20100814144042/http://sqldba.org/articles/22-mysql-with-nolock.aspx

in MS SQL Server you would do the following:

SELECT * FROM TABLE_NAME WITH (nolock)

and the MYSQL equivalent is

SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ;
SELECT * FROM TABLE_NAME ;
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ ;

EDIT

Michael Mior suggested the following (from the comments)

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ;
SELECT * FROM TABLE_NAME ;
COMMIT ;

Databinding an enum property to a ComboBox in WPF

you can consider something like that:

  1. define a style for textblock, or any other control you want to use to display your enum:

    <Style x:Key="enumStyle" TargetType="{x:Type TextBlock}">
        <Setter Property="Text" Value="&lt;NULL&gt;"/>
        <Style.Triggers>
            <Trigger Property="Tag">
                <Trigger.Value>
                    <proj:YourEnum>Value1<proj:YourEnum>
                </Trigger.Value>
                <Setter Property="Text" Value="{DynamicResource yourFriendlyValue1}"/>
            </Trigger>
            <!-- add more triggers here to reflect your enum -->
        </Style.Triggers>
    </Style>
    
  2. define your style for ComboBoxItem

    <Style TargetType="{x:Type ComboBoxItem}">
        <Setter Property="ContentTemplate">
            <Setter.Value>
                <DataTemplate>
                    <TextBlock Tag="{Binding}" Style="{StaticResource enumStyle}"/>
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>
    
  3. add a combobox and load it with your enum values:

    <ComboBox SelectedValue="{Binding Path=your property goes here}" SelectedValuePath="Content">
        <ComboBox.Items>
            <ComboBoxItem>
                <proj:YourEnum>Value1</proj:YourEnum>
            </ComboBoxItem>
        </ComboBox.Items>
    </ComboBox>
    

if your enum is large, you can of course do the same in code, sparing a lot of typing. i like that approach, since it makes localization easy - you define all the templates once, and then, you only update your string resource files.

What is char ** in C?

Technically, the char* is not an array, but a pointer to a char.

Similarly, char** is a pointer to a char*. Making it a pointer to a pointer to a char.

C and C++ both define arrays behind-the-scenes as pointer types, so yes, this structure, in all likelihood, is array of arrays of chars, or an array of strings.

How can I get the Windows last reboot reason

This article explains in detail how to find the reason for last startup/shutdown. In my case, this was due to windows SCCM pushing updates even though I had it disabled locally. Visit the article for full details with pictures. For reference, here are the steps copy/pasted from the website:

  1. Press the Windows + R keys to open the Run dialog, type eventvwr.msc, and press Enter.

  2. If prompted by UAC, then click/tap on Yes (Windows 7/8) or Continue (Vista).

  3. In the left pane of Event Viewer, double click/tap on Windows Logs to expand it, click on System to select it, then right click on System, and click/tap on Filter Current Log.

  4. Do either step 5 or 6 below for what shutdown events you would like to see.

  5. To See the Dates and Times of All User Shut Downs of the Computer

    A) In Event sources, click/tap on the drop down arrow and check the USER32 box.

    B) In the All Event IDs field, type 1074, then click/tap on OK.

    C) This will give you a list of power off (shutdown) and restart Shutdown Type of events at the top of the middle pane in Event Viewer.

    D) You can scroll through these listed events to find the events with power off as the Shutdown Type. You will notice the date and time, and what user was responsible for shutting down the computer per power off event listed.

    E) Go to step 7.

  6. To See the Dates and Times of All Unexpected Shut Downs of the Computer

    A) In the All Event IDs field, type 6008, then click/tap on OK.

    B) This will give you a list of unexpected shutdown events at the top of the middle pane in Event Viewer. You can scroll through these listed events to see the date and time of each one.

Why doesn't importing java.util.* include Arrays and Lists?

Case 1 should have worked. I don't see anything wrong. There may be some other problems. I would suggest a clean build.

Git checkout - switching back to HEAD

You can stash (save the changes in temporary box) then, back to master branch HEAD.

$ git add .
$ git stash
$ git checkout master

Jump Over Commits Back and Forth:

  • Go to a specific commit-sha.

