Datanode process not running in Hadoop
- Stop the dfs and yarn first.
- Remove the datanode and namenode directories as specified in the core-site.xml file.
- Re-create the directories.
Then re-start the dfs and the yarn as follows.
start-dfs.sh
start-yarn.sh
mr-jobhistory-daemon.sh start historyserver
Hope this works fine.
Java and HTTPS url connection without downloading certificate
But why don't I have to install a certificate locally for the site?
Well the code that you are using is explicitly designed to accept the certificate without doing any checks whatsoever. This is not good practice ... but if that is what you want to do, then (obviously) there is no need to install a certificate that your code is explicitly ignoring.
Shouldn't I have to install a certificate locally and load it for this program or is it downloaded behind the covers?
No, and no. See above.
Is the traffic between the client to the remote site still encrypted in transmission?
Yes it is. However, the problem is that since you have told it to trust the server's certificate without doing any checks, you don't know if you are talking to the real server, or to some other site that is pretending to be the real server. Whether this is a problem depends on the circumstances.
If we used the browser as an example, typically a browser doesn't ask the user to explicitly install a certificate for each ssl site visited.
The browser has a set of trusted root certificates pre-installed. Most times, when you visit an "https" site, the browser can verify that the site's certificate is (ultimately, via the certificate chain) secured by one of those trusted certs. If the browser doesn't recognize the cert at the start of the chain as being a trusted cert (or if the certificates are out of date or otherwise invalid / inappropriate), then it will display a warning.
Java works the same way. The JVM's keystore has a set of trusted certificates, and the same process is used to check the certificate is secured by a trusted certificate.
Does the java https client api support some type of mechanism to download certificate information automatically?
No. Allowing applications to download certificates from random places, and install them (as trusted) in the system keystore would be a security hole.
How to execute only one test spec with angular-cli
This is working for me in Angular 7. It is based on the --main option of the ng command. I am not sure if this option is undocumented and possibly subject to change, but it works for me. I put a line in my package.json file in scripts section. There using the --main option of with the ng test command, I specify the path to the .spec.ts file I want to execute. For example
"test 1": "ng test --main E:/WebRxAngularClient/src/app/test/shared/my-date-utils.spec.ts",
You can run the script as you run any such script. I run it in Webstorm by clicking on "test 1" in the npm section.
How to use sed/grep to extract text between two words?
All the above solutions have deficiencies where the last search string is repeated elsewhere in the string. I found it best to write a bash function.
function str_str {
local str
str="${1#*${2}}"
str="${str%%$3*}"
echo -n "$str"
}
# test it ...
mystr="this is a string"
str_str "$mystr" "this " " string"
Mapping over values in a python dictionary
You can do this in-place, rather than create a new dict, which may be preferable for large dictionaries (if you do not need a copy).
def mutate_dict(f,d):
for k, v in d.iteritems():
d[k] = f(v)
my_dictionary = {'a':1, 'b':2}
mutate_dict(lambda x: x+1, my_dictionary)
results in my_dictionary
containing:
{'a': 2, 'b': 3}
Aggregate a dataframe on a given column and display another column
Here is a solution using the plyr
package.
The following line of code essentially tells ddply
to first group your data by Group, and then within each group returns a subset where the Score equals the maximum score in that group.
library(plyr)
ddply(data, .(Group), function(x)x[x$Score==max(x$Score), ])
Group Score Info
1 1 3 c
2 2 4 d
And, as @SachaEpskamp points out, this can be further simplified to:
ddply(df, .(Group), function(x)x[which.max(x$Score), ])
(which also has the advantage that which.max
will return multiple max lines, if there are any).
How to load a model from an HDF5 file in Keras?
See the following sample code on how to Build a basic Keras Neural Net Model, save Model (JSON) & Weights (HDF5) and load them:
# create model
model = Sequential()
model.add(Dense(X.shape[1], input_dim=X.shape[1], activation='relu')) #Input Layer
model.add(Dense(X.shape[1], activation='relu')) #Hidden Layer
model.add(Dense(output_dim, activation='softmax')) #Output Layer
# Compile & Fit model
model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
model.fit(X,Y,nb_epoch=5,batch_size=100,verbose=1)
# serialize model to JSON
model_json = model.to_json()
with open("Data/model.json", "w") as json_file:
json_file.write(simplejson.dumps(simplejson.loads(model_json), indent=4))
# serialize weights to HDF5
model.save_weights("Data/model.h5")
print("Saved model to disk")
# load json and create model
json_file = open('Data/model.json', 'r')
loaded_model_json = json_file.read()
json_file.close()
loaded_model = model_from_json(loaded_model_json)
# load weights into new model
loaded_model.load_weights("Data/model.h5")
print("Loaded model from disk")
# evaluate loaded model on test data
# Define X_test & Y_test data first
loaded_model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
score = loaded_model.evaluate(X_test, Y_test, verbose=0)
print ("%s: %.2f%%" % (loaded_model.metrics_names[1], score[1]*100))
PHP - SSL certificate error: unable to get local issuer certificate
I tried this it works
open
vendor\guzzlehttp\guzzle\src\Handler\CurlFactory.php
and change this
$conf[CURLOPT_SSL_VERIFYHOST] = 2;
`enter code here`$conf[CURLOPT_SSL_VERIFYPEER] = true;
to this
$conf[CURLOPT_SSL_VERIFYHOST] = 0;
$conf[CURLOPT_SSL_VERIFYPEER] = FALSE;
Mockito - NullpointerException when stubbing Method
faced the same issue, the solution that worked for me:
Instead of mocking the service interface, I used @InjectMocks to mock the service implementation:
@InjectMocks
private exampleServiceImpl exampleServiceMock;
instead of :
@Mock
private exampleService exampleServiceMock;
How to add elements to an empty array in PHP?
When one wants elements to be added with zero-based element indexing, I guess this will work as well:
// adding elements to an array with zero-based index
$matrix= array();
$matrix[count($matrix)]= 'element 1';
$matrix[count($matrix)]= 'element 2';
...
$matrix[count($matrix)]= 'element N';
selected value get from db into dropdown select box option using php mysql error
BEST code and simple
<select id="example-getting-started" multiple="multiple" name="category">
<?php
$query = "select * from mine";
$results = mysql_query($query);
while ($rows = mysql_fetch_assoc(@$results)){
?>
<option value="<?php echo $rows['category'];?>"><?php echo $rows['category'];?></option>
<?php
}
?>
</select>
Update elements in a JSONObject
Hello I can suggest you universal method. use recursion.
public static JSONObject function(JSONObject obj, String keyMain,String valueMain, String newValue) throws Exception {
// We need to know keys of Jsonobject
JSONObject json = new JSONObject()
Iterator iterator = obj.keys();
String key = null;
while (iterator.hasNext()) {
key = (String) iterator.next();
// if object is just string we change value in key
if ((obj.optJSONArray(key)==null) && (obj.optJSONObject(key)==null)) {
if ((key.equals(keyMain)) && (obj.get(key).toString().equals(valueMain))) {
// put new value
obj.put(key, newValue);
return obj;
}
}
// if it's jsonobject
if (obj.optJSONObject(key) != null) {
function(obj.getJSONObject(key), keyMain, valueMain, newValue);
}
// if it's jsonarray
if (obj.optJSONArray(key) != null) {
JSONArray jArray = obj.getJSONArray(key);
for (int i=0;i<jArray.length();i++) {
function(jArray.getJSONObject(i), keyMain, valueMain, newValue);
}
}
}
return obj;
}
It should work. If you have questions, go ahead.. I'm ready.
