Programs & Examples On #Transitivity

Java: JSON -> Protobuf & back conversion

Try JsonFormat.printer().print(MessageOrBuilder), it looks good for proto3. Yet, it is unclear how to convert the actual protobuf message (which is provided as the java package of my choice defined in the .proto file) to a com.google.protbuf.Message object.

How to extend a class in python?

Another way to extend (specifically meaning, add new methods, not change existing ones) classes, even built-in ones, is to use a preprocessor that adds the ability to extend out of/above the scope of Python itself, converting the extension to normal Python syntax before Python actually gets to see it.

I've done this to extend Python 2's str() class, for instance. str() is a particularly interesting target because of the implicit linkage to quoted data such as 'this' and 'that'.

Here's some extending code, where the only added non-Python syntax is the extend:testDottedQuad bit:

extend:testDottedQuad
def testDottedQuad(strObject):
    if not isinstance(strObject, basestring): return False
    listStrings = strObject.split('.')
    if len(listStrings) != 4: return False
    for strNum in listStrings:
        try:    val = int(strNum)
        except: return False
        if val < 0: return False
        if val > 255: return False
    return True

After which I can write in the code fed to the preprocessor:

if '192.168.1.100'.testDottedQuad():
    doSomething()

dq = '216.126.621.5'
if not dq.testDottedQuad():
    throwWarning();

dqt = ''.join(['127','.','0','.','0','.','1']).testDottedQuad()
if dqt:
    print 'well, that was fun'

The preprocessor eats that, spits out normal Python without monkeypatching, and Python does what I intended it to do.

Just as a c preprocessor adds functionality to c, so too can a Python preprocessor add functionality to Python.

My preprocessor implementation is too large for a stack overflow answer, but for those who might be interested, it is here on GitHub.

Automatically scroll down chat div

Dont have to mix jquery and javascript. Use like this,

function getMessages(letter) {
    var message=$('#messages');
    $.get('msg_show.php', function(data) {
        message.html(data);
        message.scrollTop(message[0].scrollHeight);
    });
}

setInterval(function() {
    getMessages("letter");
}, 100)

Put the scrollTop() inside get() method.

Also you missed a parameter in the getMessage method call..

How to export iTerm2 Profiles

There is another way to do this.

From iTerm2 2.9.20140923 you can use Dynamic Profiles as stated in the documentation page:

Dynamic Profiles is a feature that allows you to store your profiles in a file outside the usual macOS preferences database. Profiles may be changed at runtime by editing one or more plist files (formatted as JSON, XML, or in binary). Changes are picked up immediately.

So it is possible to create a file like this one:

    {
        "Profiles": [{
                "Name": "MYSERVER1",
                "Guid": "MYSERVER1",
                "Custom Command": "Yes",
                "Command": "ssh [email protected]",
                "Shortcut": "M",
                "Tags": [
                    "LOCAL", "THATCOMPANY", "WORK", "NOCLOUD"
                ],
                "Badge Text": "SRV1",
            },
            {
                "Name": "MYOCEANSERVER1",
                "Guid": "MYOCEANSERVER1",
                "Custom Command": "Yes",
                "Command": "ssh [email protected]",
                "Shortcut": "O",
                "Tags": [
                    "THATCOMPANY", "WORK", "DIGITALOCEAN"
                ],
                "Badge Text": "PPOCEAN1",
            },
            {
                "Name": "PI1",
                "Guid": "PI1",
                "Custom Command": "Yes",
                "Command": "ssh [email protected]",
                "Shortcut": "1",
                "Tags": [
                    "LOCAL", "PERSONAL", "RASPBERRY", "SMALL"
                ],
                "Badge Text": "LocalServer",
            },
            {
                "Name": "VUZERO",
                "Guid": "VUZERO",
                "Custom Command": "Yes",
                "Command": "ssh [email protected]",
                "Shortcut": "0",
                "Tags": [
                    "LOCAL", "PERSONAL", "SMALL"
                ],
                "Badge Text": "TeleVision",
            }
        ]
    }

in the folder ~/Library/Application\ Support/iTerm2/DynamicProfiles/ and share it across different machines. This enables you to retain some visual differences among iterm2 installations such as font type or dimension, while synchronising remote hosts, shortcuts, commands, and even a small badge to quickly identify a session

badge

React: why child component doesn't update when prop changes

Confirmed, adding a Key works. I went through the docs to try and understand why.

React wants to be efficient when creating child components. It won't render a new component if it's the same as another child, which makes the page load faster.

Adding a Key forces React to render a new component, thus resetting State for that new component.

https://reactjs.org/docs/reconciliation.html#recursing-on-children

How to set only time part of a DateTime variable in C#

you can't change the DateTime object, it's immutable. However, you can set it to a new value, for example:

var newDate = oldDate.Date + new TimeSpan(11, 30, 55);

How can I check the size of a file in a Windows batch script?

%~z1 expands to the size of the first argument to the batch file. See

C:\> call /?

and

C:\> if /?

Simple example:

@ECHO OFF
SET SIZELIMIT=1000
SET FILESIZE=%~z1

IF %FILESIZE% GTR %SIZELIMIT% Goto No

ECHO Great! Your filesize is smaller than %SIZELIMIT% kbytes.
PAUSE
GOTO :EOF

:No
ECHO Um ... You have a big filesize.
PAUSE
GOTO :EOF

Find provisioning profile in Xcode 5

You can use "iPhone Configuration Utility" to manage provisioning profiles.

Converting Columns into rows with their respective data in sql server

select 'ScriptName', scriptName from table
union all
select 'ScriptCode', scriptCode from table
union all
select 'Price', price from table

Get number of digits with JavaScript

Here's a mathematical answer (also works for negative numbers):

function numDigits(x) {
  return Math.max(Math.floor(Math.log10(Math.abs(x))), 0) + 1;
}

And an optimized version of the above (more efficient bitwise operations):

function numDigits(x) {
  return (Math.log10((x ^ (x >> 31)) - (x >> 31)) | 0) + 1;
}

Essentially, we start by getting the absolute value of the input to allow negatives values to work correctly. Then we run the through the log10 operation to give us what power of 10 the input is (if you were working in another base, you would use the logarithm for that base), which is the number of digits. Then we floor the output to only grab the integer part of that. Finally, we use the max function to fix decimal values (any fractional value between 0 and 1 just returns 1, instead of a negative number), and add 1 to the final output to get the count.

The above assumes (based on your example input) that you wish to count the number of digits in integers (so 12345 = 5, and thus 12345.678 = 5 as well). If you would like to count the total number of digits in the value (so 12345.678 = 8), then add this before the 'return' in either function above:

x = Number(String(x).replace(/[^0-9]/g, ''));

How to convert JSON to CSV format and store in a variable

Heres a way to do it for dynamically deep objects in a object oriented way for the newer js versions. you might have to change the seperatortype after region.

private ConvertToCSV(objArray) {
    let rows = typeof objArray !== "object" ? JSON.parse(objArray) : objArray;
    let  header = "";
    Object.keys(rows[0]).map(pr => (header += pr + ";"));

    let str = "";
    rows.forEach(row => {
        let line = "";
        let columns =
            typeof row !== "object" ? JSON.parse(row) : Object.values(row);
        columns.forEach(column => {
            if (line !== "") {
                line += ";";
            }
            if (typeof column === "object") {
                line += JSON.stringify(column);
            }  else {
                line += column;
            }
        });
        str += line + "\r\n";
    });
    return header + "\r\n" + str;
}

Setting environment variables in Linux using Bash

export VAR=value will set VAR to value. Enclose it in single quotes if you want spaces, like export VAR='my val'. If you want the variable to be interpolated, use double quotes, like export VAR="$MY_OTHER_VAR".

How to grep recursively, but only in files with certain extensions?

There is no -r option on HP and Sun servers, this way worked for me on my HP server

find . -name "*.c" | xargs grep -i "my great text"

-i is for case insensitive search of string

Leaflet changing Marker color

A cheap way to change the Leaflet marker colour is to use the CSS filter property. Give the icon an extra class and then change its colour in the stylesheet:

<style>
img.huechange { filter: hue-rotate(120deg); }
</style>
<script>
var marker = L.marker([y, x]).addTo(map);
marker._icon.classList.add("huechange");
</script>

and this will produce a red marker: alter the value given to hue-rotate to alter the colour.

enter image description here

When using Trusted_Connection=true and SQL Server authentication, will this affect performance?

Not 100% sure what you mean:

Trusted_Connection=True;

IS using Windows credentials and is 100% equivalent to:

Integrated Security=SSPI;

or

Integrated Security=true;

If you don't want to use integrated security / trusted connection, you need to specify user id and password explicitly in the connection string (and leave out any reference to Trusted_Connection or Integrated Security)

server=yourservername;database=yourdatabase;user id=YourUser;pwd=TopSecret

Only in this case, the SQL Server authentication mode is used.

If any of these two settings is present (Trusted_Connection=true or Integrated Security=true/SSPI), then the Windows credentials of the current user are used to authenticate against SQL Server and any user iD= setting will be ignored and not used.

For reference, see the Connection Strings site for SQL Server 2005 with lots of samples and explanations.

Using Windows Authentication is the preferred and recommended way of doing things, but it might incur a slight delay since SQL Server would have to authenticate your credentials against Active Directory (typically). I have no idea how much that slight delay might be, and I haven't found any references for that.


Summing up:

If you specify either Trusted_Connection=True; or Integrated Security=SSPI; or Integrated Security=true; in your connection string

==> THEN (and only then) you have Windows Authentication happening. Any user id= setting in the connection string will be ignored.


If you DO NOT specify either of those settings,

==> then you DO NOT have Windows Authentication happening (SQL Authentication mode will be used)


Simple http post example in Objective-C?

You can do using two options:

Using NSURLConnection:

NSURL* URL = [NSURL URLWithString:@"http://www.example.com/path"];
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:URL];
request.HTTPMethod = @"POST";
// Form URL-Encoded Body

NSDictionary* bodyParameters = @{
    @"username": @"reallyrambody",
    @"password": @"123456"
};
request.HTTPBody = [NSStringFromQueryParameters(bodyParameters) dataUsingEncoding:NSUTF8StringEncoding];

// Connection

NSURLConnection* connection = [NSURLConnection connectionWithRequest:request delegate:nil];
[connection start];

/*
 * Utils: Add this section before your class implementation
 */

/**
 This creates a new query parameters string from the given NSDictionary. For
 example, if the input is @{@"day":@"Tuesday", @"month":@"January"}, the output
 string will be @"day=Tuesday&month=January".
 @param queryParameters The input dictionary.
 @return The created parameters string.
*/
static NSString* NSStringFromQueryParameters(NSDictionary* queryParameters)
{
    NSMutableArray* parts = [NSMutableArray array];
    [queryParameters enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL *stop) {
        NSString *part = [NSString stringWithFormat: @"%@=%@",
            [key stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding],
            [value stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding]
        ];
        [parts addObject:part];
    }];
    return [parts componentsJoinedByString: @"&"];
}

/**
 Creates a new URL by adding the given query parameters.
 @param URL The input URL.
 @param queryParameters The query parameter dictionary to add.
 @return A new NSURL.
*/
static NSURL* NSURLByAppendingQueryParameters(NSURL* URL, NSDictionary* queryParameters)
{
    NSString* URLString = [NSString stringWithFormat:@"%@?%@",
        [URL absoluteString],
        NSStringFromQueryParameters(queryParameters)
    ];
    return [NSURL URLWithString:URLString];
}

Using NSURLSession

- (void)sendRequest:(id)sender
{
    /* Configure session, choose between:
       * defaultSessionConfiguration
       * ephemeralSessionConfiguration
       * backgroundSessionConfigurationWithIdentifier:
     And set session-wide properties, such as: HTTPAdditionalHeaders,
     HTTPCookieAcceptPolicy, requestCachePolicy or timeoutIntervalForRequest.
     */
    NSURLSessionConfiguration* sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];

    /* Create session, and optionally set a NSURLSessionDelegate. */
    NSURLSession* session = [NSURLSession sessionWithConfiguration:sessionConfig delegate:nil delegateQueue:nil];

    /* Create the Request:
       Token Duplicate (POST http://www.example.com/path)
     */

    NSURL* URL = [NSURL URLWithString:@"http://www.example.com/path"];
    NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:URL];
    request.HTTPMethod = @"POST";

    // Form URL-Encoded Body

    NSDictionary* bodyParameters = @{
        @"username": @"reallyram",
        @"password": @"123456"
    };
    request.HTTPBody = [NSStringFromQueryParameters(bodyParameters) dataUsingEncoding:NSUTF8StringEncoding];

    /* Start a new Task */
    NSURLSessionDataTask* task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error == nil) {
            // Success
            NSLog(@"URL Session Task Succeeded: HTTP %ld", ((NSHTTPURLResponse*)response).statusCode);
        }
        else {
            // Failure
            NSLog(@"URL Session Task Failed: %@", [error localizedDescription]);
        }
    }];
    [task resume];
}

/*
 * Utils: Add this section before your class implementation
 */

/**
 This creates a new query parameters string from the given NSDictionary. For
 example, if the input is @{@"day":@"Tuesday", @"month":@"January"}, the output
 string will be @"day=Tuesday&month=January".
 @param queryParameters The input dictionary.
 @return The created parameters string.
*/
static NSString* NSStringFromQueryParameters(NSDictionary* queryParameters)
{
    NSMutableArray* parts = [NSMutableArray array];
    [queryParameters enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL *stop) {
        NSString *part = [NSString stringWithFormat: @"%@=%@",
            [key stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding],
            [value stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding]
        ];
        [parts addObject:part];
    }];
    return [parts componentsJoinedByString: @"&"];
}

/**
 Creates a new URL by adding the given query parameters.
 @param URL The input URL.
 @param queryParameters The query parameter dictionary to add.
 @return A new NSURL.
*/
static NSURL* NSURLByAppendingQueryParameters(NSURL* URL, NSDictionary* queryParameters)
{
    NSString* URLString = [NSString stringWithFormat:@"%@?%@",
        [URL absoluteString],
        NSStringFromQueryParameters(queryParameters)
    ];
    return [NSURL URLWithString:URLString];
}

How to create a JavaScript callback for knowing when an image is loaded?

If the goal is to style the img after browser has rendered image, you should:

const img = new Image();
img.src = 'path/to/img.jpg';

img.decode().then(() => {
/* set styles */
/* add img to DOM */ 
});

because the browser first loads the compressed version of image, then decodes it, finally paints it. since there is no event for paint you should run your logic after browser has decoded the img tag.

Insert value into a string at a certain position?

You can't modify strings; they're immutable. You can do this instead:

txtBox.Text = txtBox.Text.Substring(0, i) + "TEXT" + txtBox.Text.Substring(i);

Print a list of all installed node.js modules

list of all globally installed third party modules, write in console:

 npm -g ls

How to style a checkbox using CSS

With pure CSS, nothing fancy with :before and :after, no transforms, you can turn off the default appearance and then style it with an inline background image like the following example. This works in Chrome, Firefox, Safari, and now Edge (Chromium Edge).

_x000D_
_x000D_
INPUT[type=checkbox]:focus
{
    outline: 1px solid rgba(0, 0, 0, 0.2);
}

INPUT[type=checkbox]
{
    background-color: #DDD;
    border-radius: 2px;
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    width: 17px;
    height: 17px;
    cursor: pointer;
    position: relative;
    top: 5px;
}

INPUT[type=checkbox]:checked
{
    background-color: #409fd6;
    background: #409fd6 url("data:image/gif;base64,R0lGODlhCwAKAIABAP////3cnSH5BAEKAAEALAAAAAALAAoAAAIUjH+AC73WHIsw0UCjglraO20PNhYAOw==") 3px 3px no-repeat;
}
_x000D_
<form>
  <label><input type="checkbox"> I Agree To Terms &amp; Conditions</label>
</form>
_x000D_
_x000D_
_x000D_

How do I select and store columns greater than a number in pandas?

Sample DF:

In [79]: df = pd.DataFrame(np.random.randint(5, 15, (10, 3)), columns=list('abc'))

In [80]: df
Out[80]:
    a   b   c
0   6  11  11
1  14   7   8
2  13   5  11
3  13   7  11
4  13   5   9
5   5  11   9
6   9   8   6
7   5  11  10
8   8  10  14
9   7  14  13

present only those rows where b > 10

In [81]: df[df.b > 10]
Out[81]:
   a   b   c
0  6  11  11
5  5  11   9
7  5  11  10
9  7  14  13

Minimums (for all columns) for the rows satisfying b > 10 condition

In [82]: df[df.b > 10].min()
Out[82]:
a     5
b    11
c     9
dtype: int32

Minimum (for the b column) for the rows satisfying b > 10 condition

In [84]: df.loc[df.b > 10, 'b'].min()
Out[84]: 11

UPDATE: starting from Pandas 0.20.1 the .ix indexer is deprecated, in favor of the more strict .iloc and .loc indexers.

What is "String args[]"? parameter in main method Java

try this:

System.getProperties().getProperty("sun.java.command", 
    System.getProperties().getProperty("sun.rt.javaCommand"));

How to: Add/Remove Class on mouseOver/mouseOut - JQuery .hover?

You are missing the dot on the selector, and you can use toggleClass method on jquery:

$(".result").hover(
  function () {
    $(this).toggleClass("result_hover")      
  }
);

String contains - ignore case

You can use

org.apache.commons.lang3.StringUtils.containsIgnoreCase(CharSequence str,
                                     CharSequence searchStr);

Checks if CharSequence contains a search CharSequence irrespective of case, handling null. Case-insensitivity is defined as by String.equalsIgnoreCase(String).

A null CharSequence will return false.

This one will be better than regex as regex is always expensive in terms of performance.