      $ git checkout <commit-sha>
    
  • If you have uncommitted changes here then, you can checkout to a new branch | Add | Commit | Push the current branch to the remote.

      # checkout a new branch, add, commit, push
      $ git checkout -b <branch-name>
      $ git add .
      $ git commit -m 'Commit message'
      $ git push origin HEAD          # push the current branch to remote 
    
      $ git checkout master           # back to master branch now
    
  • If you have changes in the specific commit and don't want to keep the changes, you can do stash or reset then checkout to master (or, any other branch).

      # stash
      $ git add -A
      $ git stash
      $ git checkout master
    
      # reset
      $ git reset --hard HEAD
      $ git checkout master
    
  • After checking out a specific commit if you have no uncommitted change(s) then, just back to master or other branch.

      $ git status          # see the changes
      $ git checkout master
    
      # or, shortcut
      $ git checkout -      # back to the previous state
    

How to display .svg image using swift

SVG file support is added to Xcode 12.

enter image description here

What do the result codes in SVN mean?

SVN status columns

$ svn status
L index.html

The output of the command is split into six columns, but that is not obvious because sometimes the columns are empty. Perhaps it would have made more sense to indicate the empty columns with dashes, the way ls -l does, instead of nothing. Then, for example, L index.html would look like --L--- index.html, which makes it obvious the only information we have is in the third column the one about locking. Anyway, once you know that it begins to make more sense.

SVN Status first column: A, D, M, R, C, X, I, ?, !, ~

The first column indicates that an item was added, deleted, or otherwise changed.

      No modifications.

 A    Item is scheduled for Addition.

 D    Item is scheduled for Deletion.

 M    Item has been modified.

 R    Item has been replaced in your working copy. This means the file was scheduled for deletion, and then a new file with the same name was scheduled for addition in its place.

 C    The contents (as opposed to the properties) of the item conflict with updates received from the repository.

 X    Item is related to an externals definition.

 I    Item is being ignored (e.g. with the svn:ignore property).

 ?    Item is not under version control.

 !    Item is missing (e.g. you moved or deleted it without using svn). This also indicates that a directory is incomplete (a checkout or update was interrupted).

 ~    Item is versioned as one kind of object (file, directory, link), but has been replaced by different kind of object.

SVN Status second column: M, C

The second column tells the status of a file’s or directory’s properties.

      No modifications.

 M    Properties for this item have been modified.

 C    Properties for this item are in conflict with property updates received from the repository.

SVN Status third column: L

The third column is populated only if the working copy directory is locked (an svn cleanup should normally be enough to clear it out)

      Item is not locked.

 L    Item is locked.

SVN Status fourth column: +

The fourth column is populated only if the item is scheduled for addition-with-history.

      No history scheduled with commit.

 +    History scheduled with commit.

SVN Status fifth column: S

The fifth column is populated only if the item’s working copy is switched relative to its parent

      Item is a child of its parent directory.

 S    Item is switched.

SVN Status sixth column: K, O, T, B

The sixth column is populated with lock information.

      When –show-updates is used, the file is not locked. If –show-updates is not used, this merely means that the file is not locked in this working copy.

 K    File is locked in this working copy.

 O    File is locked either by another user or in another working copy. This only appears when –show-updates is used.

 T    File was locked in this working copy, but the lock has been stolen and is invalid. The file is currently locked in the repository. This only appears when –show-updates is used.-

 B    File was locked in this working copy, but the lock has been broken and is invalid. The file is no longer locked This only appears when –show-updates is used.

SVN Status seventh column: *

The out-of-date information appears in the seventh column (only if you pass the –show-updates switch). This is something people who are new to SVN expect the command to do, not realizing it only compare the current state of the file with what information it fetched from the server on the last update.

      The item in your working copy is up-to-date.

 *    A newer revision of the item exists on the server.

AttributeError: 'module' object has no attribute 'urlopen'

For python 3, try something like this:

import urllib.request
urllib.request.urlretrieve('http://crcv.ucf.edu/THUMOS14/UCF101/UCF101/v_YoYo_g19_c02.avi', "video_name.avi")

It will download the video to the current working directory

I got help from HERE