Android Color Picker
You can use the following code, it will give you same look as http://code.google.com/p/color-picker-view/
public class ColorPickerDialog extends Dialog {
public interface OnColorChangedListener {
void colorChanged(String key, int color);
}
private OnColorChangedListener mListener;
private int mInitialColor, mDefaultColor;
private String mKey;
private static class ColorPickerView extends View {
private Paint mPaint;
private float mCurrentHue = 0;
private int mCurrentX = 0, mCurrentY = 0;
private int mCurrentColor, mDefaultColor;
private final int[] mHueBarColors = new int[258];
private int[] mMainColors = new int[65536];
private OnColorChangedListener mListener;
ColorPickerView(Context c, OnColorChangedListener l, int color,
int defaultColor) {
super(c);
mListener = l;
mDefaultColor = defaultColor;
// Get the current hue from the current color and update the main
// color field
float[] hsv = new float[3];
Color.colorToHSV(color, hsv);
mCurrentHue = hsv[0];
updateMainColors();
mCurrentColor = color;
// Initialize the colors of the hue slider bar
int index = 0;
for (float i = 0; i < 256; i += 256 / 42) // Red (#f00) to pink
// (#f0f)
{
mHueBarColors[index] = Color.rgb(255, 0, (int) i);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) // Pink (#f0f) to blue
// (#00f)
{
mHueBarColors[index] = Color.rgb(255 - (int) i, 0, 255);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) // Blue (#00f) to light
// blue (#0ff)
{
mHueBarColors[index] = Color.rgb(0, (int) i, 255);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) // Light blue (#0ff) to
// green (#0f0)
{
mHueBarColors[index] = Color.rgb(0, 255, 255 - (int) i);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) // Green (#0f0) to yellow
// (#ff0)
{
mHueBarColors[index] = Color.rgb((int) i, 255, 0);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) // Yellow (#ff0) to red
// (#f00)
{
mHueBarColors[index] = Color.rgb(255, 255 - (int) i, 0);
index++;
}
// Initializes the Paint that will draw the View
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setTextAlign(Paint.Align.CENTER);
mPaint.setTextSize(12);
}
// Get the current selected color from the hue bar
private int getCurrentMainColor() {
int translatedHue = 255 - (int) (mCurrentHue * 255 / 360);
int index = 0;
for (float i = 0; i < 256; i += 256 / 42) {
if (index == translatedHue)
return Color.rgb(255, 0, (int) i);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) {
if (index == translatedHue)
return Color.rgb(255 - (int) i, 0, 255);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) {
if (index == translatedHue)
return Color.rgb(0, (int) i, 255);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) {
if (index == translatedHue)
return Color.rgb(0, 255, 255 - (int) i);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) {
if (index == translatedHue)
return Color.rgb((int) i, 255, 0);
index++;
}
for (float i = 0; i < 256; i += 256 / 42) {
if (index == translatedHue)
return Color.rgb(255, 255 - (int) i, 0);
index++;
}
return Color.RED;
}
// Update the main field colors depending on the current selected hue
private void updateMainColors() {
int mainColor = getCurrentMainColor();
int index = 0;
int[] topColors = new int[256];
for (int y = 0; y < 256; y++) {
for (int x = 0; x < 256; x++) {
if (y == 0) {
mMainColors[index] = Color.rgb(
255 - (255 - Color.red(mainColor)) * x / 255,
255 - (255 - Color.green(mainColor)) * x / 255,
255 - (255 - Color.blue(mainColor)) * x / 255);
topColors[x] = mMainColors[index];
} else
mMainColors[index] = Color.rgb(
(255 - y) * Color.red(topColors[x]) / 255,
(255 - y) * Color.green(topColors[x]) / 255,
(255 - y) * Color.blue(topColors[x]) / 255);
index++;
}
}
}
@Override
protected void onDraw(Canvas canvas) {
int translatedHue = 255 - (int) (mCurrentHue * 255 / 360);
// Display all the colors of the hue bar with lines
for (int x = 0; x < 256; x++) {
// If this is not the current selected hue, display the actual
// color
if (translatedHue != x) {
mPaint.setColor(mHueBarColors[x]);
mPaint.setStrokeWidth(1);
} else // else display a slightly larger black line
{
mPaint.setColor(Color.BLACK);
mPaint.setStrokeWidth(3);
}
canvas.drawLine(x + 10, 0, x + 10, 40, mPaint);
// canvas.drawLine(0, x+10, 40, x+10, mPaint);
}
// Display the main field colors using LinearGradient
for (int x = 0; x < 256; x++) {
int[] colors = new int[2];
colors[0] = mMainColors[x];
colors[1] = Color.BLACK;
Shader shader = new LinearGradient(0, 50, 0, 306, colors, null,
Shader.TileMode.REPEAT);
mPaint.setShader(shader);
canvas.drawLine(x + 10, 50, x + 10, 306, mPaint);
}
mPaint.setShader(null);
// Display the circle around the currently selected color in the
// main field
if (mCurrentX != 0 && mCurrentY != 0) {
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setColor(Color.BLACK);
canvas.drawCircle(mCurrentX, mCurrentY, 10, mPaint);
}
// Draw a 'button' with the currently selected color
mPaint.setStyle(Paint.Style.FILL);
mPaint.setColor(mCurrentColor);
canvas.drawRect(10, 316, 138, 356, mPaint);
// Set the text color according to the brightness of the color
if (Color.red(mCurrentColor) + Color.green(mCurrentColor)
+ Color.blue(mCurrentColor) < 384)
mPaint.setColor(Color.WHITE);
else
mPaint.setColor(Color.BLACK);
canvas.drawText(
getResources()
.getString(R.string.settings_bg_color_confirm), 74,
340, mPaint);
// Draw a 'button' with the default color
mPaint.setStyle(Paint.Style.FILL);
mPaint.setColor(mDefaultColor);
canvas.drawRect(138, 316, 266, 356, mPaint);
// Set the text color according to the brightness of the color
if (Color.red(mDefaultColor) + Color.green(mDefaultColor)
+ Color.blue(mDefaultColor) < 384)
mPaint.setColor(Color.WHITE);
else
mPaint.setColor(Color.BLACK);
canvas.drawText(
getResources().getString(
R.string.settings_default_color_confirm), 202, 340,
mPaint);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(276, 366);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() != MotionEvent.ACTION_DOWN)
return true;
float x = event.getX();
float y = event.getY();
// If the touch event is located in the hue bar
if (x > 10 && x < 266 && y > 0 && y < 40) {
// Update the main field colors
mCurrentHue = (255 - x) * 360 / 255;
updateMainColors();
// Update the current selected color
int transX = mCurrentX - 10;
int transY = mCurrentY - 60;
int index = 256 * (transY - 1) + transX;
if (index > 0 && index < mMainColors.length)
mCurrentColor = mMainColors[256 * (transY - 1) + transX];
// Force the redraw of the dialog
invalidate();
}
// If the touch event is located in the main field
if (x > 10 && x < 266 && y > 50 && y < 306) {
mCurrentX = (int) x;
mCurrentY = (int) y;
int transX = mCurrentX - 10;
int transY = mCurrentY - 60;
int index = 256 * (transY - 1) + transX;
if (index > 0 && index < mMainColors.length) {
// Update the current color
mCurrentColor = mMainColors[index];
// Force the redraw of the dialog
invalidate();
}
}
// If the touch event is located in the left button, notify the
// listener with the current color
if (x > 10 && x < 138 && y > 316 && y < 356)
mListener.colorChanged("", mCurrentColor);
// If the touch event is located in the right button, notify the
// listener with the default color
if (x > 138 && x < 266 && y > 316 && y < 356)
mListener.colorChanged("", mDefaultColor);
return true;
}
}
public ColorPickerDialog(Context context, OnColorChangedListener listener,
String key, int initialColor, int defaultColor) {
super(context);
mListener = listener;
mKey = key;
mInitialColor = initialColor;
mDefaultColor = defaultColor;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
OnColorChangedListener l = new OnColorChangedListener() {
public void colorChanged(String key, int color) {
mListener.colorChanged(mKey, color);
dismiss();
}
};
setContentView(new ColorPickerView(getContext(), l, mInitialColor,
mDefaultColor));
setTitle(R.string.settings_bg_color_dialog);
}
}
How to generate random colors in matplotlib?