For official doc, refer to : StringUtils.containsIgnoreCase

Update :

If you are among the ones who

  • don't want to use Apache commons library
  • don't want to go with the expensive regex/Pattern based solutions,
  • don't want to create additional string object by using toLowerCase,

you can implement your own custom containsIgnoreCase using java.lang.String.regionMatches

public boolean regionMatches(boolean ignoreCase,
                             int toffset,
                             String other,
                             int ooffset,
                             int len)

ignoreCase : if true, ignores case when comparing characters.

public static boolean containsIgnoreCase(String str, String searchStr)     {
    if(str == null || searchStr == null) return false;

    final int length = searchStr.length();
    if (length == 0)
        return true;

    for (int i = str.length() - length; i >= 0; i--) {
        if (str.regionMatches(true, i, searchStr, 0, length))
            return true;
    }
    return false;
}

Multiple submit buttons in an HTML form

You can do it with CSS.

Put the buttons in the markup with the Next button first, then the Prev button afterwards.

Then use CSS to position them to appear the way you want.

Angular 2 / 4 / 5 - Set base href dynamically

Frankly speaking, your case works fine for me!

I'm using Angular 5.

<script type='text/javascript'>
    var base = window.location.href.substring(0, window.location.href.toLowerCase().indexOf('index.aspx'))
    document.write('<base href="' + base + '" />');
</script>

How to properly use the "choices" field option in Django

The cleanest solution is to use the django-model-utils library:

from model_utils import Choices

class Article(models.Model):
    STATUS = Choices('draft', 'published')
    status = models.CharField(choices=STATUS, default=STATUS.draft, max_length=20)

https://django-model-utils.readthedocs.io/en/latest/utilities.html#choices

Unit test naming best practices

Class Names. For test fixture names, I find that "Test" is quite common in the ubiquitous language of many domains. For example, in an engineering domain: StressTest, and in a cosmetics domain: SkinTest. Sorry to disagree with Kent, but using "Test" in my test fixtures (StressTestTest?) is confusing.

"Unit" is also used a lot in domains. E.g. MeasurementUnit. Is a class called MeasurementUnitTest a test of "Measurement" or "MeasurementUnit"?

Therefore I like to use the "Qa" prefix for all my test classes. E.g. QaSkinTest and QaMeasurementUnit. It is never confused with domain objects, and using a prefix rather than a suffix means that all the test fixtures live together visually (useful if you have fakes or other support classes in your test project)

Namespaces. I work in C# and I keep my test classes in the same namespace as the class they are testing. It is more convenient than having separate test namespaces. Of course, the test classes are in a different project.

Test method names. I like to name my methods WhenXXX_ExpectYYY. It makes the precondition clear, and helps with automated documentation (a la TestDox). This is similar to the advice on the Google testing blog, but with more separation of preconditions and expectations. For example:

WhenDivisorIsNonZero_ExpectDivisionResult
WhenDivisorIsZero_ExpectError
WhenInventoryIsBelowOrderQty_ExpectBackOrder
WhenInventoryIsAboveOrderQty_ExpectReducedInventory

Clear and refresh jQuery Chosen dropdown list

If trigger("chosen:updated"); not working, use .trigger("liszt:updated"); of @Nhan Tran it is working fine.

Datatables - Search Box outside datatable

You can use the DataTables api to filter the table. So all you need is your own input field with a keyup event that triggers the filter function to DataTables. With css or jquery you can hide/remove the existing search input field. Or maybe DataTables has a setting to remove/not-include it.

Checkout the Datatables API documentation on this.

Example:

HTML

<input type="text" id="myInputTextField">

JS

oTable = $('#myTable').DataTable();   //pay attention to capital D, which is mandatory to retrieve "api" datatables' object, as @Lionel said
$('#myInputTextField').keyup(function(){
      oTable.search($(this).val()).draw() ;
})

What are the aspect ratios for all Android phone and tablet devices?

It is safe to assume that popular handsets are WVGA800 or bigger. Although, there are a good amount of HVGA screens, they are of secondary concern.

List of android screen sizes

http://developer.android.com/guide/practices/screens_support.html

Aspect ratio calculator

http://andrew.hedges.name/experiments/aspect_ratio/

How to install Google Play Services in a Genymotion VM (with no drag and drop support)?

As of Genymotion 2.10.0 and onwards, GApps can be installed from the emulator toolbar. Please refer to answer by @MichaelStoddart.

Next follows former answer kept here for historic reason:

Genymotion doesn't provide Google Apps. To install Google Apps:

  1. Upgrade Genymotion and VirtualBox to the latest version.

  2. Download two zip files:
    - ARM Translation Installer v1.1
    - Google Apps for your Android version: 2.3.7 - 4.4.4 or 4.4 - 6.0 (with platform and variant) You can also find the GApps list in the wbroek user GitHubGist page.

  3. Open Genymotion emulator and go to home screen then drag and drop the first file Genymotion-ARM-Translation_v1.1.zip over the emulator. A dialog will appear and show as file transfer in progress, then another dialog will appear and ask that do you want to flash it on the emulator. Click OK and reboot the device by running adb reboot from your terminal or command prompt.

  4. Drag and drop the second file gapps-*-signed.zip and repeat the same steps as above. Run adb reboot again and, once rebooted, Google Apps will be in the emulator.

  5. At this point 'Google Apps Services' will crash frequently with the following message google play services has stopped working. Open Google Play. After providing your account details, open Google Play and update your installed Google Apps. This seems to make Google Play realize you have an old Google Play Services and will ask you to update (in my case, updating Google Hangouts required a new version of Google Play Services). I've also heard that simply waiting will also prompt you to update. The 'Google Play Services' app doesn't seem to appear otherwise - you can't search for it. You should then see an offer to update Google Play Services. Once the new Google Play Services is installed you will now have stable, working access to Google Play

gcc: undefined reference to

However, avpicture_get_size is defined.

No, as the header (<libavcodec/avcodec.h>) just declares it.

The definition is in the library itself.

So you might like to add the linker option to link libavcodec when invoking gcc:

-lavcodec

Please also note that libraries need to be specified on the command line after the files needing them:

gcc -I$HOME/ffmpeg/include program.c -lavcodec

Not like this:

gcc -lavcodec -I$HOME/ffmpeg/include program.c

Referring to Wyzard's comment, the complete command might look like this:

gcc -I$HOME/ffmpeg/include program.c -L$HOME/ffmpeg/lib -lavcodec

For libraries not stored in the linkers standard location the option -L specifies an additional search path to lookup libraries specified using the -l option, that is libavcodec.x.y.z in this case.


For a detailed reference on GCC's linker option, please read here.

Where does git config --global get written to?

I am running Windows 7 and using git as setup by following the instructions on GitHub (a year or two back). A rather common use-case I would have thought. None of the answers above helped me, and after much frustration I eventually found my 'real' gitconfig file in the following directory;

C:\Users\Bill\AppData\Local\GitHub\PortableGit_054f2e797ebafd44a30203088cd 3d58663c627ef\etc

Obviously substitute your user name and presumably the suffix after PortableGit_ is a unique GUID or similar.

jQuery Determine if a matched class has a given id

I would probably use $('.mydiv').is('#foo'); That said if you know the Id why wouldnt you just apply it to the selector in the first place?

How to auto adjust table td width from the content

Remove all widths set using CSS and set white-space to nowrap like so:

.content-loader tr td {
    white-space: nowrap;
}

I would also remove the fixed width from the container (or add overflow-x: scroll to the container) if you want the fields to display in their entirety without it looking odd...

See more here: http://www.w3schools.com/cssref/pr_text_white-space.asp

NSArray + remove item from array

Made a category like mxcl, but this is slightly faster.

My testing shows ~15% improvement (I could be wrong, feel free to compare the two yourself).

Basically I take the portion of the array thats in front of the object and the portion behind and combine them. Thus excluding the element.

- (NSArray *)prefix_arrayByRemovingObject:(id)object 
{
    if (!object) {
        return self;
    }

    NSUInteger indexOfObject = [self indexOfObject:object];
    NSArray *firstSubArray = [self subarrayWithRange:NSMakeRange(0, indexOfObject)];
    NSArray *secondSubArray = [self subarrayWithRange:NSMakeRange(indexOfObject + 1, self.count - indexOfObject - 1)];
    NSArray *newArray = [firstSubArray arrayByAddingObjectsFromArray:secondSubArray];

    return newArray;
}

Eloquent: find() and where() usage laravel

Not Found Exceptions

Sometimes you may wish to throw an exception if a model is not found. This is particularly useful in routes or controllers. The findOrFail and firstOrFail methods will retrieve the first result of the query. However, if no result is found, a Illuminate\Database\Eloquent\ModelNotFoundException will be thrown:

$model = App\Flight::findOrFail(1);

$model = App\Flight::where('legs', '>', 100)->firstOrFail();

If the exception is not caught, a 404 HTTP response is automatically sent back to the user. It is not necessary to write explicit checks to return 404 responses when using these methods:

Route::get('/api/flights/{id}', function ($id) {
    return App\Flight::findOrFail($id);
});

Get List of connected USB Devices

  lstResult.Clear();
  foreach (ManagementObject drive in new ManagementObjectSearcher("select * from Win32_DiskDrive where InterfaceType='USB'").Get())
  {
       foreach (ManagementObject partition in new ManagementObjectSearcher("ASSOCIATORS OF {Win32_DiskDrive.DeviceID='" + drive["DeviceID"] + "'} WHERE AssocClass = Win32_DiskDriveToDiskPartition").Get())
       {
            foreach (ManagementObject disk in new ManagementObjectSearcher("ASSOCIATORS OF {Win32_DiskPartition.DeviceID='" + partition["DeviceID"] + "'} WHERE AssocClass = Win32_LogicalDiskToPartition").Get())
            {
                  foreach (var item in disk.Properties)
                  {
                       object value = disk.GetPropertyValue(item.Name);
                  }
                  string valor = disk["Name"].ToString();
                  lstResult.Add(valor);
                  }
             }
        }
   }

JavaScript: changing the value of onclick with or without jQuery

Came up with a quick and dirty fix to this. Just used <select onchange='this.options[this.selectedIndex].onclick();> <option onclick='alert("hello world")' ></option> </select>

Hope this helps

Which HTTP methods match up to which CRUD methods?

I Was searching for the same answer, here is what IBM say. IBM Link

POST            Creates a new resource.
GET             Retrieves a resource.
PUT             Updates an existing resource.
DELETE          Deletes a resource.

How do I properly escape quotes inside HTML attributes?

Another option is replacing double quotes with single quotes if you don't mind whatever it is. But I don't mention this one:

<option value='"asd'>test</option>

I mention this one:

<option value="'asd">test</option>

In my case I used this solution.

Node Multer unexpected field

since 2 images are getting uploaded! one with file extension and other file without extension. to delete tmp_path (file without extension)

after
src.pipe(dest);

add below code

fs.unlink(tmp_path); //deleting the tmp_path

The connection to adb is down, and a severe error has occurred

I had exactly the same problem with you. And after two days wondering why this occurs to me, I finally got through this by moving the adb.exe from the unreliable software list of the COMODO anti-virus to its reliable software list. At that time, I had tried at least 5 kinds of measures to make the adb work, including all above...

Checking if a field contains a string

As of version 2.4, you can create a text index on the field(s) to search and use the $text operator for querying.

First, create the index:

db.users.createIndex( { "username": "text" } )

Then, to search:

db.users.find( { $text: { $search: "son" } } )

Benchmarks (~150K documents):

  • Regex (other answers) => 5.6-6.9 seconds
  • Text Search => .164-.201 seconds

Notes:

  • A collection can have only one text index. You can use a wildcard text index if you want to search any string field, like this: db.collection.createIndex( { "$**": "text" } ).
  • A text index can be large. It contains one index entry for each unique post-stemmed word in each indexed field for each document inserted.
  • A text index will take longer to build than a normal index.
  • A text index does not store phrases or information about the proximity of words in the documents. As a result, phrase queries will run much more effectively when the entire collection fits in RAM.

Manage toolbar's navigation and back button from fragment in android

I have head around lots of solutions and none of them works perfectly. I've used variation of solutions available in my project which is here as below. Please use this code inside class where you are initialising toolbar and drawer layout.

getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
                drawerFragment.mDrawerToggle.setDrawerIndicatorEnabled(false);
                getSupportActionBar().setDisplayHomeAsUpEnabled(true);// show back button
                toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        onBackPressed();
                    }
                });
            } else {
                //show hamburger
                drawerFragment.mDrawerToggle.setDrawerIndicatorEnabled(true);
                getSupportActionBar().setDisplayHomeAsUpEnabled(false);
                drawerFragment.mDrawerToggle.syncState();
                toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        drawerFragment.mDrawerLayout.openDrawer(GravityCompat.START);
                    }
                });
            }
        }
    });

How do you generate dynamic (parameterized) unit tests in Python?

I had trouble making these work for setUpClass.

Here's a version of Javier's answer that gives setUpClass access to dynamically allocated attributes.

import unittest


class GeneralTestCase(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        print ''
        print cls.p1
        print cls.p2

    def runTest1(self):
        self.assertTrue((self.p2 - self.p1) == 1)

    def runTest2(self):
        self.assertFalse((self.p2 - self.p1) == 2)


def load_tests(loader, tests, pattern):
    test_cases = unittest.TestSuite()
    for p1, p2 in [(1, 2), (3, 4)]:
        clsname = 'TestCase_{}_{}'.format(p1, p2)
        dct = {
            'p1': p1,
            'p2': p2,
        }
        cls = type(clsname, (GeneralTestCase,), dct)
        test_cases.addTest(cls('runTest1'))
        test_cases.addTest(cls('runTest2'))
    return test_cases

Outputs

1
2
..
3
4
..
----------------------------------------------------------------------
Ran 4 tests in 0.000s

OK

mappedBy reference an unknown target entity property

The mappedBy attribute is referencing customer while the property is mCustomer, hence the error message. So either change your mapping into:

/** The collection of stores. */
@OneToMany(mappedBy = "mCustomer", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Collection<Store> stores;

Or change the entity property into customer (which is what I would do).

The mappedBy reference indicates "Go look over on the bean property named 'customer' on the thing I have a collection of to find the configuration."

.NET Format a string with fixed spaces

Here's a VB.NET version I created, inspired by Joel Coehoorn's answer, Oliver's edit, and shaunmartin's comment:

    <Extension()>
Public Function PadCenter(ByVal [string] As String, ByVal width As Integer, ByVal c As Char) As String

    If [string] Is Nothing Then [string] = String.Empty
    If (width <= [string].Length) Then Return [string]

    Dim padding = width - [string].Length
    Return [string].PadLeft([string].Length + (padding \ 2), c).PadRight(width, c)

End Function

<Extension()>
Public Function PadCenter(ByVal [string] As String, ByVal width As Integer) As String

    If [string] Is Nothing Then [string] = String.Empty
    If (width <= [string].Length) Then Return [string]

    Dim padding = width - [string].Length
    Return [string].PadLeft([string].Length + (padding \ 2)).PadRight(width)

End Function

This is set up as a string extension, inside a Public Module (the way you do Extensions in VB.NET, a bit different than C#). My slight change is that it treats a null string as an empty string, and it pads an empty string with the width value (meets my particular needs). Hopefully this will convert easily to C# for anyone who needs it. If there's a better way to reference the answers, edits, and comments I mentioned above, which inspired my post, please let me know and I'll do it - I'm relatively new to posting, and I couldn't figure out to leave a comment (might not have enough rep yet).

How to list the size of each file and directory and sort by descending size in Bash?

Apparently --max-depth option is not in Mac OS X's version of the du command. You can use the following instead.

du -h -d 1 | sort -n

Proper way to renew distribution certificate for iOS

When your certificate expires, it simply disappears from the ‘Certificates, Identifier & Profiles’ section of Member Center. There is no ‘Renew’ button that allows you to renew your certificate. You can revoke a certificate and generate a new one before it expires. Or you can wait for it to expire and disappear, then generate a new certificate. In Apple's App Distribution Guide:

Replacing Expired Certificates

When your development or distribution certificate expires, remove it and request a new certificate in Xcode.

When your certificate expires or is revoked, any provisioning profile that made use of the expired/revoked certificate will be reflected as ‘Invalid’. You cannot build and sign any app using these invalid provisioning profiles. As you can imagine, I'd rather revoke and regenerate a certificate before it expires.

Q: If I do that then will all my live apps be taken down?

Apps that are already on the App Store continue to function fine. Again, in Apple's App Distribution Guide:

Important: Re-creating your development or distribution certificates doesn’t affect apps that you’ve submitted to the store nor does it affect your ability to update them.

So…

Q: How to I properly renew it?

As mentioned above, there is no renewing of certificates. Follow the steps below to revoke and regenerate a new certificate, along with the affected provisioning profiles. The instructions have been updated for Xcode 8.3 and Xcode 9.

Step 1: Revoke the expiring certificate

Login to Member Center > Certificates, Identifiers & Profiles, select the expiring certificate. Take note of the expiry date of the certificate, and click the ‘Revoke’ button.

Select the expiring certificate and click the Revoke button

Step 2: (Optional) Remove the revoked certificate from your Keychain

Optionally, if you don't want to have the revoked certificate lying around in your system, you can delete them from your system. Unfortunately, the ‘Delete Certificate’ function in Xcode > Preferences > Accounts > [Apple ID] > Manage Certificates… seems to be always disabled, so we have to delete them manually using Keychain Access.app (/Applications/Utilities/Keychain Access.app).

Optionally remove the revoked certificate using Keychain Access.app

Filter by ‘login’ Keychains and ‘Certificates’ Category. Locate the certificate that you've just revoked in Step 1.