Since the question is How to generate random colors in matplotlib?
and as I was searching for an answer concerning pie plots
, I think it is worth to put an answer here (for pies
)
import numpy as np
from random import sample
import matplotlib.pyplot as plt
import matplotlib.colors as pltc
all_colors = [k for k,v in pltc.cnames.items()]
fracs = np.array([600, 179, 154, 139, 126, 1185])
labels = ["label1", "label2", "label3", "label4", "label5", "label6"]
explode = ((fracs == max(fracs)).astype(int) / 20).tolist()
for val in range(2):
colors = sample(all_colors, len(fracs))
plt.figure(figsize=(8,8))
plt.pie(fracs, labels=labels, autopct='%1.1f%%',
shadow=True, explode=explode, colors=colors)
plt.legend(labels, loc=(1.05, 0.7), shadow=True)
plt.show()
Output
what is the difference between uint16_t and unsigned short int incase of 64 bit processor?
uint16_t
is unsigned 16-bit integer.
unsigned short int
is unsigned short integer, but the size is implementation dependent. The standard only says it's at least 16-bit (i.e, minimum value of UINT_MAX
is 65535
). In practice, it usually is 16-bit, but you can't take that as guaranteed.
Note:
- If you want a portable unsigned 16-bit integer, use
uint16_t
.
inttypes.h
and stdint.h
are both introduced in C99. If you are using C89, define your own type.
uint16_t
may not be provided in certain implementation(See reference below), but unsigned short int
is always available.
Reference: C11(ISO/IEC 9899:201x) §7.20 Integer types
For each type described herein that the implementation provides) shall declare that typedef name and define the associated macros. Conversely, for each type described herein that the implementation does not provide, shall not declare that typedef name nor shall it define the associated macros. An implementation shall provide those types described as ‘‘required’’, but need not provide any of the others (described as ‘optional’’).
Does adding a duplicate value to a HashSet/HashMap replace the previous value
Correct me if I'm wrong but what you're getting at is that with strings, "Hi" == "Hi" doesn't always come out true (because they're not necessarily the same object).
The reason you're getting an answer of 1 though is because the JVM will reuse strings objects where possible. In this case the JVM is reusing the string object, and thus overwriting the item in the Hashmap/Hashset.
But you aren't guaranteed this behavior (because it could be a different string object that has the same value "Hi"). The behavior you see is just because of the JVM's optimization.
what is .subscribe in angular?
A Subscription is an object that represents a disposable resource, usually the execution of an Observable. A Subscription has one important method, unsubscribe, that takes no argument and just disposes of the resource held by the subscription.
import { interval } from 'rxjs';
const observable = interval(1000);
const subscription = observable.subscribe(a=> console.log(a));
/** This cancels the ongoing Observable execution which
was started by calling subscribe with an Observer.*/
subscription.unsubscribe();
A Subscription essentially just has an unsubscribe() function to release resources or cancel Observable executions.
import { interval } from 'rxjs';
const observable1 = interval(400);
const observable2 = interval(300);
const subscription = observable1.subscribe(x => console.log('first: ' + x));
const childSubscription = observable2.subscribe(x => console.log('second: ' + x));
subscription.add(childSubscription);
setTimeout(() => {
// It unsubscribes BOTH subscription and childSubscription
subscription.unsubscribe();
}, 1000);
According to the official documentation, Angular should unsubscribe for you, but apparently, there is a bug.
Command not found after npm install in zsh
In my humble opinion, first, you have to make sure you have any kind of Node version installed. For that type:
nvm ls
And if you don't get any versions it means I was right :) Then you have to type:
nvm install <node_version**>
** the actual version you can find in Node website
Then you will have Node and you will be able to use npm commands
How to build query string with Javascript
I know this is very late answer but works very well...
var obj = {
a:"a",
b:"b"
}
Object.entries(obj).map(([key, val])=>`${key}=${val}`).join("&");
note: object.entries will return key,values pairs
output from above line will be a=a&b=b
Hope its helps someone.
Happy Coding...
High CPU Utilization in java application - why?
If a profiler is not applicable in your setup, you may try to identify the thread following steps in this post.
Basically, there are three steps:
- run
top -H
and get PID of the thread with highest CPU.
- convert the PID to hex.
- look for thread with the matching HEX PID in your thread dump.
Serialize form data to JSON
You can do this:
_x000D_
_x000D_
function onSubmit( form ){_x000D_
var data = JSON.stringify( $(form).serializeArray() ); // <-----------_x000D_
_x000D_
console.log( data );_x000D_
return false; //don't submit_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
_x000D_
<form onsubmit='return onSubmit(this)'>_x000D_
<input name='user' placeholder='user'><br>_x000D_
<input name='password' type='password' placeholder='password'><br>_x000D_
<button type='submit'>Try</button>_x000D_
</form>
_x000D_
_x000D_
_x000D_
see this: http://www.json.org/js.html
Can I add jars to maven 2 build classpath without installing them?
Using <scope>system</scope>
is a terrible idea for reasons explained by others, installing the file manually to your local repository makes the build unreproducible, and using <url>file://${project.basedir}/repo</url>
is not a good idea either because (1) that may not be a well-formed file
URL (e.g. if the project is checked out in a directory with unusual characters), (2) the result is unusable if this project’s POM is used as a dependency of someone else’s project.
Assuming you are unwilling to upload the artifact to a public repository, Simeon’s suggestion of a helper module does the job. But there is an easier way now…
The Recommendation
Use non-maven-jar-maven-plugin. Does exactly what you were asking for, with none of the drawbacks of the other approaches.
Substring in excel
What about using Replace all?
Just replace All on bracket to space.
And comma to space. And I think you can achieve it.
How to find the maximum value in an array?
If you can change the order of the elements:
int[] myArray = new int[]{1, 3, 8, 5, 7, };
Arrays.sort(myArray);
int max = myArray[myArray.length - 1];
If you can't change the order of the elements:
int[] myArray = new int[]{1, 3, 8, 5, 7, };
int max = Integer.MIN_VALUE;
for(int i = 0; i < myArray.length; i++) {
if(myArray[i] > max) {
max = myArray[i];
}
}
How to round up integer division and have int result in Java?
Use Math.ceil()
and cast the result to int:
- This is still faster than to avoid doubles by using abs().
- The result is correct when working with negatives, because -0.999 will be rounded UP to 0
Example:
(int) Math.ceil((double)divident / divisor);
No module named pkg_resources
sudo apt-get install --reinstall python-pkg-resources
fixed it for me in Debian. Seems like uninstalling some .deb packages (twisted set in my case) has broken the path python uses to find packages
Google Drive as FTP Server
I couldn't find a direct GDrive/DropBox solution. I'm also surprised there's no lazy solution for a free ftp host. Windows azure offers a ftp server "FTP connector" that's fairly easy to turn on at:
https://portal.azure.com
You can get a free 1 GB account by selecting "View All" machine types during your deployment.
Head and tail in one line
Under Python 3.x, you can do this nicely:
>>> head, *tail = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
>>> head
1
>>> tail
[1, 2, 3, 5, 8, 13, 21, 34, 55]
A new feature in 3.x is to use the *
operator in unpacking, to mean any extra values. It is described in PEP 3132 - Extended Iterable Unpacking. This also has the advantage of working on any iterable, not just sequences.
It's also really readable.
As described in the PEP, if you want to do the equivalent under 2.x (without potentially making a temporary list), you have to do this:
it = iter(iterable)
head, tail = next(it), list(it)
As noted in the comments, this also provides an opportunity to get a default value for head
rather than throwing an exception. If you want this behaviour, next()
takes an optional second argument with a default value, so next(it, None)
would give you None
if there was no head element.
Naturally, if you are working on a list, the easiest way without the 3.x syntax is:
head, tail = seq[0], seq[1:]
Defining private module functions in python
You can add an inner function:
def public(self, args):
def private(self.root, data):
if (self.root != None):
pass #do something with data
Something like that if you really need that level of privacy.
Trim a string in C
static inline void ut_trim(char * str) {
char * start = str;
char * end = start + strlen(str);
while (--end >= start) { /* trim right */
if (!isspace(*end))
break;
}
*(++end) = '\0';
while (isspace(*start)) /* trim left */
start++;
if (start != str) /* there is a string */
memmove(str, start, end - start + 1);
}
How to compare two NSDates: Which is more recent?
I have tried it hope it works for you
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
int unitFlags =NSDayCalendarUnit;
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
NSDate *myDate; //= [[NSDate alloc] init];
[dateFormatter setDateFormat:@"dd-MM-yyyy"];
myDate = [dateFormatter dateFromString:self.strPrevioisDate];
NSDateComponents *comps = [gregorian components:unitFlags fromDate:myDate toDate:[NSDate date] options:0];
NSInteger day=[comps day];
jQuery AJAX form data serialize using PHP
<form method="post" name="myForm" id="myForm">
replace with above form tag remove action from form tag. and set url : "check.php" in ajax
in your case first it goes to jQuery ajax then submit again the form. that's why it's creating issue.
i know i'm too late for this reply but i think it would help.
How to manage a redirect request after a jQuery Ajax call
in the servlet you should put
response.setStatus(response.SC_MOVED_PERMANENTLY);
to send the '301' xmlHttp status you need for a redirection...
and in the $.ajax function you should not use the .toString()
function..., just
if (xmlHttp.status == 301) {
top.location.href = 'xxxx.jsp';
}
the problem is it is not very flexible, you can't decide where you want to redirect..
redirecting through the servlets should be the best way. but i still can not find the right way to do it.
C# Convert string from UTF-8 to ISO-8859-1 (Latin1) H
Maybe it can help
Convert one codepage to another:
public static string fnStringConverterCodepage(string sText, string sCodepageIn = "ISO-8859-8", string sCodepageOut="ISO-8859-8")
{
string sResultado = string.Empty;
try
{
byte[] tempBytes;
tempBytes = System.Text.Encoding.GetEncoding(sCodepageIn).GetBytes(sText);
sResultado = System.Text.Encoding.GetEncoding(sCodepageOut).GetString(tempBytes);
}
catch (Exception)
{
sResultado = "";
}
return sResultado;
}
Usage:
string sMsg = "ERRO: Não foi possivel acessar o servico de Autenticação";
var sOut = fnStringConverterCodepage(sMsg ,"ISO-8859-1","UTF-8"));
Output:
"Não foi possivel acessar o servico de Autenticação"
How to get a DOM Element from a JQuery Selector
I needed to get the element as a string.
jQuery("#bob").get(0).outerHTML;
Which will give you something like:
<input type="text" id="bob" value="hello world" />
...as a string rather than a DOM element.
PHP multidimensional array search by value
No one else has used array_reduce yet, so thought I'd add this approach...
$find_by_uid = '100';
$is_in_array = array_reduce($userdb, function($carry, $user) use ($find_by_uid){
return $carry ? $carry : $user['uid'] === $find_by_uid;
});
// Returns true
Gives you more fine control over the 'search' logic than array_search().
Note that I have used strict equality here but you could opt for different comparison logic. The $carry means the comparison needs to be true once, and the final result will be TRUE.
How to get memory usage at runtime using C++?
Based on Don W's solution, with fewer variables.
void process_mem_usage(double& vm_usage, double& resident_set)
{
vm_usage = 0.0;
resident_set = 0.0;
// the two fields we want
unsigned long vsize;
long rss;
{
std::string ignore;
std::ifstream ifs("/proc/self/stat", std::ios_base::in);
ifs >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore
>> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore >> ignore
>> ignore >> ignore >> vsize >> rss;
}
long page_size_kb = sysconf(_SC_PAGE_SIZE) / 1024; // in case x86-64 is configured to use 2MB pages
vm_usage = vsize / 1024.0;
resident_set = rss * page_size_kb;
}
How to check if a variable is not null?
They are not equivalent. The first will execute the block following the if
statement if myVar
is truthy (i.e. evaluates to true
in a conditional), while the second will execute the block if myVar
is any value other than null
.
The only values that are not truthy in JavaScript are the following (a.k.a. falsy values):
null
undefined
0
""
(the empty string)
false
NaN
Must issue a STARTTLS command first
Try this code :
Properties props = new Properties();
props.put("mail.smtp.host", "smtp.gmail.com");
props.put("mail.smtp.socketFactory.port", "465");
props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
props.put("mail.smtp.auth", "true");
props.put("mail.smtp.prot", "465");
Session session = Session.getDefaultInstance(props,
new javax.mail.Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication("PUT THE MAIL SENDER HERE !", "PUT THE PASSWORD OF THE MAIL SENDER HERE !");
}
}
);
try {
Message message = new MimeMessage(session);
message.setFrom(new InternetAddress("PUT THE MAIL SENDER HERE !"));
message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("PUT THE MAIL RECEIVER HERE !"));
message.setSubject("MAIL SUBJECT !");
message.setText("MAIL BODY !");
Transport.send(message);
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e);
}
You have to less secure the security of the mail sender. if the problem persist I think It can be caused by the antivirus, try to disable it ..
Android - How to regenerate R class?
In order to regenerate the R.class, you will have to try multiple techniques.
- Remove any R imports from your java source files:
import R.android
- Make sure to open the "Problems" panel by going to Window->Show view->Problems
- If you do have some errors in your xml resources, you will need to correct those errors. In my case I had to change my id attributes to include the "+" sign as follows:
android:id="@+id/grp_txt"
- Now proceed to do Project->Clean
- Finally do Project->Close, Project->Open
The "+" sign indicates a new resource id and the forces the aapt tool to create a new resource integer in the R.java class.
How to run a javascript function during a mouseover on a div
Here is how I show hover text using JavaScript tooltip:
<script language="JavaScript" type="text/javascript" src="javascript/wz_tooltip.js"></script>
<div class="curhand" onmouseover="this.T_WIDTH=125; return escape('Welcome')">Are you New Here?</div>
SQL to LINQ Tool
Bill Horst's - Converting SQL to LINQ is a very good resource for this task (as well as LINQPad).
LINQ Tools has a decent list of tools as well but I do not believe there is anything else out there that can do what Linqer did.
Generally speaking, LINQ is a higher-level querying language than SQL which can cause translation loss when trying to convert SQL to LINQ. For one, LINQ emits shaped results and SQL flat result sets. The issue here is that an automatic translation from SQL to LINQ will often have to perform more transliteration than translation - generating examples of how NOT to write LINQ queries. For this reason, there are few (if any) tools that will be able to reliably convert SQL to LINQ. Analogous to learning C# 4 by first converting VB6 to C# 4 and then studying the resulting conversion.
How to draw a path on a map using kml file?