Depending on the certificate that you've just revoked, search for either ‘Mac’ or ‘iPhone’. Mac App Store distribution certificates begin with “3rd Party Mac Developer”, and iOS App Store distribution certificates begin with “iPhone Distribution”.

You can locate the revoked certificate based on the team name, the type of certificate (Mac or iOS) and the expiry date of the certificate you've noted down in Step 1.

Step 3: Request a new certificate using Xcode

Under Xcode > Preferences > Accounts > [Apple ID] > Manage Certificates…, click on the ‘+’ button on the lower left, and select the same type of certificate that you've just revoked to let Xcode request a new one for you.

Let Xcode request a new certificate for you in Xcode > Preferences > Accounts > Apple ID > Manage Certificates…

Step 4: Update your provisioning profiles to use the new certificate

After which, head back to Member Center > Certificates, Identifiers & Profiles > Provisioning Profiles > All. You'll notice that any provisioning profile that made use of the revoked certificate is now reflected as ‘Invalid’.

Notice that any provisioning profile that made use of the revoked certificate is now reflected as ‘Invalid’

Click on any profile that are now ‘Invalid’, click ‘Edit’, then choose the newly created certificate, then click on ‘Generate’. Repeat this until all provisioning profiles are regenerated with the new certificate.

Choose the newly created certificate, and click on Generate

Step 5: Use Xcode to download the new provisioning profiles

Tip: Before you download the new profiles using Xcode, you may want to clear any existing and possibly invalid provisioning profiles from your Mac. You can do so by removing all the profiles from ~/Library/MobileDevice/Provisioning Profiles

Back in Xcode > Preferences > Accounts > [Apple ID], click on the ‘Download All Profiles’ button to ask Xcode to download all the provisioning profiles from your developer account.

Click Download All Profiles for Xcode to download all the newly generated profiles

EPPlus - Read Excel Table

I have got an error on the first answer so I have changed some code line.

Please try my new code, it's working for me.

using OfficeOpenXml;
using OfficeOpenXml.Table;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

public static class ImportExcelReader
{
    public static List<T> ImportExcelToList<T>(this ExcelWorksheet worksheet) where T : new()
    {
        //DateTime Conversion
        Func<double, DateTime> convertDateTime = new Func<double, DateTime>(excelDate =>
        {
            if (excelDate < 1)
            {
                throw new ArgumentException("Excel dates cannot be smaller than 0.");
            }

            DateTime dateOfReference = new DateTime(1900, 1, 1);

            if (excelDate > 60d)
            {
                excelDate = excelDate - 2;
            }
            else
            {
                excelDate = excelDate - 1;
            }

            return dateOfReference.AddDays(excelDate);
        });

        ExcelTable table = null;

        if (worksheet.Tables.Any())
        {
            table = worksheet.Tables.FirstOrDefault();
        }
        else
        {
            table = worksheet.Tables.Add(worksheet.Dimension, "tbl" + ShortGuid.NewGuid().ToString());

            ExcelAddressBase newaddy = new ExcelAddressBase(table.Address.Start.Row, table.Address.Start.Column, table.Address.End.Row + 1, table.Address.End.Column);

            //Edit the raw XML by searching for all references to the old address
            table.TableXml.InnerXml = table.TableXml.InnerXml.Replace(table.Address.ToString(), newaddy.ToString());
        }

        //Get the cells based on the table address
        List<IGrouping<int, ExcelRangeBase>> groups = table.WorkSheet.Cells[table.Address.Start.Row, table.Address.Start.Column, table.Address.End.Row, table.Address.End.Column]
            .GroupBy(cell => cell.Start.Row)
            .ToList();

        //Assume the second row represents column data types (big assumption!)
        List<Type> types = groups.Skip(1).FirstOrDefault().Select(rcell => rcell.Value.GetType()).ToList();

        //Get the properties of T
        List<PropertyInfo> modelProperties = new T().GetType().GetProperties().ToList();

        //Assume first row has the column names
        var colnames = groups.FirstOrDefault()
            .Select((hcell, idx) => new
            {
                Name = hcell.Value.ToString(),
                index = idx
            })
            .Where(o => modelProperties.Select(p => p.Name).Contains(o.Name))
            .ToList();

        //Everything after the header is data
        List<List<object>> rowvalues = groups
            .Skip(1) //Exclude header
            .Select(cg => cg.Select(c => c.Value).ToList()).ToList();

        //Create the collection container
        List<T> collection = new List<T>();
        foreach (List<object> row in rowvalues)
        {
            T tnew = new T();
            foreach (var colname in colnames)
            {
                //This is the real wrinkle to using reflection - Excel stores all numbers as double including int
                object val = row[colname.index];
                Type type = types[colname.index];
                PropertyInfo prop = modelProperties.FirstOrDefault(p => p.Name == colname.Name);

                //If it is numeric it is a double since that is how excel stores all numbers
                if (type == typeof(double))
                {
                    //Unbox it
                    double unboxedVal = (double)val;

                    //FAR FROM A COMPLETE LIST!!!
                    if (prop.PropertyType == typeof(int))
                    {
                        prop.SetValue(tnew, (int)unboxedVal);
                    }
                    else if (prop.PropertyType == typeof(double))
                    {
                        prop.SetValue(tnew, unboxedVal);
                    }
                    else if (prop.PropertyType == typeof(DateTime))
                    {
                        prop.SetValue(tnew, convertDateTime(unboxedVal));
                    }
                    else if (prop.PropertyType == typeof(string))
                    {
                        prop.SetValue(tnew, val.ToString());
                    }
                    else
                    {
                        throw new NotImplementedException(string.Format("Type '{0}' not implemented yet!", prop.PropertyType.Name));
                    }
                }
                else
                {
                    //Its a string
                    prop.SetValue(tnew, val);
                }
            }
            collection.Add(tnew);
        }

        return collection;
    }
}

How to call this function? please view below code;

private List<FundraiserStudentListModel> GetStudentsFromExcel(HttpPostedFileBase file)
    {
        List<FundraiserStudentListModel> list = new List<FundraiserStudentListModel>();
        if (file != null)
        {
            try
            {
                using (ExcelPackage package = new ExcelPackage(file.InputStream))
                {
                    ExcelWorkbook workbook = package.Workbook;
                    if (workbook != null)
                    {
                        ExcelWorksheet worksheet = workbook.Worksheets.FirstOrDefault();
                        if (worksheet != null)
                        {
                            list = worksheet.ImportExcelToList<FundraiserStudentListModel>();
                        }
                    }
                }
            }
            catch (Exception err)
            {
                //save error log
            }
        }
        return list;
    }

FundraiserStudentListModel here:

 public class FundraiserStudentListModel
{
    public string Name { get; set; }
    public string Email { get; set; }
    public string Phone { get; set; }
}

How do I convert a float number to a whole number in JavaScript?

There are many suggestions here. The bitwise OR seems to be the simplest by far. Here is another short solution which works with negative numbers as well using the modulo operator. It is probably easier to understand than the bitwise OR:

intval = floatval - floatval%1;

This method also works with high value numbers where neither '|0' nor '~~' nor '>>0' work correctly:

> n=4294967295;
> n|0
-1
> ~~n
-1
> n>>0
-1
> n-n%1
4294967295

What exactly does big ? notation represent?

First let's understand what big O, big Theta and big Omega are. They are all sets of functions.

Big O is giving upper asymptotic bound, while big Omega is giving a lower bound. Big Theta gives both.

Everything that is ?(f(n)) is also O(f(n)), but not the other way around.
T(n) is said to be in ?(f(n)) if it is both in O(f(n)) and in Omega(f(n)).
In sets terminology, ?(f(n)) is the intersection of O(f(n)) and Omega(f(n))

For example, merge sort worst case is both O(n*log(n)) and Omega(n*log(n)) - and thus is also ?(n*log(n)), but it is also O(n^2), since n^2 is asymptotically "bigger" than it. However, it is not ?(n^2), Since the algorithm is not Omega(n^2).

A bit deeper mathematic explanation

O(n) is asymptotic upper bound. If T(n) is O(f(n)), it means that from a certain n0, there is a constant C such that T(n) <= C * f(n). On the other hand, big-Omega says there is a constant C2 such that T(n) >= C2 * f(n))).

Do not confuse!

Not to be confused with worst, best and average cases analysis: all three (Omega, O, Theta) notation are not related to the best, worst and average cases analysis of algorithms. Each one of these can be applied to each analysis.

We usually use it to analyze complexity of algorithms (like the merge sort example above). When we say "Algorithm A is O(f(n))", what we really mean is "The algorithms complexity under the worst1 case analysis is O(f(n))" - meaning - it scales "similar" (or formally, not worse than) the function f(n).

Why we care for the asymptotic bound of an algorithm?

Well, there are many reasons for it, but I believe the most important of them are:

  1. It is much harder to determine the exact complexity function, thus we "compromise" on the big-O/big-Theta notations, which are informative enough theoretically.
  2. The exact number of ops is also platform dependent. For example, if we have a vector (list) of 16 numbers. How much ops will it take? The answer is: it depends. Some CPUs allow vector additions, while other don't, so the answer varies between different implementations and different machines, which is an undesired property. The big-O notation however is much more constant between machines and implementations.

To demonstrate this issue, have a look at the following graphs: enter image description here

It is clear that f(n) = 2*n is "worse" than f(n) = n. But the difference is not quite as drastic as it is from the other function. We can see that f(n)=logn quickly getting much lower than the other functions, and f(n) = n^2 is quickly getting much higher than the others.
So - because of the reasons above, we "ignore" the constant factors (2* in the graphs example), and take only the big-O notation.

In the above example, f(n)=n, f(n)=2*n will both be in O(n) and in Omega(n) - and thus will also be in Theta(n).
On the other hand - f(n)=logn will be in O(n) (it is "better" than f(n)=n), but will NOT be in Omega(n) - and thus will also NOT be in Theta(n).
Symetrically, f(n)=n^2 will be in Omega(n), but NOT in O(n), and thus - is also NOT Theta(n).


1Usually, though not always. when the analysis class (worst, average and best) is missing, we really mean the worst case.

How to limit the number of selected checkboxes?

I did this today, the difference being I wanted to uncheck the oldest checkbox instead of stopping the user from checking a new one:

    let maxCheckedArray = [];
    let assessmentOptions = jQuery('.checkbox-fields').find('input[type="checkbox"]');
    assessmentOptions.on('change', function() {
        let checked = jQuery(this).prop('checked');
        if(checked) {
            maxCheckedArray.push(jQuery(this));
        }
        if(maxCheckedArray.length >= 3) {
            let old_item = maxCheckedArray.shift();
            old_item.prop('checked', false);
        }
    });

How to print the data in byte array as characters?

Try it:

public static String print(byte[] bytes) {
    StringBuilder sb = new StringBuilder();
    sb.append("[ ");
    for (byte b : bytes) {
        sb.append(String.format("0x%02X ", b));
    }
    sb.append("]");
    return sb.toString();
}

Example:

 public static void main(String []args){
    byte[] bytes = new byte[] { 
        (byte) 0x01, (byte) 0xFF, (byte) 0x2E, (byte) 0x6E, (byte) 0x30
    };

    System.out.println("bytes = " + print(bytes));
 }

Output: bytes = [ 0x01 0xFF 0x2E 0x6E 0x30 ]

Shared-memory objects in multiprocessing

I run into the same problem and wrote a little shared-memory utility class to work around it.

I'm using multiprocessing.RawArray (lockfree), and also the access to the arrays is not synchronized at all (lockfree), be careful not to shoot your own feet.

With the solution I get speedups by a factor of approx 3 on a quad-core i7.

Here's the code: Feel free to use and improve it, and please report back any bugs.

'''
Created on 14.05.2013

@author: martin
'''

import multiprocessing
import ctypes
import numpy as np

class SharedNumpyMemManagerError(Exception):
    pass

'''
Singleton Pattern
'''
class SharedNumpyMemManager:    

    _initSize = 1024

    _instance = None

    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super(SharedNumpyMemManager, cls).__new__(
                                cls, *args, **kwargs)
        return cls._instance        

    def __init__(self):
        self.lock = multiprocessing.Lock()
        self.cur = 0
        self.cnt = 0
        self.shared_arrays = [None] * SharedNumpyMemManager._initSize

    def __createArray(self, dimensions, ctype=ctypes.c_double):

        self.lock.acquire()

        # double size if necessary
        if (self.cnt >= len(self.shared_arrays)):
            self.shared_arrays = self.shared_arrays + [None] * len(self.shared_arrays)

        # next handle
        self.__getNextFreeHdl()        

        # create array in shared memory segment
        shared_array_base = multiprocessing.RawArray(ctype, np.prod(dimensions))

        # convert to numpy array vie ctypeslib
        self.shared_arrays[self.cur] = np.ctypeslib.as_array(shared_array_base)

        # do a reshape for correct dimensions            
        # Returns a masked array containing the same data, but with a new shape.
        # The result is a view on the original array
        self.shared_arrays[self.cur] = self.shared_arrays[self.cnt].reshape(dimensions)

        # update cnt
        self.cnt += 1

        self.lock.release()

        # return handle to the shared memory numpy array
        return self.cur

    def __getNextFreeHdl(self):
        orgCur = self.cur
        while self.shared_arrays[self.cur] is not None:
            self.cur = (self.cur + 1) % len(self.shared_arrays)
            if orgCur == self.cur:
                raise SharedNumpyMemManagerError('Max Number of Shared Numpy Arrays Exceeded!')

    def __freeArray(self, hdl):
        self.lock.acquire()
        # set reference to None
        if self.shared_arrays[hdl] is not None: # consider multiple calls to free
            self.shared_arrays[hdl] = None
            self.cnt -= 1
        self.lock.release()

    def __getArray(self, i):
        return self.shared_arrays[i]

    @staticmethod
    def getInstance():
        if not SharedNumpyMemManager._instance:
            SharedNumpyMemManager._instance = SharedNumpyMemManager()
        return SharedNumpyMemManager._instance

    @staticmethod
    def createArray(*args, **kwargs):
        return SharedNumpyMemManager.getInstance().__createArray(*args, **kwargs)

    @staticmethod
    def getArray(*args, **kwargs):
        return SharedNumpyMemManager.getInstance().__getArray(*args, **kwargs)

    @staticmethod    
    def freeArray(*args, **kwargs):
        return SharedNumpyMemManager.getInstance().__freeArray(*args, **kwargs)

# Init Singleton on module load
SharedNumpyMemManager.getInstance()

if __name__ == '__main__':

    import timeit

    N_PROC = 8
    INNER_LOOP = 10000
    N = 1000

    def propagate(t):
        i, shm_hdl, evidence = t
        a = SharedNumpyMemManager.getArray(shm_hdl)
        for j in range(INNER_LOOP):
            a[i] = i

    class Parallel_Dummy_PF:

        def __init__(self, N):
            self.N = N
            self.arrayHdl = SharedNumpyMemManager.createArray(self.N, ctype=ctypes.c_double)            
            self.pool = multiprocessing.Pool(processes=N_PROC)

        def update_par(self, evidence):
            self.pool.map(propagate, zip(range(self.N), [self.arrayHdl] * self.N, [evidence] * self.N))

        def update_seq(self, evidence):
            for i in range(self.N):
                propagate((i, self.arrayHdl, evidence))

        def getArray(self):
            return SharedNumpyMemManager.getArray(self.arrayHdl)

    def parallelExec():
        pf = Parallel_Dummy_PF(N)
        print(pf.getArray())
        pf.update_par(5)
        print(pf.getArray())

    def sequentialExec():
        pf = Parallel_Dummy_PF(N)
        print(pf.getArray())
        pf.update_seq(5)
        print(pf.getArray())

    t1 = timeit.Timer("sequentialExec()", "from __main__ import sequentialExec")
    t2 = timeit.Timer("parallelExec()", "from __main__ import parallelExec")

    print("Sequential: ", t1.timeit(number=1))    
    print("Parallel: ", t2.timeit(number=1))

How to use the read command in Bash?

Typical usage might look like:

i=0
echo -e "hello1\nhello2\nhello3" | while read str ; do
    echo "$((++i)): $str"
done

and output

1: hello1
2: hello2
3: hello3

shell-script headers (#!/bin/sh vs #!/bin/csh)

This is known as a Shebang:

http://en.wikipedia.org/wiki/Shebang_(Unix)

#!interpreter [optional-arg]

A shebang is only relevant when a script has the execute permission (e.g. chmod u+x script.sh).

When a shell executes the script it will use the specified interpreter.

Example:

#!/bin/bash
# file: foo.sh
echo 1

$ chmod u+x foo.sh
$ ./foo.sh
  1

How can I scale an image in a CSS sprite

When you use sprites, you are limited to the dimensions of the image in the sprite. The background-size CSS property, mentioned by Stephen, isn't widely supported yet and might cause problems with browsers like IE8 and below - and given their market share, this isn't a viable option.

Another way to solve the problem is to use two elements and scale the sprite by using it with an img tag, like this:

<div class="sprite-image"
     style="width:20px; height:20px; overflow:hidden; position:relative">
    <!-- set width/height proportionally, to scale the sprite image -->
    <img src="sprite.png" alt="icon"
         width="20" height="80"
         style="position:absolute; top: -20px; left: 0;" />
</div>

This way, the outer element (div.sprite-image) is cropping a 20x20px image from the img tag, which acts like a scaled background-image.

Browser Timeouts

It's browser dependent. "By default, Internet Explorer has a KeepAliveTimeout value of one minute and an additional limiting factor (ServerInfoTimeout) of two minutes. Either setting can cause Internet Explorer to reset the socket." - from IE support http://support.microsoft.com/kb/813827

Firefox is around the same value I think as well.

Usually though server timeout are set lower than browser timeouts, but at least you can control that and set it higher.