Mathias Lin code working beautifully. However, you might want to consider changing this part inside drawPath method:
if (lngLat.length >= 2 && gp1.getLatitudeE6() > 0 && gp1.getLongitudeE6() > 0
&& gp2.getLatitudeE6() > 0 && gp2.getLongitudeE6() > 0) {
GeoPoint can be less than zero as well, I switch mine to:
if (lngLat.length >= 2 && gp1.getLatitudeE6() != 0 && gp1.getLongitudeE6() != 0
&& gp2.getLatitudeE6() != 0 && gp2.getLongitudeE6() != 0) {
Thank you :D
Convert string to Date in java
it went OK when i used Locale.US
parametre in SimpleDateFormat
String dateString = "15 May 2013 17:38:34 +0300";
System.out.println(dateString);
SimpleDateFormat dateFormat = new SimpleDateFormat("dd MMM yyyy HH:mm:ss Z", Locale.US);
DateFormat targetFormat = new SimpleDateFormat("dd MMM yyyy HH:mm", Locale.getDefault());
String formattedDate = null;
Date convertedDate = new Date();
try {
convertedDate = dateFormat.parse(dateString);
System.out.println(dateString);
formattedDate = targetFormat.format(convertedDate);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(convertedDate);
Bootstrap NavBar with left, center or right aligned items
You can use this format
<!-- NAVBAR START -->
<nav class="navbar py-3 py-4 text-uppercase nav-over-video navbar-expand-lg navbar-white bg-white">
<div class="container-fluid d-flex">
<div class="justify-content-start">
<a class="navbar-brand" href="#">
<img src="img/logo.png" height="50px" alt="" class="img">
</a>
</div>
<div class="justify-content-end">
<button class="navbar-toggler" type="button" data-bs-toggle="collapse"
data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent"
aria-expanded="false" aria-label="Toggle navigation">
<span>
<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor"
class="bi bi-menu-button-wide" viewBox="0 0 16 16">
<path
d="M0 1.5A1.5 1.5 0 0 1 1.5 0h13A1.5 1.5 0 0 1 16 1.5v2A1.5 1.5 0 0 1 14.5 5h-13A1.5 1.5 0 0 1 0 3.5v-2zM1.5 1a.5.5 0 0 0-.5.5v2a.5.5 0 0 0 .5.5h13a.5.5 0 0 0 .5-.5v-2a.5.5 0 0 0-.5-.5h-13z" />
<path
d="M2 2.5a.5.5 0 0 1 .5-.5h3a.5.5 0 0 1 0 1h-3a.5.5 0 0 1-.5-.5zm10.823.323l-.396-.396A.25.25 0 0 1 12.604 2h.792a.25.25 0 0 1 .177.427l-.396.396a.25.25 0 0 1-.354 0zM0 8a2 2 0 0 1 2-2h12a2 2 0 0 1 2 2v5a2 2 0 0 1-2 2H2a2 2 0 0 1-2-2V8zm1 3v2a1 1 0 0 0 1 1h12a1 1 0 0 0 1-1v-2H1zm14-1V8a1 1 0 0 0-1-1H2a1 1 0 0 0-1 1v2h14zM2 8.5a.5.5 0 0 1 .5-.5h9a.5.5 0 0 1 0 1h-9a.5.5 0 0 1-.5-.5zm0 4a.5.5 0 0 1 .5-.5h6a.5.5 0 0 1 0 1h-6a.5.5 0 0 1-.5-.5z" />
</svg>
</span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button"
data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdown">
<li><a class="dropdown-item" href="#">Action</a></li>
<li><a class="dropdown-item" href="#">Another action</a></li>
<li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>
</li>
</ul>
</div>
</div>
</div>
</nav>
<!-- As a link -->
<!-- NAVBAR ENDS -->
MySQL Error 1093 - Can't specify target table for update in FROM clause
NexusRex provided a very good solution for deleting with join from the same table.
If you do this:
DELETE FROM story_category
WHERE category_id NOT IN (
SELECT DISTINCT category.id AS cid FROM category
INNER JOIN story_category ON category_id=category.id
)
you are going to get an error.
But if you wrap the condition in one more select:
DELETE FROM story_category
WHERE category_id NOT IN (
SELECT cid FROM (
SELECT DISTINCT category.id AS cid FROM category
INNER JOIN story_category ON category_id=category.id
) AS c
)
it would do the right thing!!
Explanation: The query optimizer does a derived merge optimization for the first query (which causes it to fail with the error), but the second query doesn't qualify for the derived merge optimization. Hence the optimizer is forced to execute the subquery first.
Good MapReduce examples
From time to time I present MR concepts to people. I find processing tasks familiar to people and then map them to the MR paradigm.
Usually I take two things:
Group By / Aggregations. Here the advantage of the shuffling stage is clear. An explanation that shuffling is also distributed sort + an explanation of distributed sort algorithm also helps.
Join of two tables. People working with DB are familiar with the concept and its scalability problem. Show how it can be done in MR.
SCCM 2012 application install "Failed" in client Software Center
The execmgr.log
will show the commandline and ccmcache folder used for installation. Typically, required apps don't show on appenforce.log
and some clients will have outdated appenforce
or no ppenforce.log
files.
execmgr.log
also shows required hidden uninstall actions as well.
You may want to save the blog link. I still reference it from time to time.
open the file upload dialogue box onclick the image
<input type="file" id="imgupload" style="display:none"/>
<label for='imgupload'> <button id="OpenImgUpload">Image Upload</button></label>
On click of for= attribute will automatically focus on "file input" and upload dialog box will open
Get hours difference between two dates in Moment Js
var timecompare = {
tstr: "",
get: function (current_time, startTime, endTime) {
this.tstr = "";
var s = current_time.split(":"), t1 = tm1.split(":"), t2 = tm2.split(":"), t1s = Number(t1[0]), t1d = Number(t1[1]), t2s = Number(t2[0]), t2d = Number(t2[1]);
if (t1s < t2s) {
this.t(t1s, t2s);
}
if (t1s > t2s) {
this.t(t1s, 23);
this.t(0, t2s);
}
var saat_dk = Number(s[1]);
if (s[0] == tm1.substring(0, 2) && saat_dk >= t1d)
return true;
if (s[0] == tm2.substring(0, 2) && saat_dk <= t2d)
return true;
if (this.tstr.indexOf(s[0]) != 1 && this.tstr.indexOf(s[0]) != -1 && !(this.tstr.indexOf(s[0]) == this.tstr.length - 2))
return true;
return false;
},
t: function (ii, brk) {
for (var i = 0; i <= 23; i++) {
if (i < ii)
continue;
var s = (i < 10) ? "0" + i : i + "";
this.tstr += "," + s;
if (brk == i)
break;
}
}};
What is "overhead"?
The meaning of the word can differ a lot with context. In general, it's resources (most often memory and CPU time) that are used, which do not contribute directly to the intended result, but are required by the technology or method that is being used. Examples:
- Protocol overhead: Ethernet frames, IP packets and TCP segments all have headers, TCP connections require handshake packets. Thus, you cannot use the entire bandwidth the hardware is capable of for your actual data. You can reduce the overhead by using larger packet sizes and UDP has a smaller header and no handshake.
- Data structure memory overhead: A linked list requires at least one pointer for each element it contains. If the elements are the same size as a pointer, this means a 50% memory overhead, whereas an array can potentially have 0% overhead.
- Method call overhead: A well-designed program is broken down into lots of short methods. But each method call requires setting up a stack frame, copying parameters and a return address. This represents CPU overhead compared to a program that does everything in a single monolithic function. Of course, the added maintainability makes it very much worth it, but in some cases, excessive method calls can have a significant performance impact.
How do I discover memory usage of my application in Android?
1) I guess not, at least not from Java.
2)
ActivityManager activityManager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
MemoryInfo mi = new MemoryInfo();
activityManager.getMemoryInfo(mi);
Log.i("memory free", "" + mi.availMem);
Posting raw image data as multipart/form-data in curl
In case anyone had the same problem: check this as @PravinS suggested. I used the exact same code as shown there and it worked for me perfectly.