You'd rather handle the timeout though, so that way you can act upon such an event. See this thread: How to detect timeout on an AJAX (XmlHttpRequest) call in the browser?

Exception: "URI formats are not supported"

I solved the same error with the Path.Combine(MapPath()) to get the physical file path instead of the http:/// www one.

How to use if statements in LESS

LESS has guard expressions for mixins, not individual attributes.

So you'd create a mixin like this:

.debug(@debug) when (@debug = true) {
    header {
      background-color: yellow;
      #title {
          background-color: orange;
      }
    }

    article {
      background-color: red;
    }
}

And turn it on or off by calling .debug(true); or .debug(false) (or not calling it at all).

How can I count the numbers of rows that a MySQL query returned?

In the event you have to solve the problem with simple SQL you might use an inline view.

select count(*) from (select * from foo) as x;

C++ Remove new line from multiline string

 std::string some_str = SOME_VAL;
 if ( some_str.size() > 0 && some_str[some_str.length()-1] == '\n' ) 
  some_str.resize( some_str.length()-1 );

or (removes several newlines at the end)

some_str.resize( some_str.find_last_not_of(L"\n")+1 );

Proper way to declare custom exceptions in modern Python?

As of Python 3.8 (2018, https://docs.python.org/dev/whatsnew/3.8.html), the recommended method is still:

class CustomExceptionName(Exception):
    """Exception raised when very uncommon things happen"""
    pass

Please don't forget to document, why a custom exception is neccessary!

If you need to, this is the way to go for exceptions with more data:

class CustomExceptionName(Exception):
    """Still an exception raised when uncommon things happen"""
    def __init__(self, message, payload=None):
        self.message = message
        self.payload = payload # you could add more args
    def __str__(self):
        return str(self.message) # __str__() obviously expects a string to be returned, so make sure not to send any other data types

and fetch them like:

try:
    raise CustomExceptionName("Very bad mistake.", "Forgot upgrading from Python 1")
except CustomExceptionName as error:
    print(str(error)) # Very bad mistake
    print("Detail: {}".format(error.payload)) # Detail: Forgot upgrading from Python 1

payload=None is important to make it pickle-able. Before dumping it, you have to call error.__reduce__(). Loading will work as expected.

You maybe should investigate in finding a solution using pythons return statement if you need much data to be transferred to some outer structure. This seems to be clearer/more pythonic to me. Advanced exceptions are heavily used in Java, which can sometimes be annoying, when using a framework and having to catch all possible errors.

grep using a character vector with multiple patterns

Not sure whether this answer has already appeared...

For the particular pattern in the question, you can just do it with a single grep() call,

grep("A[169]", myfile$Letter)

Converting a date in MySQL from string field

SELECT STR_TO_DATE(dateString, '%d/%m/%y') FROM yourTable...

NUnit Unit tests not showing in Test Explorer with Test Adapter installed

Check whether you have stated [TestFixureSetUp] and [Test]

in the test class

sample:

namespace ClassLibrary1
{
   public class SimpleCalculator
   {
      public Calculator _calculator;
      [TestFixtureSetUp]
      public void initialize()
      {
         _calculator = new Calculator();
      }
      [Test]
      public void DivideTest()
      {
         int a = 10;
         int b = 2;
         int expectedValue = a/b;
         int actualValue = _calculator.Divide(a, b);
         Assert.AreEqual(expectedValue, actualValue, "Functionality not working properly!");
      }
   }   
}

Attach Authorization header for all axios requests

Sometimes you get a case where some of the requests made with axios are pointed to endpoints that do not accept authorization headers. Thus, alternative way to set authorization header only on allowed domain is as in the example below. Place the following function in any file that gets executed each time React application runs such as in routes file.

export default () => {
    axios.interceptors.request.use(function (requestConfig) {
        if (requestConfig.url.indexOf(<ALLOWED_DOMAIN>) > -1) {
            const token = localStorage.token;
            requestConfig.headers['Authorization'] = `Bearer ${token}`;
        }

        return requestConfig;
    }, function (error) {
        return Promise.reject(error);
    });

}

jackson deserialization json to java-objects

 JsonNode node = mapper.readValue("[{\"id\":\"value11\",\"name\": \"value12\",\"qty\":\"value13\"},"

 System.out.println("id : "+node.findValues("id").get(0).asText());

this also done the trick.

How can I get System variable value in Java?

Google says to check out getenv():

Returns an unmodifiable string map view of the current system environment.

I'm not sure how system variables differ from environment variables, however, so if you could clarify I could help out more.

How to design RESTful search/filtering?

The best way to implement a RESTful search is to consider the search itself to be a resource. Then you can use the POST verb because you are creating a search. You do not have to literally create something in a database in order to use a POST.

For example:

Accept: application/json
Content-Type: application/json
POST http://example.com/people/searches
{
  "terms": {
    "ssn": "123456789"
  },
  "order": { ... },
  ...
}

You are creating a search from the user's standpoint. The implementation details of this are irrelevant. Some RESTful APIs may not even need persistence. That is an implementation detail.

Stash just a single file

Just in case you actually mean 'discard changes' whenever you use 'git stash' (and don't really use git stash to stash it temporarily), in that case you can use

git checkout -- <file>

Note that git stash is just a quicker and simple alternative to branching and doing stuff.

Is there a "between" function in C#?

So far, it looks like none of the answers have considered the likely possibility that dynamically, you don't know which value is the lower and upper bound. For the general case, you could create your own IsBetween method that would probably go something like:

    public bool IsBetween(double testValue, double bound1, double bound2)
    {
        return (testValue >= Math.Min(bound1,bound2) && testValue <= Math.Max(bound1,bound2));
    }

Simple way to copy or clone a DataRow?

But to make sure that your new row is accessible in the new table, you need to close the table:

DataTable destination = new DataTable(source.TableName);
destination = source.Clone();
DataRow sourceRow = source.Rows[0];
destination.ImportRow(sourceRow);

AngularJS resource promise

If you want to use asynchronous method you need to use callback function by $promise, here is example:

var Regions = $resource('mocks/regions.json');

$scope.regions = Regions.query();
$scope.regions.$promise.then(function (result) {
    $scope.regions = result;
});

Dynamically add properties to a existing object

Take a look at the Clay library:

http://clay.codeplex.com/

It provides something similar to the ExpandoObject but with a bunch of extra features. Here is blog post explaining how to use it:

http://weblogs.asp.net/bleroy/archive/2010/08/18/clay-malleable-c-dynamic-objects-part-2.aspx

(be sure to read the IPerson interface example)

Use string contains function in oracle SQL query

By lines I assume you mean rows in the table person. What you're looking for is:

select p.name
from   person p
where  p.name LIKE '%A%'; --contains the character 'A'

The above is case sensitive. For a case insensitive search, you can do:

select p.name
from   person p
where  UPPER(p.name) LIKE '%A%'; --contains the character 'A' or 'a'

For the special character, you can do:

select p.name
from   person p
where  p.name LIKE '%'||chr(8211)||'%'; --contains the character chr(8211)

The LIKE operator matches a pattern. The syntax of this command is described in detail in the Oracle documentation. You will mostly use the % sign as it means match zero or more characters.

Decimal to Hexadecimal Converter in Java

Here's mine

public static String dec2Hex(int num)
{
    String hex = "";

    while (num != 0)
    {
        if (num % 16 < 10)
            hex = Integer.toString(num % 16) + hex;
        else
            hex = (char)((num % 16)+55) + hex;
        num = num / 16;
    }

    return hex;
}

Target Unreachable, identifier resolved to null in JSF 2.2

I solved this problem.

My Java version was the 1.6 and I found that was using 1.7 with CDI however after that I changed the Java version to 1.7 and import the package javax.faces.bean.ManagedBean and everything worked.

Thanks @PM77-1


SOAP or REST for Web Services?

1.From my experience. I would say REST gives you option to access the URL which is already built. eg-> a word search in google. That URL could be used as webservice for REST. In SOAP, you can create your own web service and access it through SOAP client.

  1. REST supports text,JSON,XML format. Hence more versatile for communicating between two applications. While SOAP supports only XML format for message communication.

Simple way to query connected USB devices info in Python?

If you are working on windows, you can use pywin32 (old link: see update below).

I found an example here:

import win32com.client

wmi = win32com.client.GetObject ("winmgmts:")
for usb in wmi.InstancesOf ("Win32_USBHub"):
    print usb.DeviceID

Update Apr 2020:

'pywin32' release versions from 218 and up can be found here at github. Current version 227.

Illegal Character when trying to compile java code

In Android Studio

1. Menu -> Edit -> Select All
2. Menu -> Edit -> Copy
  1. Open new Notepad.exe

In Notepad

4. Menu -> Edit -> Paste
5. Menu -> Edit -> Select All
6. Menu -> Edit -> Copy 

Back In Android Studio

7. Menu -> Edit -> Paste

Absolute position of an element on the screen using jQuery

See .offset() here in the jQuery doc. It gives the position relative to the document, not to the parent. You perhaps have .offset() and .position() confused. If you want the position in the window instead of the position in the document, you can subtract off the .scrollTop() and .scrollLeft() values to account for the scrolled position.

Here's an excerpt from the doc:

The .offset() method allows us to retrieve the current position of an element relative to the document. Contrast this with .position(), which retrieves the current position relative to the offset parent. When positioning a new element on top of an existing one for global manipulation (in particular, for implementing drag-and-drop), .offset() is the more useful.

To combine these:

var offset = $("selector").offset();
var posY = offset.top - $(window).scrollTop();
var posX = offset.left - $(window).scrollLeft(); 

You can try it here (scroll to see the numbers change): http://jsfiddle.net/jfriend00/hxRPQ/

What does "TypeError 'xxx' object is not callable" means?

The other answers detail the reason for the error. A possible cause (to check) may be your class has a variable and method with the same name, which you then call. Python accesses the variable as a callable - with ().

e.g. Class A defines self.a and self.a():

>>> class A:
...     def __init__(self, val):
...         self.a = val
...     def a(self):
...         return self.a
...
>>> my_a = A(12)
>>> val = my_a.a()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable
>>>

Doctrine - How to print out the real sql, not just the prepared statement?

There is no other real query, this is how prepared statements work. The values are bound in the database server, not in the application layer.

See my answer to this question: In PHP with PDO, how to check the final SQL parametrized query?

(Repeated here for convenience:)

Using prepared statements with parametrised values is not simply another way to dynamically create a string of SQL. You create a prepared statement at the database, and then send the parameter values alone.

So what is probably sent to the database will be a PREPARE ..., then SET ... and finally EXECUTE ....

You won't be able to get some SQL string like SELECT * FROM ..., even if it would produce equivalent results, because no such query was ever actually sent to the database.

What does it mean when a PostgreSQL process is "idle in transaction"?

As mentioned here: Re: BUG #4243: Idle in transaction it is probably best to check your pg_locks table to see what is being locked and that might give you a better clue where the problem lies.

How do I efficiently iterate over each entry in a Java Map?

package com.test;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class Test {

    public static void main(String[] args) {
        Map<String, String> map = new HashMap<String, String>();
        map.put("ram", "ayodhya");
        map.put("krishan", "mathura");
        map.put("shiv", "kailash");

        System.out.println("********* Keys *********");
        Set<String> keys = map.keySet();
        for (String key : keys) {
            System.out.println(key);
        }

        System.out.println("********* Values *********");
        Collection<String> values = map.values();
        for (String value : values) {
            System.out.println(value);
        }

        System.out.println("***** Keys and Values (Using for each loop) *****");
        for (Map.Entry<String, String> entry : map.entrySet()) {
            System.out.println("Key: " + entry.getKey() + "\t Value: "
                    + entry.getValue());
        }

        System.out.println("***** Keys and Values (Using while loop) *****");
        Iterator<Entry<String, String>> entries = map.entrySet().iterator();
        while (entries.hasNext()) {
            Map.Entry<String, String> entry = (Map.Entry<String, String>) entries
                    .next();
            System.out.println("Key: " + entry.getKey() + "\t Value: "
                    + entry.getValue());
        }

        System.out
                .println("** Keys and Values (Using java 8 using lambdas )***");
        map.forEach((k, v) -> System.out
                .println("Key: " + k + "\t value: " + v));
    }
}

What is an OS kernel ? How does it differ from an operating system?

The kernel might be the operating system or it might be a part of the operating system. In Linux, the kernel is loaded and executed first. Then it starts up other bits of the OS (like init) to make the system useful.

This is especially true in a micro-kernel environment. The kernel has minimal functionality. Everything else, like file systems and TCP/IP, run as a user process.

Accessing a property in a parent Component

You could:

  • Define a userStatus parameter for the child component and provide the value when using this component from the parent:

    @Component({
      (...)
    })
    export class Profile implements OnInit {
      @Input()
      userStatus:UserStatus;
    
      (...)
    }
    

    and in the parent:

    <profile [userStatus]="userStatus"></profile>
    
  • Inject the parent into the child component:

    @Component({
      (...)
    })
    export class Profile implements OnInit {
      constructor(app:App) {
        this.userStatus = app.userStatus;
      }
    
      (...)
    }
    

    Be careful about cyclic dependencies between them.

How to script FTP upload and download?

I know this is an old question, but I wanted to add something to the answers already here in hopes of helping someone else.

You can script the ftp command with the -s:filename option. The syntax is just a list of commands to pass to the ftp shell, each terminated by a newline. This page has a nice reference to the commands that can be performed with ftp.

Upload/Download Entire Directory Structure

Using the normal ftp doesn't work very well when you need to have an entire directory tree copied to or from a ftp site. So you could use something like these to handle those situations.

These scripts works with the Windows ftp command and allows for uploading and downloading of entire directories from a single command. This makes it pretty self reliant when using on different systems.

Basically what they do is map out the directory structure to be up/downloaded, dump corresponding ftp commands to a file, then execute those commands when the mapping has finished.

ftpupload.bat

@echo off

SET FTPADDRESS=%1
SET FTPUSERNAME=%2
SET FTPPASSWORD=%3
SET LOCALDIR=%~f4
SET REMOTEDIR=%5

if "%FTPADDRESS%" == "" goto FTP_UPLOAD_USAGE
if "%FTPUSERNAME%" == "" goto FTP_UPLOAD_USAGE
if "%FTPPASSWORD%" == "" goto FTP_UPLOAD_USAGE
if "%LOCALDIR%" == "" goto FTP_UPLOAD_USAGE
if "%REMOTEDIR%" == "" goto FTP_UPLOAD_USAGE

:TEMP_NAME
set TMPFILE=%TMP%\%RANDOM%_ftpupload.tmp
if exist "%TMPFILE%" goto TEMP_NAME 

SET INITIALDIR=%CD%

echo user %FTPUSERNAME% %FTPPASSWORD% > %TMPFILE%
echo bin >> %TMPFILE%
echo lcd %LOCALDIR% >> %TMPFILE%

cd %LOCALDIR%

setlocal EnableDelayedExpansion
echo mkdir !REMOTEDIR! >> !TMPFILE!
echo cd %REMOTEDIR% >> !TMPFILE!
echo mput * >> !TMPFILE!
for /d /r %%d in (*) do (
    set CURRENT_DIRECTORY=%%d
    set RELATIVE_DIRECTORY=!CURRENT_DIRECTORY:%LOCALDIR%=!
    echo mkdir "!REMOTEDIR!/!RELATIVE_DIRECTORY:~1!" >> !TMPFILE!
    echo cd "!REMOTEDIR!/!RELATIVE_DIRECTORY:~1!" >> !TMPFILE!
    echo mput "!RELATIVE_DIRECTORY:~1!\*" >> !TMPFILE!
)

echo quit >> !TMPFILE!

endlocal EnableDelayedExpansion

ftp -n -i "-s:%TMPFILE%" %FTPADDRESS%

del %TMPFILE%

cd %INITIALDIR%

goto FTP_UPLOAD_EXIT

:FTP_UPLOAD_USAGE

echo Usage: ftpupload [address] [username] [password] [local directory] [remote directory]
echo.

:FTP_UPLOAD_EXIT

set INITIALDIR=
set FTPADDRESS=
set FTPUSERNAME=
set FTPPASSWORD=
set LOCALDIR=
set REMOTEDIR=
set TMPFILE=
set CURRENT_DIRECTORY=
set RELATIVE_DIRECTORY=

@echo on

ftpget.bat

@echo off

SET FTPADDRESS=%1
SET FTPUSERNAME=%2
SET FTPPASSWORD=%3
SET LOCALDIR=%~f4
SET REMOTEDIR=%5
SET REMOTEFILE=%6

if "%FTPADDRESS%" == "" goto FTP_UPLOAD_USAGE
if "%FTPUSERNAME%" == "" goto FTP_UPLOAD_USAGE
if "%FTPPASSWORD%" == "" goto FTP_UPLOAD_USAGE
if "%LOCALDIR%" == "" goto FTP_UPLOAD_USAGE
if not defined REMOTEDIR goto FTP_UPLOAD_USAGE
if not defined REMOTEFILE goto FTP_UPLOAD_USAGE

:TEMP_NAME
set TMPFILE=%TMP%\%RANDOM%_ftpupload.tmp
if exist "%TMPFILE%" goto TEMP_NAME 

echo user %FTPUSERNAME% %FTPPASSWORD% > %TMPFILE%
echo bin >> %TMPFILE%
echo lcd %LOCALDIR% >> %TMPFILE%

echo cd "%REMOTEDIR%" >> %TMPFILE%
echo mget "%REMOTEFILE%" >> %TMPFILE%
echo quit >> %TMPFILE%

ftp -n -i "-s:%TMPFILE%" %FTPADDRESS%

del %TMPFILE%

goto FTP_UPLOAD_EXIT

:FTP_UPLOAD_USAGE

echo Usage: ftpget [address] [username] [password] [local directory] [remote directory] [remote file pattern]
echo.

:FTP_UPLOAD_EXIT

set FTPADDRESS=
set FTPUSERNAME=
set FTPPASSWORD=
set LOCALDIR=
set REMOTEFILE=
set REMOTEDIR=
set TMPFILE=
set CURRENT_DIRECTORY=
set RELATIVE_DIRECTORY=

@echo on

jquery beforeunload when closing (not leaving) the page?

Credit should go here: how to detect if a link was clicked when window.onbeforeunload is triggered?

Basically, the solution adds a listener to detect if a link or window caused the unload event to fire.

var link_was_clicked = false;
document.addEventListener("click", function(e) {
   if (e.target.nodeName.toLowerCase() === 'a') {
      link_was_clicked = true;
   }
}, true);

window.onbeforeunload = function(e) {
    if(link_was_clicked) {
        return;
    }
    return confirm('Are you sure?');
}

Can't execute jar- file: "no main manifest attribute"

(first post - so it may not be clean)

This is my fix for OS X 11.6, Maven-based Netbeans 8.2 program. Up to now my app is 100% Netbeans - no tweaking (just a few shell escapes for the impossible!).

Having tried most all of the answers here and elsewhere to no avail, I returned to the art of "use what works".

The top answer here (olivier-refalo thanx) looked like the right place to start but didn't help.

Looking at other projects which did work, I noticed some minor differences in the manifest lines:

  1. addClasspath, classpathPrefix were absent (deleted them)
  2. mainClass was missing the "com." (used the NB -> Project Properties->Run->Main Class->Browse to specify)

Not sure why (I am only 3 months into java) or how, but can only say this worked.

Here is just the modified manifest block used:

    <manifest>
        <mainClass>mypackage.MyClass</mainClass>
    </manifest>

Accessing a value in a tuple that is in a list

You can also use sequence unpacking with zip:

L = [(1,2),(2,3),(4,5),(3,4),(6,7),(6,7),(3,8)]

_, res = zip(*L)

print(res)

# (2, 3, 5, 4, 7, 7, 8)

This also creates a tuple _ from the discarded first elements. Extracting only the second is possible, but more verbose:

from itertools import islice

res = next(islice(zip(*L), 1, None))

Find objects between two dates MongoDB

Why not convert the string to an integer of the form YYYYMMDDHHMMSS? Each increment of time would then create a larger integer, and you can filter on the integers instead of worrying about converting to ISO time.

What is a unix command for deleting the first N characters of a line?

tail -f logfile | grep org.springframework | cut -c 900-

would remove the first 900 characters

cut uses 900- to show the 900th character to the end of the line

however when I pipe all of this through grep I don't get anything

How to run code after some delay in Flutter?

You can use Future.delayed to run your code after some time. e.g.:

Future.delayed(const Duration(milliseconds: 500), () {

// Here you can write your code

  setState(() {
    // Here you can write your code for open new view
  });

});

In setState function, you can write a code which is related to app UI e.g. refresh screen data, change label text, etc.

The relationship could not be changed because one or more of the foreign-key properties is non-nullable

You must manually clear the ChildItems collection and append new items into it:

thisParent.ChildItems.Clear();
thisParent.ChildItems.AddRange(modifiedParent.ChildItems);

After that you can call DeleteOrphans extension method which will handle with orphaned entities (it must be called between DetectChanges and SaveChanges methods).

public static class DbContextExtensions
{
    private static readonly ConcurrentDictionary< EntityType, ReadOnlyDictionary< string, NavigationProperty>> s_navPropMappings = new ConcurrentDictionary< EntityType, ReadOnlyDictionary< string, NavigationProperty>>();

    public static void DeleteOrphans( this DbContext source )
    {
        var context = ((IObjectContextAdapter)source).ObjectContext;
        foreach (var entry in context.ObjectStateManager.GetObjectStateEntries(EntityState.Modified))
        {
            var entityType = entry.EntitySet.ElementType as EntityType;
            if (entityType == null)
                continue;

            var navPropMap = s_navPropMappings.GetOrAdd(entityType, CreateNavigationPropertyMap);
            var props = entry.GetModifiedProperties().ToArray();
            foreach (var prop in props)
            {
                NavigationProperty navProp;
                if (!navPropMap.TryGetValue(prop, out navProp))
                    continue;

                var related = entry.RelationshipManager.GetRelatedEnd(navProp.RelationshipType.FullName, navProp.ToEndMember.Name);
                var enumerator = related.GetEnumerator();
                if (enumerator.MoveNext() && enumerator.Current != null)
                    continue;

                entry.Delete();
                break;
            }
        }
    }

    private static ReadOnlyDictionary<string, NavigationProperty> CreateNavigationPropertyMap( EntityType type )
    {
        var result = type.NavigationProperties
            .Where(v => v.FromEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many)
            .Where(v => v.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.One || (v.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.ZeroOrOne && v.FromEndMember.GetEntityType() == v.ToEndMember.GetEntityType()))
            .Select(v => new { NavigationProperty = v, DependentProperties = v.GetDependentProperties().Take(2).ToArray() })
            .Where(v => v.DependentProperties.Length == 1)
            .ToDictionary(v => v.DependentProperties[0].Name, v => v.NavigationProperty);

        return new ReadOnlyDictionary<string, NavigationProperty>(result);
    }
}

How can multiple rows be concatenated into one in Oracle without creating a stored procedure?

There are many way to do the string aggregation, but the easiest is a user defined function. Try this for a way that does not require a function. As a note, there is no simple way without the function.

This is the shortest route without a custom function: (it uses the ROW_NUMBER() and SYS_CONNECT_BY_PATH functions )

SELECT questionid,
       LTRIM(MAX(SYS_CONNECT_BY_PATH(elementid,','))
       KEEP (DENSE_RANK LAST ORDER BY curr),',') AS elements
FROM   (SELECT questionid,
               elementid,
               ROW_NUMBER() OVER (PARTITION BY questionid ORDER BY elementid) AS curr,
               ROW_NUMBER() OVER (PARTITION BY questionid ORDER BY elementid) -1 AS prev
        FROM   emp)
GROUP BY questionid
CONNECT BY prev = PRIOR curr AND questionid = PRIOR questionid
START WITH curr = 1;

Run two async tasks in parallel and collect results in .NET 4.5

async Task<int> LongTask1() { 
  ...
  return 0; 
}

async Task<int> LongTask2() { 
  ...
  return 1; 
}

...
{
   Task<int> t1 = LongTask1();
   Task<int> t2 = LongTask2();
   await Task.WhenAll(t1,t2);
   //now we have t1.Result and t2.Result
}

Is it possible to break a long line to multiple lines in Python?

When trying to enter continuous text (say, a query) do not put commas at the end of the line or you will get a list of strings instead of one long string:

queryText= "SELECT * FROM TABLE1 AS T1"\
"JOIN TABLE2 AS T2 ON T1.SOMETHING = T2.SOMETHING"\
"JOIN TABLE3 AS T3 ON T3.SOMETHING = T2.SOMETHING"\
"WHERE SOMETHING BETWEEN <WHATEVER> AND <WHATEVER ELSE>"\
"ORDER BY WHATEVERS DESC"

kinda like that.

There is a comment like this from acgtyrant, sorry, didn't see that. :/

Android ADB doesn't see device

Some of these answers are pretty old, so maybe it's changed in recent times, but I had similar issues and I solved it by:

  1. Loading the USB drivers for the device - Samsung S6
  2. Enable Developer tools on the phone.
  3. On the device, go to Settings - Applications - Development - Check USB Debugging
  4. Reboot O/S (Windows 7 - 64bit)
  5. Open Visual Studio

I think it was step 3 that had me stumped for a while. I'd enabled developer tools, but I didn't specifically enable the "USB Debugging" but.

What is difference between arm64 and armhf?

Update: Yes, I understand that this answer does not explain the difference between arm64 and armhf. There is a great answer that does explain that on this page. This answer was intended to help set the asker on the right path, as they clearly had a misunderstanding about the capabilities of the Raspberry Pi at the time of asking.

Where are you seeing that the architecture is armhf? On my Raspberry Pi 3, I get:

$ uname -a
armv7l

Anyway, armv7 indicates that the system architecture is 32-bit. The first ARM architecture offering 64-bit support is armv8. See this table for reference.

You are correct that the CPU in the Raspberry Pi 3 is 64-bit, but the Raspbian OS has not yet been updated for a 64-bit device. 32-bit software can run on a 64-bit system (but not vice versa). This is why you're not seeing the architecture reported as 64-bit.

You can follow the GitHub issue for 64-bit support here, if you're interested.

How to escape special characters of a string with single backslashes

Just assuming this is for a regular expression, use re.escape.

POST string to ASP.NET Web Api application - returns null

Web API works very nicely if you accept the fact that you are using HTTP. It's when you start trying to pretend that you are sending objects over the wire that it starts to get messy.

 public class TextController : ApiController
    {
        public HttpResponseMessage Post(HttpRequestMessage request) {

            var someText = request.Content.ReadAsStringAsync().Result;
            return new HttpResponseMessage() {Content = new StringContent(someText)};

        }

    }

This controller will handle a HTTP request, read a string out of the payload and return that string back.

You can use HttpClient to call it by passing an instance of StringContent. StringContent will be default use text/plain as the media type. Which is exactly what you are trying to pass.

    [Fact]
    public void PostAString()
    {

        var client = new HttpClient();

        var content = new StringContent("Some text");
        var response = client.PostAsync("http://oak:9999/api/text", content).Result;

        Assert.Equal("Some text",response.Content.ReadAsStringAsync().Result);

    }

Is std::vector copying the objects with a push_back?

From C++11 onwards, all the standard containers (std::vector, std::map, etc) support move semantics, meaning that you can now pass rvalues to standard containers and avoid a copy:

// Example object class.
class object
{
private:
    int             m_val1;
    std::string     m_val2;

public:
    // Constructor for object class.
    object(int val1, std::string &&val2) :
        m_val1(val1),
        m_val2(std::move(val2))
    {

    }
};

std::vector<object> myList;

// #1 Copy into the vector.
object foo1(1, "foo");
myList.push_back(foo1);

// #2 Move into the vector (no copy).
object foo2(1024, "bar");
myList.push_back(std::move(foo2));

// #3 Move temporary into vector (no copy).
myList.push_back(object(453, "baz"));

// #4 Create instance of object directly inside the vector (no copy, no move).
myList.emplace_back(453, "qux");

Alternatively you can use various smart pointers to get mostly the same effect:

std::unique_ptr example

std::vector<std::unique_ptr<object>> myPtrList;

// #5a unique_ptr can only ever be moved.
auto pFoo = std::make_unique<object>(1, "foo");
myPtrList.push_back(std::move(pFoo));

// #5b unique_ptr can only ever be moved.
myPtrList.push_back(std::make_unique<object>(1, "foo"));

std::shared_ptr example

std::vector<std::shared_ptr<object>> objectPtrList2;

// #6 shared_ptr can be used to retain a copy of the pointer and update both the vector
// value and the local copy simultaneously.
auto pFooShared = std::make_shared<object>(1, "foo");
objectPtrList2.push_back(pFooShared);
// Pointer to object stored in the vector, but pFooShared is still valid.

LINQ to SQL - How to select specific columns and return strongly typed list

Make a call to the DB searching with myid (Id of the row) and get back specific columns:

var columns = db.Notifications
                .Where(x => x.Id == myid)
                .Select(n => new { n.NotificationTitle, 
                                   n.NotificationDescription, 
                                   n.NotificationOrder });

Include CSS and Javascript in my django template

Refer django docs on static files.

In settings.py:

import os
CURRENT_PATH = os.path.abspath(os.path.dirname(__file__).decode('utf-8'))

MEDIA_ROOT = os.path.join(CURRENT_PATH, 'media')

MEDIA_URL = '/media/'

STATIC_ROOT = 'static/'

STATIC_URL = '/static/'

STATICFILES_DIRS = (
                    os.path.join(CURRENT_PATH, 'static'),
)

Then place your js and css files static folder in your project. Not in media folder.

In views.py:

from django.shortcuts import render_to_response, RequestContext

def view_name(request):
    #your stuff goes here
    return render_to_response('template.html', locals(), context_instance = RequestContext(request))

In template.html:

<link rel="stylesheet" type="text/css" href="{{ STATIC_URL }}css/style.css" />
<script type="text/javascript" src="{{ STATIC_URL }}js/jquery-1.8.3.min.js"></script>

In urls.py:

from django.conf import settings
urlpatterns += patterns('',
    url(r'^media/(?P<path>.*)$', 'django.views.static.serve', {'document_root': settings.MEDIA_ROOT, 'show_indexes': True}),
)

Project file structure can be found here in imgbin.

Transfer git repositories from GitLab to GitHub - can we, how to and pitfalls (if any)?

For anyone still looking for a simpler method to transfer repos from Gitlab to Github while preserving all history.

Step 1. Login to Github, create a private repo with the exact same name as the repo you would like to transfer.

Step 2. Under "push an existing repository from the command" copy the link of the new repo, it will look something like this:

[email protected]:your-name/name-of-repo.git

Step 3. Open up your local project and look for the folder .git typically this will be a hidden folder. Inside the .git folder open up config.

The config file will contain something like:

[remote "origin"]
url = [email protected]:your-name/name-of-repo.git
fetch = +refs/heads/:refs/remotes/origin/

Under [remote "origin"], change the URL to the one that you copied on Github.

Step 4. Open your project folder in the terminal and run: git push --all. This will push your code to Github as well as all the commit history.

Step 5. To make sure everything is working as expected, make changes, commit, push and new commits should appear on the newly created Github repo.

Step 6. As a last step, you can now archive your Gitlab repo or set it to read only.

Powershell: How can I stop errors from being displayed in a script?

I had a similar problem when trying to resolve host names using [system.net.dns]. If the IP wasn't resolved .Net threw a terminating error. To prevent the terminating error and still retain control of the output, I created a function using TRAP.

E.G.

Function Get-IP 
{PARAM   ([string]$HostName="")
PROCESS {TRAP 
             {"" ;continue} 
             [system.net.dns]::gethostaddresses($HostName)
        }
}

DB2 SQL error: SQLCODE: -206, SQLSTATE: 42703

That only means that an undefined column or parameter name was detected. The errror that DB2 gives should point what that may be:

DB2 SQL Error: SQLCODE=-206, SQLSTATE=42703, SQLERRMC=[THE_UNDEFINED_COLUMN_OR_PARAMETER_NAME], DRIVER=4.8.87

Double check your table definition. Maybe you just missed adding something.

I also tried google-ing this problem and saw this:

http://www.coderanch.com/t/515475/JDBC/databases/sql-insert-statement-giving-sqlcode

Batch file to copy files from one folder to another folder

xcopy.exe is definitely your friend here. It's built into Windows, so its cost is nothing.

Just xcopy /s c:\source d:\target

You'd probably want to tweak a few things; some of the options we also add include these:

  • /s/e - recursive copy, including copying empty directories.
  • /v - add this to verify the copy against the original. slower, but for the paranoid.
  • /h - copy system and hidden files.
  • /k - copy read-only attributes along with files. otherwise, all files become read-write.
  • /x - if you care about permissions, you might want /o or /x.
  • /y - don't prompt before overwriting existing files.
  • /z - if you think the copy might fail and you want to restart it, use this. It places a marker on each file as it copies, so you can rerun the xcopy command to pick up from where it left off.

If you think the xcopy might fail partway through (like when you are copying over a flaky network connection), or that you have to stop it and want to continue it later, you can use xcopy /s/z c:\source d:\target.

Hope this helps.

"An access token is required to request this resource" while accessing an album / photo with Facebook php sdk

To get an access token: facebook Graph API Explorer

You can customize specific access permissions, basic permissions are included by default.

What is the difference between smoke testing and sanity testing?

Smoke testing

Smoke testing came from the hardware environment where testing should be done to check whether the development of a new piece of hardware causes no fire and smoke for the first time.

In the software environment, smoke testing is done to verify whether we can consider for further testing the functionality which is newly built.

Sanity testing

A subset of regression test cases are executed after receiving a functionality or code with small or minor changes in the functionality or code, to check whether it resolved the issues or software bugs and no other software bug is introduced by the new changes.


Difference between smoke testing and sanity testing

Smoke testing

  • Smoke testing is used to test all areas of the application without going into too deep.

  • A smoke test always use an automated test or a written set of tests. It is always scripted.

  • Smoke testing is designed to include every part of the application in a not thorough or detailed way.

  • Smoke testing always ensures whether the most crucial functions of a program are working, but not bothering with finer details.

Sanity testing

  • Sanity testing is a narrow test that focuses on one or a few areas of functionality, but not thoroughly or in-depth.

  • A sanity test is usually unscripted.

  • Sanity testing is used to ensure that after a minor change a small part of the application is still working.

  • Sanity testing is a cursory testing, which is performed to prove that the application is functioning according to the specifications. This level of testing is a subset of regression testing.

Hope these points help you to understand the difference between smoke testing and sanity testing.