This is the relevant part of the server code that helped:
if (isset($_POST['btnUpload']))
{
$url = "URL_PATH of upload.php"; // e.g. http://localhost/myuploader/upload.php // request URL
$filename = $_FILES['file']['name'];
$filedata = $_FILES['file']['tmp_name'];
$filesize = $_FILES['file']['size'];
if ($filedata != '')
{
$headers = array("Content-Type:multipart/form-data"); // cURL headers for file uploading
$postfields = array("filedata" => "@$filedata", "filename" => $filename);
$ch = curl_init();
$options = array(
CURLOPT_URL => $url,
CURLOPT_HEADER => true,
CURLOPT_POST => 1,
CURLOPT_HTTPHEADER => $headers,
CURLOPT_POSTFIELDS => $postfields,
CURLOPT_INFILESIZE => $filesize,
CURLOPT_RETURNTRANSFER => true
); // cURL options
curl_setopt_array($ch, $options);
curl_exec($ch);
if(!curl_errno($ch))
{
$info = curl_getinfo($ch);
if ($info['http_code'] == 200)
$errmsg = "File uploaded successfully";
}
else
{
$errmsg = curl_error($ch);
}
curl_close($ch);
}
else
{
$errmsg = "Please select the file";
}
}
html form should look something like:
<form action="uploadpost.php" method="post" name="frmUpload" enctype="multipart/form-data">
<tr>
<td>Upload</td>
<td align="center">:</td>
<td><input name="file" type="file" id="file"/></td>
</tr>
<tr>
<td> </td>
<td align="center"> </td>
<td><input name="btnUpload" type="submit" value="Upload" /></td>
</tr>
An explicit value for the identity column in table can only be specified when a column list is used and IDENTITY_INSERT is ON SQL Server
For if you want to insert your values from one table to another through a stored procedure. I used this and this, the latter which is almost like Andomar's answer.
CREATE procedure [dbo].[RealTableMergeFromTemp]
with execute as owner
AS
BEGIN
BEGIN TRANSACTION RealTableDataMerge
SET XACT_ABORT ON
DECLARE @columnNameList nvarchar(MAX) =
STUFF((select ',' + a.name
from sys.all_columns a
join sys.tables t on a.object_id = t.object_id
where t.object_id = object_id('[dbo].[RealTable]')
order by a.column_id
for xml path ('')
),1,1,'')
DECLARE @SQLCMD nvarchar(MAX) =N'INSERT INTO [dbo].[RealTable] (' + @columnNameList + N') SELECT * FROM [#Temp]'
SET IDENTITY_INSERT [dbo].[RealTable] ON;
exec(@sqlcmd)
SET IDENTITY_INSERT [dbo].[RealTable] OFF
COMMIT TRANSACTION RealTableDataMerge
END
GO
Read values into a shell variable from a pipe
Because I fall for it, I would like to drop a note.
I found this thread, because I have to rewrite an old sh script
to be POSIX compatible.
This basically means to circumvent the pipe/subshell problem introduced by POSIX by rewriting code like this:
some_command | read a b c
into:
read a b c << EOF
$(some_command)
EOF
And code like this:
some_command |
while read a b c; do
# something
done
into:
while read a b c; do
# something
done << EOF
$(some_command)
EOF
But the latter does not behave the same on empty input.
With the old notation the while loop is not entered on empty input,
but in POSIX notation it is!
I think it's due to the newline before EOF,
which cannot be ommitted.
The POSIX code which behaves more like the old notation
looks like this:
while read a b c; do
case $a in ("") break; esac
# something
done << EOF
$(some_command)
EOF
In most cases this should be good enough.
But unfortunately this still behaves not exactly like the old notation
if some_command prints an empty line.
In the old notation the while body is executed
and in POSIX notation we break in front of the body.
An approach to fix this might look like this:
while read a b c; do
case $a in ("something_guaranteed_not_to_be_printed_by_some_command") break; esac
# something
done << EOF
$(some_command)
echo "something_guaranteed_not_to_be_printed_by_some_command"
EOF
How to change color and font on ListView
use them in Java code like this:
color = getResources().getColor(R.color.mycolor);
The getResources()
method returns the ResourceManager class for the current activity, and getColor()
asks the manager to look up a color given a resource ID
Return an empty Observable
RxJS 6
you can use also from function like below:
return from<string>([""]);
after import:
import {from} from 'rxjs';
In java how to get substring from a string till a character c?
In java.lang.String you get some methods like indexOf(): which returns you first index of a char/string.
and lstIndexOf: which returns you the last index of String/char
From Java Doc:
public int indexOf(int ch)
public int indexOf(String str)
Returns the index within this string of the first occurrence of the specified character.
How to thoroughly purge and reinstall postgresql on ubuntu?
I was following the replies,
When editing /etc/group I also deleted this line:
ssl-cert:x:112:postgres
then, when trying to install postgresql, I got this error
Preconfiguring packages ...
dpkg: unrecoverable fatal error, aborting:
syntax error: unknown group 'ssl-cert' in statoverride file
E: Sub-process /usr/bin/dpkg returned an error code (2)
Putting the "ssl-cert:x:112:postgres" line back in /etc/group seems to fix it (so I was able to install postgresql)
Polling the keyboard (detect a keypress) in python
If you combine time.sleep, threading.Thread, and sys.stdin.read you can easily wait for a specified amount of time for input and then continue,
also this should be cross-platform compatible.
t = threading.Thread(target=sys.stdin.read(1) args=(1,))
t.start()
time.sleep(5)
t.join()
You could also place this into a function like so
def timed_getch(self, bytes=1, timeout=1):
t = threading.Thread(target=sys.stdin.read, args=(bytes,))
t.start()
time.sleep(timeout)
t.join()
del t
Although this will not return anything so instead you should use the multiprocessing pool module you can find that here: how to get the return value from a thread in python?
How can I create and style a div using JavaScript?
You can just use the method below:
document.write()
It is very simple, in the doc below I explain
_x000D_
_x000D_
document.write("<div class='div'>Some content inside the div (It is styled!)</div>")
_x000D_
.div {
background-color: red;
padding: 5px;
color: #fff;
font-family: Arial;
cursor: pointer;
}
.div:hover {
background-color: blue;
padding: 10px;
}
.div:hover:before {
content: 'Hover! ';
}
.div:active {
background-color: green;
padding: 15px;
}
.div:active:after {
content: ' Active! or clicked...';
}
_x000D_
<p>Below or above well show the div</p>
<p>Try pointing hover it and clicking on it. Those are tha styles aplayed. The text and background color changes.</p>
_x000D_
_x000D_
_x000D_
How to generate XML file dynamically using PHP?
$query=mysql_query("select * from tablename")or die(mysql_error());
$xml="<libraray>\n\t\t";
while($data=mysql_fetch_array($query))
{
$xml .="<mail_address>\n\t\t";
$xml .= "<id>".$data['id']."</id>\n\t\t";
$xml .= "<email>".$data['email_address']."</email>\n\t\t";
$xml .= "<verify_code>".$data['verify']."</verify_code>\n\t\t";
$xml .= "<status>".$data['status']."</status>\n\t\t";
$xml.="</mail_address>\n\t";
}
$xml.="</libraray>\n\r";
$xmlobj=new SimpleXMLElement($xml);
$xmlobj->asXML("text.xml");
Its simple just connect with your database it will create test.xml file in your project folder
How to get ID of clicked element with jQuery
Your IDs are #1
, and cycle
just wants a number passed to it. You need to remove the #
before calling cycle
.
$('a.pagerlink').click(function() {
var id = $(this).attr('id');
$container.cycle(id.replace('#', ''));
return false;
});
Also, IDs shouldn't contain the #
character, it's invalid (numeric IDs are also invalid). I suggest changing the ID to something like pager_1
.