References

Custom ImageView with drop shadow

I manage to apply gradient border using this code..

public static Bitmap drawShadow(Bitmap bitmap, int leftRightThk, int bottomThk, int padTop) {
    int w = bitmap.getWidth();
    int h = bitmap.getHeight();

    int newW = w - (leftRightThk * 2);
    int newH = h - (bottomThk + padTop);

    Bitmap.Config conf = Bitmap.Config.ARGB_8888;
    Bitmap bmp = Bitmap.createBitmap(w, h, conf);
    Bitmap sbmp = Bitmap.createScaledBitmap(bitmap, newW, newH, false);

    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    Canvas c = new Canvas(bmp);

    // Left
    int leftMargin = (leftRightThk + 7)/2;
    Shader lshader = new LinearGradient(0, 0, leftMargin, 0, Color.TRANSPARENT, Color.BLACK, TileMode.CLAMP);
    paint.setShader(lshader);
    c.drawRect(0, padTop, leftMargin, newH, paint); 

    // Right
    Shader rshader = new LinearGradient(w - leftMargin, 0, w, 0, Color.BLACK, Color.TRANSPARENT, TileMode.CLAMP);
    paint.setShader(rshader);
    c.drawRect(newW, padTop, w, newH, paint);

    // Bottom
    Shader bshader = new LinearGradient(0, newH, 0, bitmap.getHeight(), Color.BLACK, Color.TRANSPARENT, TileMode.CLAMP);
    paint.setShader(bshader);
    c.drawRect(leftMargin -3, newH, newW + leftMargin + 3, bitmap.getHeight(), paint);
    c.drawBitmap(sbmp, leftRightThk, 0, null);

    return bmp;
}

hope this helps !

Laravel where on relationship object

With multiple joins, use something like this code:

$someId = 44;
Event::with(["owner", "participants" => function($q) use($someId){
    $q->where('participants.IdUser', '=', 1);
    //$q->where('some other field', $someId);
}])

What is the difference between Session.Abandon() and Session.Clear()

this code works and dont throw any exception:

Session.Abandon();  
Session["tempKey1"] = "tempValue1";

It's because when the Abandon method is called, the current Session object is queued for deletion but is not actually deleted until all of the script commands on the current page have been processed. This means that you can access variables stored in the Session object on the same page as the call to the Abandon method but not in any subsequent Web pages.

For example, in the following script, the third line prints the value Mary. This is because the Session object is not destroyed until the server has finished processing the script.

<% 
  Session.Abandon  
  Session("MyName") = "Mary" 
  Reponse.Write(Session("MyName")) 
%>

If you access the variable MyName on a subsequent Web page, it is empty. This is because MyName was destroyed with the previous Session object when the page containing the previous example finished processing.

from MSDN Session.Abandon

A html space is showing as %2520 instead of %20

A bit of explaining as to what that %2520 is :

The common space character is encoded as %20 as you noted yourself. The % character is encoded as %25.

The way you get %2520 is when your url already has a %20 in it, and gets urlencoded again, which transforms the %20 to %2520.

Are you (or any framework you might be using) double encoding characters?

Edit: Expanding a bit on this, especially for LOCAL links. Assuming you want to link to the resource C:\my path\my file.html:

  • if you provide a local file path only, the browser is expected to encode and protect all characters given (in the above, you should give it with spaces as shown, since % is a valid filename character and as such it will be encoded) when converting to a proper URL (see next point).
  • if you provide a URL with the file:// protocol, you are basically stating that you have taken all precautions and encoded what needs encoding, the rest should be treated as special characters. In the above example, you should thus provide file:///c:/my%20path/my%20file.html. Aside from fixing slashes, clients should not encode characters here.

NOTES:

  • Slash direction - forward slashes / are used in URLs, reverse slashes \ in Windows paths, but most clients will work with both by converting them to the proper forward slash.
  • In addition, there are 3 slashes after the protocol name, since you are silently referring to the current machine instead of a remote host ( the full unabbreviated path would be file://localhost/c:/my%20path/my%file.html ), but again most clients will work without the host part (ie two slashes only) by assuming you mean the local machine and adding the third slash.

How to solve a pair of nonlinear equations using Python?

Short answer: use fsolve

As mentioned in other answers the simplest solution to the particular problem you have posed is to use something like fsolve:

from scipy.optimize import fsolve
from math import exp

def equations(vars):
    x, y = vars
    eq1 = x+y**2-4
    eq2 = exp(x) + x*y - 3
    return [eq1, eq2]

x, y =  fsolve(equations, (1, 1))

print(x, y)

Output:

0.6203445234801195 1.8383839306750887

Analytic solutions?

You say how to "solve" but there are different kinds of solution. Since you mention SymPy I should point out the biggest difference between what this could mean which is between analytic and numeric solutions. The particular example you have given is one that does not have an (easy) analytic solution but other systems of nonlinear equations do. When there are readily available analytic solutions SymPY can often find them for you:

from sympy import *

x, y = symbols('x, y')
eq1 = Eq(x+y**2, 4)
eq2 = Eq(x**2 + y, 4)

sol = solve([eq1, eq2], [x, y])

Output:

?? ?  5   v17? ?3   v17?    v17   1?  ? ?  5   v17? ?3   v17?    1   v17?  ? ?  3   v13? ?v13   5?  1   v13?  ? ?5   v13? ?  v13   3?  1   v13??
??-?- - - ---?·?- - ---?, - --- - -?, ?-?- - + ---?·?- + ---?, - - + ---?, ?-?- - + ---?·?--- + -?, - + ---?, ?-?- - ---?·?- --- - -?, - - ---??
?? ?  2    2 ? ?2    2 ?     2    2?  ? ?  2    2 ? ?2    2 ?    2    2 ?  ? ?  2    2 ? ? 2    2?  2    2 ?  ? ?2    2 ? ?   2    2?  2    2 ??

Note that in this example SymPy finds all solutions and does not need to be given an initial estimate.

You can evaluate these solutions numerically with evalf:

soln = [tuple(v.evalf() for v in s) for s in sol]
[(-2.56155281280883, -2.56155281280883), (1.56155281280883, 1.56155281280883), (-1.30277563773199, 2.30277563773199), (2.30277563773199, -1.30277563773199)]

Precision of numeric solutions

However most systems of nonlinear equations will not have a suitable analytic solution so using SymPy as above is great when it works but not generally applicable. That is why we end up looking for numeric solutions even though with numeric solutions: 1) We have no guarantee that we have found all solutions or the "right" solution when there are many. 2) We have to provide an initial guess which isn't always easy.

Having accepted that we want numeric solutions something like fsolve will normally do all you need. For this kind of problem SymPy will probably be much slower but it can offer something else which is finding the (numeric) solutions more precisely:

from sympy import *

x, y = symbols('x, y')
nsolve([Eq(x+y**2, 4), Eq(exp(x)+x*y, 3)], [x, y], [1, 1])
?0.620344523485226?
?                 ?
?1.83838393066159 ?

With greater precision:

nsolve([Eq(x+y**2, 4), Eq(exp(x)+x*y, 3)], [x, y], [1, 1], prec=50)
?0.62034452348522585617392716579154399314071550594401?
?                                                    ?
? 1.838383930661594459049793153371142549403114879699 ?

sequelize findAll sort order in nodejs

You can accomplish this in a very back-handed way with the following code:

exports.getStaticCompanies = function () {
    var ids = [46128, 2865, 49569, 1488, 45600, 61991, 1418, 61919, 53326, 61680]
    return Company.findAll({
        where: {
            id: ids
        },
        attributes: ['id', 'logo_version', 'logo_content_type', 'name', 'updated_at'],
        order: sequelize.literal('(' + ids.map(function(id) {
            return '"Company"."id" = \'' + id + '\'');
        }).join(', ') + ') DESC')
    });
};

This is somewhat limited because it's got very bad performance characteristics past a few dozen records, but it's acceptable at the scale you're using.

This will produce a SQL query that looks something like this:

[...] ORDER BY ("Company"."id"='46128', "Company"."id"='2865', "Company"."id"='49569', [...])

How to remove old Docker containers

You can remove the containers using multiple ways that I will explain them in the rest of the answer.

  1. docker container prune. This command removes the all of the containers that are not working right now. You can find out which containers are not working by comparing the output of docker ps and docker ps -a. The containers that are listed in docker ps -a and not exist in docker ps are not working right now, but their containers aren't removed.

  2. docker kill $(docker ps -aq). What this command does is that by executing $(docker ps -aq) it returns the list of ids of all containers and kill them. Sometime this command doesn't work because it is being using by the running container. To make that work, you can use --force option.

  3. docker rm $(docker ps -aq). It has the same definition as the second command. The only difference of them is that it removes the container (as same as docker prune), while the docker kill doesn't.

  4. Sometimes it is needed to remove the image, because you have changed the configuration of the Dockerfile and need to remove it to rebuild it. For this purpose you can see all of the images by running docker images and then copy the ID of the image that you want to remove. It can be deleted simply by executing docker image rm <image-id>.

PS: You can use docker ps -a -q instead of docker ps -aq and there is no differences. Because in unix-based operating system, you can join the options like the above example.

How to update one file in a zip archive

From the side of ZIP archive structure - you can update zip file without recompressing it, you will just need to skip all files which are prior of the file you need to replace, then put your updated file, and then the rest of the files. And finally you'll need to put the updated centeral directory structure. However, I doubt that most common tools would allow you to make this.

Hibernate Auto Increment ID

FYI

Using netbeans New Entity Classes from Database with a mysql *auto_increment* column, creates you an attribute with the following annotations:

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "id")
@NotNull
private Integer id;

This was getting me the same an error saying the column must not be null, so i simply removed the @NotNull anotation leaving the attribute null, and it works!

Django ManyToMany filter()

Just restating what Tomasz said.

There are many examples of FOO__in=... style filters in the many-to-many and many-to-one tests. Here is syntax for your specific problem:

users_in_1zone = User.objects.filter(zones__id=<id1>)
# same thing but using in
users_in_1zone = User.objects.filter(zones__in=[<id1>])

# filtering on a few zones, by id
users_in_zones = User.objects.filter(zones__in=[<id1>, <id2>, <id3>])
# and by zone object (object gets converted to pk under the covers)
users_in_zones = User.objects.filter(zones__in=[zone1, zone2, zone3])

The double underscore (__) syntax is used all over the place when working with querysets.

Disable back button in android

Simply override the onBackPressed() method.

@Override
public void onBackPressed() { }

How to set HTML Auto Indent format on Sublime Text 3?

This was bugging me too, since this was a standard feature in Sublime Text 2, but somehow automatic indentation no longer worked in Sublime Text 3 for HTML files.

My solution was to find the Miscellaneous.tmPreferences file from Sublime Text 2 (found under %AppData%/Roaming/Sublime Text 2/Packages/HTML) and copy those settings to the same file for ST3.

Now package handling has been made more difficult for ST3, but luckily you can just add the files to your %AppData%/Roaming/Sublime Text 3/Packages folder and they overwrite default settings in the install directory. Just save this file as "%AppData%/Roaming/Sublime Text 3/Packages/HTML/Miscellaneous.tmPreferences" and auto indent works again like it did in ST2.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>name</key>
    <string>Miscellaneous</string>
    <key>scope</key>
    <string>text.html</string>
    <key>settings</key>
    <dict>
        <key>decreaseIndentPattern</key>
            <string>(?x)
            ^\s*
            (&lt;/(?!html)
              [A-Za-z0-9]+\b[^&gt;]*&gt;
            |--&gt;
            |&lt;\?(php)?\s+(else(if)?|end(if|for(each)?|while))
            |\}
            )</string>
        <key>batchDecreaseIndentPattern</key>
            <string>(?x)
            ^\s*
            (&lt;/(?!html)
              [A-Za-z0-9]+\b[^&gt;]*&gt;
            |--&gt;
            |&lt;\?(php)?\s+(else(if)?|end(if|for(each)?|while))
            |\}
            )</string>
        <key>increaseIndentPattern</key>
            <string>(?x)
            ^\s*
            &lt;(?!\?|area|base|br|col|frame|hr|html|img|input|link|meta|param|[^&gt;]*/&gt;)
              ([A-Za-z0-9]+)(?=\s|&gt;)\b[^&gt;]*&gt;(?!.*&lt;/\1&gt;)
            |&lt;!--(?!.*--&gt;)
            |&lt;\?php.+?\b(if|else(?:if)?|for(?:each)?|while)\b.*:(?!.*end\1)
            |\{[^}"']*$
            </string>
        <key>batchIncreaseIndentPattern</key>
            <string>(?x)
            ^\s*
            &lt;(?!\?|area|base|br|col|frame|hr|html|img|input|link|meta|param|[^&gt;]*/&gt;)
              ([A-Za-z0-9]+)(?=\s|&gt;)\b[^&gt;]*&gt;(?!.*&lt;/\1&gt;)
            |&lt;!--(?!.*--&gt;)
            |&lt;\?php.+?\b(if|else(?:if)?|for(?:each)?|while)\b.*:(?!.*end\1)
            |\{[^}"']*$
            </string>
        <key>bracketIndentNextLinePattern</key>
         <string>&lt;!DOCTYPE(?!.*&gt;)</string>
    </dict>
</dict>
</plist>

Force Java timezone as GMT/UTC

Also if you can set JVM timezone this way

System.setProperty("user.timezone", "EST");

or -Duser.timezone=GMT in the JVM args.

How to determine a Python variable's type?

Python doesn't have such types as you describe. There are two types used to represent integral values: int, which corresponds to platform's int type in C, and long, which is an arbitrary precision integer (i.e. it grows as needed and doesn't have an upper limit). ints are silently converted to long if an expression produces result which cannot be stored in int.

Visual Studio displaying errors even if projects build

Perhaps you try to reset your intellisense cache. I've had a similar issue in visual studio 2012 when working in a large project with many partial class definitions. Reducing the partials solved the problem partially, clearing the intellisense cache also - for a while.

Asp.net - Add blank item at top of dropdownlist

Do your databinding and then add the following:

Dim liFirst As New ListItem("", "")
drpList.Items.Insert(0, liFirst)

What is the easiest way to parse an INI file in Java?

Another option is Apache Commons Config also has a class for loading from INI files. It does have some runtime dependencies, but for INI files it should only require Commons collections, lang, and logging.

I've used Commons Config on projects with their properties and XML configurations. It is very easy to use and supports some pretty powerful features.

trace a particular IP and port

You can use the default traceroute command for this purpose, then there will be nothing to install.

traceroute -T -p 9100 <IP address/hostname>

The -T argument is required so that the TCP protocol is used instead of UDP.

In the rare case when traceroute isn't available, you can also use ncat.

nc -Czvw 5 <IP address/hostname> 9100

Does delete on a pointer to a subclass call the base class destructor?

You have something like

class B
{
   A * a;
}
B * b = new B;
b->a = new A;

If you then call delete b;, nothing happens to a, and you have a memory leak. Trying to remember to delete b->a; is not a good solution, but there are a couple of others.

B::~B() {delete a;}

This is a destructor for B that will delete a. (If a is 0, that delete does nothing. If a is not 0 but doesn't point to memory from new, you get heap corruption.)

auto_ptr<A> a;
...
b->a.reset(new A);

This way you don't have a as a pointer, but rather an auto_ptr<> (shared_ptr<> will do as well, or other smart pointers), and it is automatically deleted when b is.

Either of these ways works well, and I've used both.

Make Error 127 when running trying to compile code

Error 127 means one of two things:

  1. file not found: the path you're using is incorrect. double check that the program is actually in your $PATH, or in this case, the relative path is correct -- remember that the current working directory for a random terminal might not be the same for the IDE you're using. it might be better to just use an absolute path instead.
  2. ldso is not found: you're using a pre-compiled binary and it wants an interpreter that isn't on your system. maybe you're using an x86_64 (64-bit) distro, but the prebuilt is for x86 (32-bit). you can determine whether this is the answer by opening a terminal and attempting to execute it directly. or by running file -L on /bin/sh (to get your default/native format) and on the compiler itself (to see what format it is).

if the problem is (2), then you can solve it in a few diff ways:

  1. get a better binary. talk to the vendor that gave you the toolchain and ask them for one that doesn't suck.
  2. see if your distro can install the multilib set of files. most x86_64 64-bit distros allow you to install x86 32-bit libraries in parallel.
  3. build your own cross-compiler using something like crosstool-ng.
  4. you could switch between an x86_64 & x86 install, but that seems a bit drastic ;).

Skip over a value in the range function in python

It depends on what you want to do. For example you could stick in some conditionals like this in your comprehensions:

# get the squares of each number from 1 to 9, excluding 2
myList = [i**2 for i in range(10) if i != 2]
print(myList)

# --> [0, 1, 9, 16, 25, 36, 49, 64, 81]

Insert, on duplicate update in PostgreSQL?

I have the same issue for managing account settings as name value pairs. The design criteria is that different clients could have different settings sets.

My solution, similar to JWP is to bulk erase and replace, generating the merge record within your application.

This is pretty bulletproof, platform independent and since there are never more than about 20 settings per client, this is only 3 fairly low load db calls - probably the fastest method.

The alternative of updating individual rows - checking for exceptions then inserting - or some combination of is hideous code, slow and often breaks because (as mentioned above) non standard SQL exception handling changing from db to db - or even release to release.

 #This is pseudo-code - within the application:
 BEGIN TRANSACTION - get transaction lock
 SELECT all current name value pairs where id = $id into a hash record
 create a merge record from the current and update record
  (set intersection where shared keys in new win, and empty values in new are deleted).
 DELETE all name value pairs where id = $id
 COPY/INSERT merged records 
 END TRANSACTION

How to obfuscate Python code effectively?

You could embed your code in C/C++ and compile Embedding Python in Another Application

embedded.c

#include <Python.h>

int
main(int argc, char *argv[])
{
  Py_SetProgramName(argv[0]);  /* optional but recommended */
  Py_Initialize();
  PyRun_SimpleString("print('Hello world !')");
  Py_Finalize();
  return 0;
}

In Ubuntu/Debian

$ sudo apt-get install python-dev

In Centos/Redhat/Fedora

$ sudo yum install python-devel

compile with

$ gcc -o embedded -fPIC -I/usr/include/python2.7 -lpython2.7 embedded.c

run with

$ chmod u+x ./embedded
$ time ./embedded
Hello world !

real  0m0.014s
user  0m0.008s
sys 0m0.004s

initial script: hello_world.py:

print('Hello World !')

run the script

$ time python hello_world.py
Hello World !

real  0m0.014s
user  0m0.008s
sys 0m0.004s

however some strings of the python code may be found in the compiled file

$ grep "Hello" ./embedded
Binary file ./embedded matches

$ grep "Hello World" ./embedded
$

In case you want an extra bit of obfuscation you could use base64

...
PyRun_SimpleString("import base64\n"
                  "base64_code = 'your python code in base64'\n"
                  "code = base64.b64decode(base64_code)\n"
                  "exec(code)");
...

e.g:

create the base 64 string of your code

$ base64 hello_world.py
cHJpbnQoJ0hlbGxvIFdvcmxkICEnKQoK

embedded_base64.c

#include <Python.h>

int
main(int argc, char *argv[])
{
  Py_SetProgramName(argv[0]);  /* optional but recommended */
  Py_Initialize();
  PyRun_SimpleString("import base64\n"
                    "base64_code = 'cHJpbnQoJ0hlbGxvIFdvcmxkICEnKQoK'\n"
                    "code = base64.b64decode(base64_code)\n"
                    "exec(code)\n");
  Py_Finalize();
  return 0;
}

all commands

$ gcc -o embedded_base64 -fPIC -I/usr/include/python2.7 -lpython2.7 ./embedded_base64.c
$ chmod u+x ./embedded_base64

$ time ./embedded_base64
Hello World !

real  0m0.014s
user  0m0.008s
sys 0m0.004s

$ grep "Hello" ./embedded_base64
$

update:

this project (pyarmor) might also help:

https://pypi.org/project/pyarmor/

How do you stop MySQL on a Mac OS install?

Try

sudo <path to mysql>/support-files/mysql.server start
sudo <path to mysql>/support-files/mysql.server stop

Else try:

sudo /Library/StartupItems/MySQLCOM/MySQLCOM start
sudo /Library/StartupItems/MySQLCOM/MySQLCOM stop<br>
sudo /Library/StartupItems/MySQLCOM/MySQLCOM restart

However, I found that the second option only worked (OS X 10.6, MySQL 5.1.50) if the .plist has been loaded with:

sudo launchctl load -w /Library/LaunchDaemons/com.mysql.mysqld.plist

PS: I also found that I needed to unload the .plist to get an unrelated install of MAMP-MySQL to start / stop correctly. After running running this, MAMP-MySQL starts just fine:

sudo launchctl unload -w /Library/LaunchDaemons/com.mysql.mysqld.plist

Timing a command's execution in PowerShell

Use Measure-Command

Example

Measure-Command { <your command here> | Out-Host }

The pipe to Out-Host allows you to see the output of the command, which is otherwise consumed by Measure-Command.

(How) can I count the items in an enum?

I really do not see any way to really get to the number of values in an enumeration in C++. Any of the before mention solution work as long as you do not define the value of your enumerations if you define you value that you might run into situations where you either create arrays too big or too small

enum example{ test1 = -2, test2 = -1, test3 = 0, test4 = 1, test5 = 2 }

in this about examples the result would create a array of 3 items when you need an array of 5 items

enum example2{ test1 , test2 , test3 , test4 , test5 = 301 }

in this about examples the result would create a array of 301 items when you need an array of 5 items

The best way to solve this problem in the general case would be to iterate through your enumerations but that is not in the standard yet as far as I know

Getting a random value from a JavaScript array

This is similar to, but more general than, @Jacob Relkin's solution:

This is ES2015:

const randomChoice = arr => {
    const randIndex = Math.floor(Math.random() * arr.length);
    return arr[randIndex];
};

The code works by selecting a random number between 0 and the length of the array, then returning the item at that index.

How to use PHP's password_hash to hash and verify passwords

Using password_hash is the recommended way to store passwords. Don't separate them to DB and files.

Let's say we have the following input:

$password = $_POST['password'];

You first hash the password by doing this:

$hashed_password = password_hash($password, PASSWORD_DEFAULT);

Then see the output:

var_dump($hashed_password);

As you can see it's hashed. (I assume you did those steps).

Now you store this hashed password in your database, ensuring your password column is large enough to hold the hashed value (at least 60 characters or longer). When a user asks to log them in, you check the password input with this hash value in the database, by doing this:

// Query the database for username and password
// ...

if(password_verify($password, $hashed_password)) {
    // If the password inputs matched the hashed password in the database
    // Do something, you know... log them in.
} 

// Else, Redirect them back to the login page.

Official Reference

How do I import an existing Java keystore (.jks) file into a Java installation?

to load a KeyStore, you'll need to tell it the type of keystore it is (probably jceks), provide an inputstream, and a password. then, you can load it like so:

KeyStore ks  = KeyStore.getInstance(TYPE_OF_KEYSTORE);
ks.load(new FileInputStream(PATH_TO_KEYSTORE), PASSWORD);

this can throw a KeyStoreException, so you can surround in a try block if you like, or re-throw. Keep in mind a keystore can contain multiple keys, so you'll need to look up your key with an alias, here's an example with a symmetric key:

SecretKeyEntry entry = (KeyStore.SecretKeyEntry)ks.getEntry(SOME_ALIAS,new KeyStore.PasswordProtection(SOME_PASSWORD));
SecretKey someKey = entry.getSecretKey();

How can I make window.showmodaldialog work in chrome 37?

A very good, and working, javascript solution is provided here : https://github.com/niutech/showModalDialog

I personnally used it, works like before for other browser and it creates a new dialog for chrome browser.

Here is an example on how to use it :

function handleReturnValue(returnValue) {
    if (returnValue !== undefined) {
        // do what you want
    }
}

var myCallback = function (returnValue) { // callback for chrome usage
    handleReturnValue(returnValue);
};

var returnValue = window.showModalDialog('someUrl', 'someDialogTitle', 'someDialogParams', myCallback); 
handleReturnValue(returnValue); // for other browsers except Chrome

Disable the postback on an <ASP:LinkButton>

ASPX code:

<asp:LinkButton ID="someID" runat="server" Text="clicky"></asp:LinkButton>

Code behind:

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        someID.Attributes.Add("onClick", "return false;");
    }
}

What renders as HTML is:

<a onclick="return false;" id="someID" href="javascript:__doPostBack('someID','')">clicky</a>

In this case, what happens is the onclick functionality becomes your validator. If it is false, the "href" link is not executed; however, if it is true the href will get executed. This eliminates your post back.

How to detect running app using ADB command

You can use

adb shell ps | grep apps | awk '{print $9}'

to produce an output like:

com.google.process.gapps
com.google.android.apps.uploader
com.google.android.apps.plus
com.google.android.apps.maps
com.google.android.apps.maps:GoogleLocationService
com.google.android.apps.maps:FriendService
com.google.android.apps.maps:LocationFriendService

adb shell ps returns a list of all running processes on the android device, grep apps searches for any row with contains "apps", as you can see above they are all com.google.android.APPS. or GAPPS, awk extracts the 9th column which in this case is the package name.

To search for a particular package use

adb shell ps | grep PACKAGE.NAME.HERE | awk '{print $9}'

i.e adb shell ps | grep com.we7.player | awk '{print $9}'

If it is running the name will appear, if not there will be no result returned.

Rename specific column(s) in pandas

How do I rename a specific column in pandas?

From v0.24+, to rename one (or more) columns at a time,

If you need to rename ALL columns at once,

  • DataFrame.set_axis() method with axis=1. Pass a list-like sequence. Options are available for in-place modification as well.

rename with axis=1

df = pd.DataFrame('x', columns=['y', 'gdp', 'cap'], index=range(5))
df

   y gdp cap
0  x   x   x
1  x   x   x
2  x   x   x
3  x   x   x
4  x   x   x

With 0.21+, you can now specify an axis parameter with rename:

df.rename({'gdp':'log(gdp)'}, axis=1)
# df.rename({'gdp':'log(gdp)'}, axis='columns')
    
   y log(gdp) cap
0  x        x   x
1  x        x   x
2  x        x   x
3  x        x   x
4  x        x   x

(Note that rename is not in-place by default, so you will need to assign the result back.)

This addition has been made to improve consistency with the rest of the API. The new axis argument is analogous to the columns parameter—they do the same thing.

df.rename(columns={'gdp': 'log(gdp)'})

   y log(gdp) cap
0  x        x   x
1  x        x   x
2  x        x   x
3  x        x   x
4  x        x   x

rename also accepts a callback that is called once for each column.

df.rename(lambda x: x[0], axis=1)
# df.rename(lambda x: x[0], axis='columns')

   y  g  c
0  x  x  x
1  x  x  x
2  x  x  x
3  x  x  x
4  x  x  x

For this specific scenario, you would want to use

df.rename(lambda x: 'log(gdp)' if x == 'gdp' else x, axis=1)

Index.str.replace

Similar to replace method of strings in python, pandas Index and Series (object dtype only) define a ("vectorized") str.replace method for string and regex-based replacement.

df.columns = df.columns.str.replace('gdp', 'log(gdp)')
df
 
   y log(gdp) cap
0  x        x   x
1  x        x   x
2  x        x   x
3  x        x   x
4  x        x   x

The advantage of this over the other methods is that str.replace supports regex (enabled by default). See the docs for more information.


Passing a list to set_axis with axis=1

Call set_axis with a list of header(s). The list must be equal in length to the columns/index size. set_axis mutates the original DataFrame by default, but you can specify inplace=False to return a modified copy.

df.set_axis(['cap', 'log(gdp)', 'y'], axis=1, inplace=False)
# df.set_axis(['cap', 'log(gdp)', 'y'], axis='columns', inplace=False)

  cap log(gdp)  y
0   x        x  x
1   x        x  x
2   x        x  x
3   x        x  x
4   x        x  x

Note: In future releases, inplace will default to True.

Method Chaining
Why choose set_axis when we already have an efficient way of assigning columns with df.columns = ...? As shown by Ted Petrou in this answer set_axis is useful when trying to chain methods.

Compare

# new for pandas 0.21+
df.some_method1()
  .some_method2()
  .set_axis()
  .some_method3()

Versus

# old way
df1 = df.some_method1()
        .some_method2()
df1.columns = columns
df1.some_method3()

The former is more natural and free flowing syntax.

Python - Using regex to find multiple matches and print them out

Do not use regular expressions to parse HTML.

But if you ever need to find all regexp matches in a string, use the findall function.

import re
line = 'bla bla bla<form>Form 1</form> some text...<form>Form 2</form> more text?'
matches = re.findall('<form>(.*?)</form>', line, re.DOTALL)
print(matches)

# Output: ['Form 1', 'Form 2']

How to use ArgumentCaptor for stubbing?

Hypothetically, if search landed you on this question then you probably want this:

doReturn(someReturn).when(someObject).doSomething(argThat(argument -> argument.getName().equals("Bob")));

Why? Because like me you value time and you are not going to implement .equals just for the sake of the single test scenario.

And 99 % of tests fall apart with null returned from Mock and in a reasonable design you would avoid return null at all costs, use Optional or move to Kotlin. This implies that verify does not need to be used that often and ArgumentCaptors are just too tedious to write.

google maps v3 marker info window on mouseover

Here's an example: http://duncan99.wordpress.com/2011/10/08/google-maps-api-infowindows/

marker.addListener('mouseover', function() {
    infowindow.open(map, this);
});

// assuming you also want to hide the infowindow when user mouses-out
marker.addListener('mouseout', function() {
    infowindow.close();
});

Prevent BODY from scrolling when a modal is opened

If modal are 100% height/width "mouseenter/leave" will work to easily enable/disable scrolling. This really worked out for me:

var currentScroll=0;
function lockscroll(){
    $(window).scrollTop(currentScroll);
} 
$("#myModal").mouseenter(function(){
    currentScroll=$(window).scrollTop();
    $(window).bind('scroll',lockscroll); 
}).mouseleave(function(){
    currentScroll=$(window).scrollTop();
    $(window).unbind('scroll',lockscroll); 
});

Removing duplicates from a list of lists

Create a dictionary with tuple as the key, and print the keys.

  • create dictionary with tuple as key and index as value
  • print list of keys of dictionary

k = [[1, 2], [4], [5, 6, 2], [1, 2], [3], [4]]

dict_tuple = {tuple(item): index for index, item in enumerate(k)}

print [list(itm) for itm in dict_tuple.keys()]

# prints [[1, 2], [5, 6, 2], [3], [4]]

Cannot set property 'display' of undefined

document.getElementsByClassName('btn-pageMenu') delivers a nodeList. You should use: document.getElementsByClassName('btn-pageMenu')[0].style.display (if it's the first element from that list you want to change.

If you want to change style.display for all nodes loop through the list:

var elems = document.getElementsByClassName('btn-pageMenu');
for (var i=0;i<elems.length;i+=1){
  elems[i].style.display = 'block';
}

to be complete: if you use jquery it is as simple as:

?$('.btn-pageMenu').css('display'???????????????????????????,'block');??????

Django REST Framework: adding additional field to ModelSerializer

if you want read and write on your extra field, you can use a new custom serializer, that extends serializers.Serializer, and use it like this

class ExtraFieldSerializer(serializers.Serializer):
    def to_representation(self, instance): 
        # this would have the same as body as in a SerializerMethodField
        return 'my logic here'

    def to_internal_value(self, data):
        # This must return a dictionary that will be used to
        # update the caller's validation data, i.e. if the result
        # produced should just be set back into the field that this
        # serializer is set to, return the following:
        return {
          self.field_name: 'Any python object made with data: %s' % data
        }

class MyModelSerializer(serializers.ModelSerializer):
    my_extra_field = ExtraFieldSerializer(source='*')

    class Meta:
        model = MyModel
        fields = ['id', 'my_extra_field']

i use this in related nested fields with some custom logic

Does PHP have threading?

Just an update, its seem that PHP guys are working on supporting thread and its available now.

Here is the link to it: http://php.net/manual/en/book.pthreads.php

How to make grep only match if the entire line matches?

I'd prefer:

str="ABB.log"; grep -E "^${str}$" a.tmp

cheers

How to get the hours difference between two date objects?

Use the timestamp you get by calling valueOf on the date object:

var diff = date2.valueOf() - date1.valueOf();
var diffInHours = diff/1000/60/60; // Convert milliseconds to hours

How to edit my Excel dropdown list?

The answers above will work for changing the values.

If you want to change the number of cells in your list (e.g. I have a list called 'revisions' which has 4 items, I now need 7 items) you will find that you can't simply select your list and amend it on the sheet, So:

go to your 'Formulas' tab

choose "Name Manager"

a pop up box will show what is available for editing. Your list should be in it. Select your list and edit the range.

How to format date with hours, minutes and seconds when using jQuery UI Datepicker?

_x000D_
_x000D_
$(function() {_x000D_
    $('#datepicker').datepicker({ dateFormat: 'yy-d-m ' }).val();_x000D_
});
_x000D_
<html>_x000D_
<head>_x000D_
  <link rel="stylesheet" href="http://code.jquery.com/ui/1.9.2/themes/base/jquery-ui.css">_x000D_
  <title>snippet</title>_x000D_
</head>_x000D_
<body>_x000D_
_x000D_
  <input type="text" id="datepicker">_x000D_
_x000D_
  <script src="https://code.jquery.com/jquery-1.12.4.min.js"></script>_x000D_
  <script src="https://code.jquery.com/ui/1.9.2/jquery-ui.min.js"></script>
_x000D_
_x000D_
_x000D_

How to access Spring context in jUnit tests annotated with @RunWith and @ContextConfiguration?

It's possible to inject instance of ApplicationContext class by using SpringClassRule and SpringMethodRule rules. It might be very handy if you would like to use another non-Spring runners. Here's an example:

@ContextConfiguration(classes = BeanConfiguration.class)
public static class SpringRuleUsage {

    @ClassRule
    public static final SpringClassRule springClassRule = new SpringClassRule();

    @Rule
    public final SpringMethodRule springMethodRule = new SpringMethodRule();

    @Autowired
    private ApplicationContext context;

    @Test
    public void shouldInjectContext() {
    }
}

How to check if a given directory exists in Ruby

You could use Kernel#test:

test ?d, 'some directory'

it gets it's origins from https://ss64.com/bash/test.html you will notice bash test has this flag -d to test if a directory exists -d file True if file is a Directory. [[ -d demofile ]]

Integrating the ZXing library directly into my Android application

Since some of the answers are outdated, I would like to provide my own -

To integrate ZXing library into your Android app as suggested by their Wiki, you need to add 2 Java files to your project:

Then in Android Studio add the following line to build.gradle file:

dependencies {
    ....
    compile 'com.google.zxing:core:3.2.1'
}

Or if still using Eclipse with ADT-plugin add core.jar file to the libs subdirectory of your project (here fullscreen Windows and fullscreen Mac):

Windows screenshot

Finally add this code to your MainActivity.java:

public void scanQRCode(View v) {
    IntentIntegrator integrator = new IntentIntegrator(MainActivity.this);
    integrator.initiateScan(IntentIntegrator.QR_CODE_TYPES);
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
    IntentResult result = 
        IntentIntegrator.parseActivityResult(requestCode, resultCode, intent);
    if (result != null) {
        String contents = result.getContents();
        if (contents != null) {
            showDialog(R.string.result_succeeded, result.toString());
        } else {
            showDialog(R.string.result_failed,
                getString(R.string.result_failed_why));
        }
    }
}

private void showDialog(int title, CharSequence message) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle(title);
    builder.setMessage(message);
    builder.setPositiveButton(R.string.ok_button, null);
    builder.show();
}

The resulting app will ask to install and start Barcode Scanner app by ZXing (which will return to your app automatically after scanning):

Barcode Scanner app

Additionally, if you would like to build and run the ZXing Test app as inspiration for your own app:

ZXing Test app

Then you need 4 Java files from GitHub:

  • BenchmarkActivity.java
  • BenchmarkAsyncTask.java
  • BenchmarkItem.java
  • ZXingTestActivity.java

And 3 Jar files from Maven repository:

  • core.jar
  • android-core.jar
  • android-integration.jar

(You can build the Jar files yourself with mvn package - if your check out ZXing from GitHub and install ant and maven tools at your computer).