<a href="#" id="pager_1" class="pagerlink" >link</a>
$('a.pagerlink').click(function() {
var id = $(this).attr('id');
$container.cycle(id.replace('pager_', ''));
return false;
});
What is a PDB file?
I had originally asked myself the question "Do I need a PDB file deployed to my customer's machine?", and after reading this post, decided to exclude the file.
Everything worked fine, until today, when I was trying to figure out why a message box containing an Exception.StackTrace
was missing the file and line number information - necessary for troubleshooting the exception. I re-read this post and found the key nugget of information: that although the PDB is not necessary for the app to run, it is necessary for the file and line numbers to be present in the StackTrace
string. I included the PDB file in the executable folder and now all is fine.
Linq to SQL .Sum() without group ... into
you can:
itemsCart.Select(c=>c.Price).Sum();
To hit the db only once do:
var itemsInCart = (from o in db.OrderLineItems
where o.OrderId == currentOrder.OrderId
select new { o.OrderLineItemId, ..., ..., o.WishListItem.Price}
).ToList();
var sum = itemsCart.Select(c=>c.Price).Sum();
The extra round-trip saved is worth it :)
react-router scroll to top on every transition
In your router.js
, just add this function in the router
object. This will do the job.
scrollBehavior() {
document.getElementById('app').scrollIntoView();
},
Like this,
**Routes.js**
import vue from 'blah!'
import Router from 'blah!'
let router = new Router({
mode: 'history',
base: process.env.BASE_URL,
scrollBehavior() {
document.getElementById('app').scrollIntoView();
},
routes: [
{ url: "Solar System" },
{ url: "Milky Way" },
{ url: "Galaxy" },
]
});
sql server #region
Not really, Sorry! But...
Adding begin
and end
.. with a comment on the begin
creates regions which would look like this...bit of hack though!
Otherwise you can only expand and collapse you just can't dictate what should be expanded and collapsed. Not without a third-party tool such as SSMS Tools Pack.
.ps1 cannot be loaded because the execution of scripts is disabled on this system
There are certain scenarios in which you can follow the steps suggested in the other answers, verify that Execution Policy is set correctly, and still have your scripts fail. If this happens to you, you are probably on a 64-bit machine with both 32-bit and 64-bit versions of PowerShell, and the failure is happening on the version that doesn't have Execution Policy set. The setting does not apply to both versions, so you have to explicitly set it twice.
Look in your Windows directory for System32 and SysWOW64.
Repeat these steps for each directory:
- Navigate to WindowsPowerShell\v1.0 and launch powershell.exe
Check the current setting for ExecutionPolicy:
Get-ExecutionPolicy -List
Set the ExecutionPolicy for the level and scope you want, for example:
Set-ExecutionPolicy -Scope LocalMachine Unrestricted
Note that you may need to run PowerShell as administrator depending on the scope you are trying to set the policy for.
You can read a lot more here: Running Windows PowerShell Scripts
Sass Variable in CSS calc() function
I have tried this then i fixed my issue. It will calculate all media-breakpoint automatically by given rate (base-size/rate-size)
$base-size: 16;
$rate-size-xl: 24;
// set default size for all cases;
:root {
--size: #{$base-size};
}
// if it's smaller then LG it will set size rate to 16/16;
// example: if size set to 14px, it will be 14px * 16 / 16 = 14px
@include media-breakpoint-down(lg) {
:root {
--size: #{$base-size};
}
}
// if it is bigger then XL it will set size rate to 24/16;
// example: if size set to 14px, it will be 14px * 24 / 16 = 21px
@include media-breakpoint-up(xl) {
:root {
--size: #{$rate-size-xl};
}
}
@function size($px) {
@return calc(#{$px} / $base-size * var(--size));
}
div {
font-size: size(14px);
width: size(150px);
}
Change a branch name in a Git repo
Assuming you're currently on the branch you want to rename:
git branch -m newname
This is documented in the manual for git-branch
, which you can view using
man git-branch
or
git help branch
Specifically, the command is
git branch (-m | -M) [<oldbranch>] <newbranch>
where the parameters are:
<oldbranch>
The name of an existing branch to rename.
<newbranch>
The new name for an existing branch. The same restrictions as for <branchname> apply.
<oldbranch>
is optional, if you want to rename the current branch.
Align an element to bottom with flexbox
1. Style parent element: style="display:flex; flex-direction:column; flex:1;"
2. Style the element you want to stay at bottom: style="margin-top: auto;"
3. Done! Wow. That was easy.
Example:
<section style="display:flex; flex-wrap:wrap;"> // For demo, not necessary
<div style="display:flex; flex-direction:column; flex:1;"> // Parent element
<button style="margin-top: auto;"> I </button> // Target element
</div>
... 5 more identical divs, for demo ...
</section>
Demo: https://codepen.io/ferittuncer/pen/YzygpWX
Append an empty row in dataframe using pandas
Append "empty" row to data frame and fill selected cells:
Generate empty data frame (no rows just columns a
and b
):
import pandas as pd
col_names = ["a","b"]
df = pd.DataFrame(columns = col_names)
Append empty row at the end of the data frame:
df = df.append(pd.Series(), ignore_index = True)
Now fill the empty cell at the end (len(df)-1
) of the data frame in column a
:
df.loc[[len(df)-1],'a'] = 123
Result:
a b
0 123 NaN
And of course one can iterate over the rows and fill cells:
col_names = ["a","b"]
df = pd.DataFrame(columns = col_names)
for x in range(0,5):
df = df.append(pd.Series(), ignore_index = True)
df.loc[[len(df)-1],'a'] = 123
Result:
a b
0 123 NaN
1 123 NaN
2 123 NaN
3 123 NaN
4 123 NaN
Python List & for-each access (Find/Replace in built-in list)
Answering this has been good, as the comments have led to an improvement in my own understanding of Python variables.
As noted in the comments, when you loop over a list with something like for member in my_list
the member
variable is bound to each successive list element. However, re-assigning that variable within the loop doesn't directly affect the list itself. For example, this code won't change the list:
my_list = [1,2,3]
for member in my_list:
member = 42
print my_list
Output:
[1, 2, 3]
If you want to change a list containing immutable types, you need to do something like:
my_list = [1,2,3]
for ndx, member in enumerate(my_list):
my_list[ndx] += 42
print my_list
Output:
[43, 44, 45]
If your list contains mutable objects, you can modify the current member
object directly:
class C:
def __init__(self, n):
self.num = n
def __repr__(self):
return str(self.num)
my_list = [C(i) for i in xrange(3)]
for member in my_list:
member.num += 42
print my_list
[42, 43, 44]
Note that you are still not changing the list, simply modifying the objects in the list.
You might benefit from reading Naming and Binding.
Webpack how to build production code and how to use it
You can use argv npm module (install it by running npm install argv --save) for getting params in your webpack.config.js file and as for production you use -p flag "build": "webpack -p", you can add condition in webpack.config.js file like below
plugins: [
new webpack.DefinePlugin({
'process.env':{
'NODE_ENV': argv.p ? JSON.stringify('production') : JSON.stringify('development')
}
})
]
And thats it.
Can you do a For Each Row loop using MySQL?
In the link you provided, thats not a loop in sql...
thats a loop in programming language
they are first getting list of all distinct districts, and then for each district executing query again.
Styling JQuery UI Autocomplete
You can overwrite the classes in your own css using !important, e.g. if you want to get rid of the rounded corners.
.ui-corner-all
{
border-radius: 0px !important;
}
How can I strip HTML tags from a string in ASP.NET?