Note: if your project does not recognize the Jar files, you might need to up the Java version in the Project Properties:

properties screenshot

How do I trim whitespace?

For whitespace on both sides use str.strip:

s = "  \t a string example\t  "
s = s.strip()

For whitespace on the right side use rstrip:

s = s.rstrip()

For whitespace on the left side lstrip:

s = s.lstrip()

As thedz points out, you can provide an argument to strip arbitrary characters to any of these functions like this:

s = s.strip(' \t\n\r')

This will strip any space, \t, \n, or \r characters from the left-hand side, right-hand side, or both sides of the string.

The examples above only remove strings from the left-hand and right-hand sides of strings. If you want to also remove characters from the middle of a string, try re.sub:

import re
print(re.sub('[\s+]', '', s))

That should print out:

astringexample

@JsonProperty annotation on field as well as getter/setter

In addition to existing good answers, note that Jackson 1.9 improved handling by adding "property unification", meaning that ALL annotations from difference parts of a logical property are combined, using (hopefully) intuitive precedence.

In Jackson 1.8 and prior, only field and getter annotations were used when determining what and how to serialize (writing JSON); and only and setter annotations for deserialization (reading JSON). This sometimes required addition of "extra" annotations, like annotating both getter and setter.

With Jackson 1.9 and above these extra annotations are NOT needed. It is still possible to add those; and if different names are used, one can create "split" properties (serializing using one name, deserializing using other): this is occasionally useful for sort of renaming.

How to make a drop down list in yii2?

Maybe I'm wrong but I think that SQL query from view is a bad idea

This is my way

In controller

$model = new SomeModel();
$items=ArrayHelper::map(TableName::find()->all(),'id','name');


return $this->render('view',['model'=>$model, 'items'=>$items])

And in View

<?= Html::activeDropDownList($model, 'item_id',$items) ?>

Or using ActiveForm

<?php $form = ActiveForm::begin(); ?>
 <?= $form->field($model, 'item_id')->dropDownList($items) ?>
<?php ActiveForm::end(); ?>

What is the equivalent of the C# 'var' keyword in Java?

JEP - JDK Enhancement-Proposal

http://openjdk.java.net/jeps/286

JEP 286: Local-Variable Type Inference

Author Brian Goetz

// Goals:
var list = new ArrayList<String>();  // infers ArrayList<String>
var stream = list.stream();          // infers Stream<String>

SQL Server function to return minimum date (January 1, 1753)

It's not January 1, 1753 but select cast('' as datetime) wich reveals: 1900-01-01 00:00:00.000 gives the default value by SQL server. (Looks more uninitialized to me anyway)

Load local JSON file into variable

For ES6/ES2015 you can import directly like:

// example.json
{
    "name": "testing"
}


// ES6/ES2015
// app.js
import * as data from './example.json';
const {name} = data;
console.log(name); // output 'testing'

If you use Typescript, you may declare json module like:

// tying.d.ts
declare module "*.json" {
    const value: any;
    export default value;
}

Since Typescript 2.9+ you can add --resolveJsonModule compilerOptions in tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
     ...
    "resolveJsonModule": true,
     ...
  },
  ...
}

Is there a way to access the "previous row" value in a SELECT statement?

LEFT JOIN the table to itself, with the join condition worked out so the row matched in the joined version of the table is one row previous, for your particular definition of "previous".

Update: At first I was thinking you would want to keep all rows, with NULLs for the condition where there was no previous row. Reading it again you just want that rows culled, so you should an inner join rather than a left join.


Update:

Newer versions of Sql Server also have the LAG and LEAD Windowing functions that can be used for this, too.

Pip Install not installing into correct directory?

Virtualenv is your friend

Even if you want to add a package to your primary install, it's still best to do it in a virtual environment first, to ensure compatibility with your other packages. However, if you get familiar with virtualenv, you'll probably find there's really no reason to install anything in your base install.

Clone contents of a GitHub repository (without the folder itself)

You can specify the destination directory as second parameter of the git clone command, so you can do:

git clone <remote> .

This will clone the repository directly in the current local directory.

Special characters like @ and & in cURL POST data

Double quote (" ") the entire URL .It works.

curl "http://www.mysite.com?name=john&passwd=@31&3*J"

Mysql: Select rows from a table that are not in another

You need to do the subselect based on a column name, not *.

For example, if you had an id field common to both tables, you could do:

SELECT * FROM Table1 WHERE id NOT IN (SELECT id FROM Table2)

Refer to the MySQL subquery syntax for more examples.

Get current date in DD-Mon-YYY format in JavaScript/Jquery

I've made a custom date string format function, you can use that.

var  getDateString = function(date, format) {
        var months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
        getPaddedComp = function(comp) {
            return ((parseInt(comp) < 10) ? ('0' + comp) : comp)
        },
        formattedDate = format,
        o = {
            "y+": date.getFullYear(), // year
            "M+": months[date.getMonth()], //month
            "d+": getPaddedComp(date.getDate()), //day
            "h+": getPaddedComp((date.getHours() > 12) ? date.getHours() % 12 : date.getHours()), //hour
             "H+": getPaddedComp(date.getHours()), //hour
            "m+": getPaddedComp(date.getMinutes()), //minute
            "s+": getPaddedComp(date.getSeconds()), //second
            "S+": getPaddedComp(date.getMilliseconds()), //millisecond,
            "b+": (date.getHours() >= 12) ? 'PM' : 'AM'
        };

        for (var k in o) {
            if (new RegExp("(" + k + ")").test(format)) {
                formattedDate = formattedDate.replace(RegExp.$1, o[k]);
            }
        }
        return formattedDate;
    };

And now suppose you've :-

    var date = "2014-07-12 10:54:11";

So to format this date you write:-

var formattedDate = getDateString(new Date(date), "d-M-y")

LaTeX table positioning

You may want to add this to your preamble, and adjust the values as necessary:

 %------------begin Float Adjustment
%two column float page must be 90% full
\renewcommand\dblfloatpagefraction{.90}
%two column top float can cover up to 80% of page
\renewcommand\dbltopfraction{.80}
%float page must be 90% full
\renewcommand\floatpagefraction{.90}
%top float can cover up to 80% of page
\renewcommand\topfraction{.80}
%bottom float can cover up to 80% of page
\renewcommand\bottomfraction{.80}
%at least 10% of a normal page must contain text
\renewcommand\textfraction{.1}
%separation between floats and text
\setlength\dbltextfloatsep{9pt plus 5pt minus 3pt }
%separation between two column floats and text
\setlength\textfloatsep{4pt plus 2pt minus 1.5pt}

Particularly, the \floatpagefraction may be of interest.

How to cast from List<Double> to double[] in Java?

As per your question,

List<Double> frameList =  new ArrayList<Double>();
  1. First you have to convert List<Double> to Double[] by using

    Double[] array = frameList.toArray(new Double[frameList.size()]);
    
  2. Next you can convert Double[] to double[] using

    double[] doubleArray = ArrayUtils.toPrimitive(array);
    

You can directly use it in one line:

double[] array = ArrayUtils.toPrimitive(frameList.toArray(new Double[frameList.size()]));

How to save a list to a file and read it as a list type?

I decided I didn't want to use a pickle because I wanted to be able to open the text file and change its contents easily during testing. Therefore, I did this:

score = [1,2,3,4,5]

with open("file.txt", "w") as f:
    for s in score:
        f.write(str(s) +"\n")
score = []
with open("file.txt", "r") as f:
  for line in f:
    score.append(int(line.strip()))

So the items in the file are read as integers, despite being stored to the file as strings.

How can I represent an 'Enum' in Python?

Following the Java like enum implementation proposed by Aaron Maenpaa, I came out with the following. The idea was to make it generic and parseable.

class Enum:
    #'''
    #Java like implementation for enums.
    #
    #Usage:
    #class Tool(Enum): name = 'Tool'
    #Tool.DRILL = Tool.register('drill')
    #Tool.HAMMER = Tool.register('hammer')
    #Tool.WRENCH = Tool.register('wrench')
    #'''

    name = 'Enum'    # Enum name
    _reg = dict([])   # Enum registered values

    @classmethod
    def register(cls, value):
        #'''
        #Registers a new value in this enum.
        #
        #@param value: New enum value.
        #
        #@return: New value wrapper instance.
        #'''
        inst = cls(value)
        cls._reg[value] = inst
        return inst

    @classmethod
    def parse(cls, value):
        #'''
        #Parses a value, returning the enum instance.
        #
        #@param value: Enum value.
        #
        #@return: Value corresp instance.        
        #'''
        return cls._reg.get(value)    

    def __init__(self, value):
        #'''
        #Constructor (only for internal use).
        #'''
        self.value = value

    def __str__(self):
        #'''
        #str() overload.
        #'''
        return self.value

    def __repr__(self):
        #'''
        #repr() overload.
        #'''
        return "<" + self.name + ": " + self.value + ">"

Disabling Chrome Autofill

Like Dvd Franco said, for me only puting automplete='off' in all fields it worked. So I put this jquery rules in $(document).ready(); function on my main .js file

$('form.no_autofill').attr('autocomplete','off');
$('.no_autofill input').attr('autocomplete','off');

Saving ssh key fails

I struggled with the same problem for a while just now (using Mac). Here is what I did and it finally worked:
(1) Confirm the .ssh directory exists:

#show all files including hidden
ls -a 

(2) Accept all default values by just pressing enter at the prompt

Enter file in which to save the key (/Users/username/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 

You should get a message :

Your identification has been saved in /Users/username/.ssh/id_rsa.
Your public key has been saved in /Users/username/.ssh/id_rsa.pub.
The key fingerprint is:
BZA156:HVhsjsdhfdkjfdfhdX+BundfOytLezXvbx831/s [email protected]
The key's randomart image is:XXXXX

PS If you are configuring git for rails, do the following (source):

git config --global color.ui true
git config --global user.name "yourusername"
git config --global user.email "[email protected]"
ssh-keygen -t rsa -C "[email protected]" 

(then accept all defaults by pressing enter)

How to check if IsNumeric

You could write an extension method:

public static class Extension
{
    public static bool IsNumeric(this string s)
    {
        float output;
        return float.TryParse(s, out output);
    }
}

java.lang.IllegalStateException: Only fullscreen opaque activities can request orientation

If you have to use setRequestedOrientation(), there is no way but sacrifice the windowIsTranslucent attribute on Android 8.0

values\styles.xml for api level 25- (<8.0)

<style name="Base.Theme.DesignDemo" parent="Base.Theme.AppCompat.Light">
        ...
        <item name="android:windowIsTranslucent">true</item>
        ...
    </style>

values-v26\styles.xml for api level 26 (=8.0)

<style name="Base.Theme.DesignDemo" parent="Base.Theme.AppCompat.Light">
    ...
    <!-- android 8.0(api26),Only fullscreen opaque activities can request orientation -->
    <item name="android:windowIsTranslucent">false</item>
    ...
</style>

values-v27\styles.xml for api level 27+ (>8.0)

<style name="Base.Theme.DesignDemo" parent="Base.Theme.AppCompat.Light">
    ...
    <item name="android:windowIsTranslucent">true</item>
    ...
</style>

Can I make a <button> not submit a form?

The default value for the type attribute of button elements is "submit". Set it to type="button" to produce a button that doesn't submit the form.

<button type="button">Submit</button>

In the words of the HTML Standard: "Does nothing."

How to print last two columns using awk

You can make use of variable NF which is set to the total number of fields in the input record:

awk '{print $(NF-1),"\t",$NF}' file

this assumes that you have at least 2 fields.

Command to run a .bat file

Can refer to here: https://ss64.com/nt/start.html

start "" /D F:\- Big Packets -\kitterengine\Common\ /W Template.bat

Force an Android activity to always use landscape mode

Doing it in code is is IMO wrong and even more so if you put it into the onCreate. Do it in the manifest and the "system" knows the orientation from the startup of the app. And this type of meta or top level "guidance" SHOULD be in the manifest. If you want to prove it to yourself set a break in the Activity's onCreate. If you do it in code there it will be called twice : it starts up in Portrait mode then is switched to Landscape. This does not happen if you do it in the manifest.

Newtonsoft JSON Deserialize

As per the Newtonsoft Documentation you can also deserialize to an anonymous object like this:

var definition = new { Name = "" };

string json1 = @"{'Name':'James'}";
var customer1 = JsonConvert.DeserializeAnonymousType(json1, definition);

Console.WriteLine(customer1.Name);
// James

Transform only one axis to log10 scale with ggplot2

I think I got it at last by doing some manual transformations with the data before visualization:

d <- diamonds
# computing logarithm of prices
d$price <- log10(d$price)

And work out a formatter to later compute 'back' the logarithmic data:

formatBack <- function(x) 10^x 
# or with special formatter (here: "dollar")
formatBack <- function(x) paste(round(10^x, 2), "$", sep=' ') 

And draw the plot with given formatter:

m <- ggplot(d, aes(y = price, x = color))
m + geom_boxplot() + scale_y_continuous(formatter='formatBack')

alt text

Sorry to the community to bother you with a question I could have solved before! The funny part is: I was working hard to make this plot work a month ago but did not succeed. After asking here, I got it.

Anyway, thanks to @DWin for motivation!

Importing data from a JSON file into R

First install the rjson package:

install.packages("rjson")

Then:

library("rjson")
json_file <- "http://api.worldbank.org/country?per_page=10&region=OED&lendingtype=LNX&format=json"
json_data <- fromJSON(paste(readLines(json_file), collapse=""))

Update: since version 0.2.1

json_data <- fromJSON(file=json_file)

Should a function have only one return statement?

The only important question is "How is the code simpler, better readable, easier to understand?" If it is simpler with multiple returns, then use them.

LaTeX Optional Arguments

The general idea behind creating "optional arguments" is to first define an intermediate command that scans ahead to detect what characters are coming up next in the token stream and then inserts the relevant macros to process the argument(s) coming up as appropriate. This can be quite tedious (although not difficult) using generic TeX programming. LaTeX's \@ifnextchar is quite useful for such things.

The best answer for your question is to use the new xparse package. It is part of the LaTeX3 programming suite and contains extensive features for defining commands with quite arbitrary optional arguments.

In your example you have a \sec macro that either takes one or two braced arguments. This would be implemented using xparse with the following:

\documentclass{article}
\usepackage{xparse}
\begin{document}
\DeclareDocumentCommand\sec{ m g }{%
    {#1%
        \IfNoValueF {#2} { and #2}%
    }%
}
(\sec{Hello})
(\sec{Hello}{Hi})
\end{document}

The argument { m g } defines the arguments of \sec; m means "mandatory argument" and g is "optional braced argument". \IfNoValue(T)(F) can then be used to check whether the second argument was indeed present or not. See the documentation for the other types of optional arguments that are allowed.

Why use a READ UNCOMMITTED isolation level?

When is it ok to use READ UNCOMMITTED?

Rule of thumb

Good: Big aggregate reports showing constantly changing totals.

Risky: Nearly everything else.

The good news is that the majority of read-only reports fall in that Good category.

More detail...

Ok to use it:

  • Nearly all user-facing aggregate reports for current, non-static data e.g. Year to date sales. It risks a margin of error (maybe < 0.1%) which is much lower than other uncertainty factors such as inputting error or just the randomness of when exactly data gets recorded minute to minute.

That covers probably the majority of what an Business Intelligence department would do in, say, SSRS. The exception of course, is anything with $ signs in front of it. Many people account for money with much more zeal than applied to the related core metrics required to service the customer and generate that money. (I blame accountants).

When risky

  • Any report that goes down to the detail level. If that detail is required it usually implies that every row will be relevant to a decision. In fact, if you can't pull a small subset without blocking it might be for the good reason that it's being currently edited.

  • Historical data. It rarely makes a practical difference but whereas users understand constantly changing data can't be perfect, they don't feel the same about static data. Dirty reads won't hurt here but double reads can occasionally be. Seeing as you shouldn't have blocks on static data anyway, why risk it?

  • Nearly anything that feeds an application which also has write capabilities.

When even the OK scenario is not OK.

  • Are any applications or update processes making use of big single transactions? Ones which remove then re-insert a lot of records you're reporting on? In that case you really can't use NOLOCK on those tables for anything.

Show hide fragment in android

Don't mess with the visibility flags of the container - FragmentTransaction.hide/show does that internally for you.

So the correct way to do this is:

FragmentManager fm = getFragmentManager();
fm.beginTransaction()
          .setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out)
          .show(somefrag)
          .commit();

OR if you are using android.support.v4.app.Fragment

 FragmentManager fm = getSupportFragmentManager();
 fm.beginTransaction()
          .setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out)
          .show(somefrag)
          .commit();

Remove duplicate rows in MySQL

I keep visiting this page anytime I google "remove duplicates form mysql" but for my theIGNORE solutions don't work because I have an InnoDB mysql tables

this code works better anytime

CREATE TABLE tableToclean_temp LIKE tableToclean;
ALTER TABLE tableToclean_temp ADD UNIQUE INDEX (fontsinuse_id);
INSERT IGNORE INTO tableToclean_temp SELECT * FROM tableToclean;
DROP TABLE tableToclean;
RENAME TABLE tableToclean_temp TO tableToclean;

tableToclean = the name of the table you need to clean

tableToclean_temp = a temporary table created and deleted