For the second parameter,i.e. keep some tags, you may need some code like this by using HTMLagilityPack:
public string StripTags(HtmlNode documentNode, IList keepTags)
{
var result = new StringBuilder();
foreach (var childNode in documentNode.ChildNodes)
{
if (childNode.Name.ToLower() == "#text")
{
result.Append(childNode.InnerText);
}
else
{
if (!keepTags.Contains(childNode.Name.ToLower()))
{
result.Append(StripTags(childNode, keepTags));
}
else
{
result.Append(childNode.OuterHtml.Replace(childNode.InnerHtml, StripTags(childNode, keepTags)));
}
}
}
return result.ToString();
}
More explanation on this page: http://nalgorithm.com/2015/11/20/strip-html-tags-of-an-html-in-c-strip_html-php-equivalent/
How to find the files that are created in the last hour in unix
If the dir to search is srch_dir
then either
$ find srch_dir -cmin -60 # change time
or
$ find srch_dir -mmin -60 # modification time
or
$ find srch_dir -amin -60 # access time
shows files created, modified or accessed in the last hour.
correction :ctime is for change node time (unsure though, please correct me )
How to escape strings in SQL Server using PHP?
For the conversion to get the hexadecimal values in SQL back into ASCII, here is the solution I got on this (using the function from user chaos to encode into hexadecimal)
function hexEncode($data) {
if(is_numeric($data))
return $data;
$unpacked = unpack('H*hex', $data);
return '0x' . $unpacked['hex'];
}
function hexDecode($hex) {
$str = '';
for ($i=0; $i<strlen($hex); $i += 2)
$str .= chr(hexdec(substr($hex, $i, 2)));
return $str;
}
$stringHex = hexEncode('Test String');
var_dump($stringHex);
$stringAscii = hexDecode($stringHex);
var_dump($stringAscii);
javascript getting my textbox to display a variable
You're on the right track with using document.getElementById()
as you have done for your first two text boxes. Use something like document.getElementById("textbox3")
to retrieve the element. Then you can just set its value property: document.getElementById("textbox3").value = answer;
For the "Your answer is: --", I'd recommend wrapping the "--" in a <span/>
(e.g. <span id="answerDisplay">--</span>
). Then use document.getElementById("answerDisplay").textContent = answer;
to display it.
Linux Command History with date and time
It depends on the shell (and its configuration) in standard bash only the command is stored without the date and time (check .bash_history
if there is any timestamp there).
To have bash store the timestamp you need to set HISTTIMEFORMAT
before executing the commands, e.g. in .bashrc
or .bash_profile
. This will cause bash to store the timestamps in .bash_history
(see the entries starting with #
).
Split Java String by New Line
If, for some reason, you don't want to use String.split
(for example, because of regular expressions) and you want to use functional programming on Java 8 or newer:
List<String> lines = new BufferedReader(new StringReader(string))
.lines()
.collect(Collectors.toList());
Contain an image within a div?
object-fit
, behaves like background-size
, solving the issue of scaling images up and down to fit.
The object-fit CSS property specifies how the contents of a replaced element should be fitted to the box established by its used height and width.
https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit
.cover img {
width: 100%;
height: 100%;
object-fit: cover;
overflow: hidden;
}
Browser Support
There's no IE support, and support in Edge begins at v16, only for img
element: https://caniuse.com/#search=object-fit
The bfred-it/object-fit-images polyfill works very well for me in IE11, tested on Browserstack: demo.
Alternative without polyfill using an image in SVG
For Edge pre v16, and ie9, ie10, ie11:
You can crop and scale any image using CSS object-fit
and object-position
. However, these properties are only supported in the latest version of MS Edge as well as all other modern browsers.
If you need to crop and scale an image in Internet Explorer and provide support back to IE9, you can do that by wrapping the image in an <svg>
, and using the viewBox
and preserveAspectRatio
attributes to do what object-fit
and object-position
do.
http://www.sarasoueidan.com/blog/svg-object-fit/#summary-recap
(The author explains the technique thoroughly, and duplicating the detail here would be impractical.)
size of NumPy array
Yes numpy has a size function, and shape and size are not quite the same.
Input
import numpy as np
data = [[1, 2, 3, 4], [5, 6, 7, 8]]
arrData = np.array(data)
print(data)
print(arrData.size)
print(arrData.shape)
Output
[[1, 2, 3, 4], [5, 6, 7, 8]]
8 # size
(2, 4) # shape
How to print full stack trace in exception?
I usually use the .ToString() method on exceptions to present the full exception information (including the inner stack trace) in text:
catch (MyCustomException ex)
{
Debug.WriteLine(ex.ToString());
}
Sample output:
ConsoleApplication1.MyCustomException: some message .... ---> System.Exception: Oh noes!
at ConsoleApplication1.SomeObject.OtherMethod() in C:\ConsoleApplication1\SomeObject.cs:line 24
at ConsoleApplication1.SomeObject..ctor() in C:\ConsoleApplication1\SomeObject.cs:line 14
--- End of inner exception stack trace ---
at ConsoleApplication1.SomeObject..ctor() in C:\ConsoleApplication1\SomeObject.cs:line 18
at ConsoleApplication1.Program.DoSomething() in C:\ConsoleApplication1\Program.cs:line 23
at ConsoleApplication1.Program.Main(String[] args) in C:\ConsoleApplication1\Program.cs:line 13
How to get CRON to call in the correct PATHs
On my AIX cron picks up it's environmental variables from /etc/environment ignoring what is set in the .profile.
Edit: I also checked out a couple of Linux boxes of various ages and these appear to have this file as well, so this is likely not AIX specific.
I checked this using joemaller's cron suggestion and checking the output before and after editing the PATH variable in /etc/environment.
How to put wildcard entry into /etc/hosts?
use dnsmasq
pretending you're using a debian-based dist(ubuntu,mint..), check if it's installed with
(sudo) systemctl status dnsmasq
If it is just disabled start it with
(sudo) systemctl start dnsmasq
If you have to install it, write
(sudo) apt-get install dnsmasq
To define domains to resolve edit /etc/dnsmasq.conf
like this
address=/example.com/127.0.0.1
to resolve *.example.com
! You need to reload dnsmasq to take effect for the changes !
systemctl reload dnsmasq
How to use pull to refresh in Swift?
You can achieve this by using few lines of code. So why you are going to stuck in third party library or UI.
Pull to refresh is built in iOS. You could do this in swift like
var pullControl = UIRefreshControl()
override func viewDidLoad() {
super.viewDidLoad()
pullControl.attributedTitle = NSAttributedString(string: "Pull to refresh")
pullControl.addTarget(self, action: #selector(pulledRefreshControl(_:)), for: UIControl.Event.valueChanged)
tableView.addSubview(pullControl) // not required when using UITableViewController
}
@objc func pulledRefreshControl(sender:AnyObject) {
// Code to refresh table view
}
ERROR 1115 (42000): Unknown character set: 'utf8mb4'
I am answering the question - as I didn't find any of them complete. As nowadays Unknown character set: 'utf8mb4' is quite prevalent as lot of deployments have MySQL less then 5.5.3 (version in which utf8mb4 was added).
The error clearly states that you don't have utf8mb4
supported on your stage db server.
Cause: probably locally you have MySQL
version 5.5.3 or greater, and on stage/hosted VPS you have MySQL server version less then 5.5.3
The utf8mb4
character sets was added in MySQL 5.5.3.
utf8mb4
was added because of a bug in MySQL's utf8
character set.
MySQL's handling of the utf8 character set only allows a maximum of 3
bytes for a single codepoint, which isn't enough to represent the
entirety of Unicode (Maximum codepoint = 0x10FFFF
). Because they
didn't want to potentially break any stuff that relied on this buggy
behaviour, utf8mb4
was added. Documentation here.
From SO answer:
Verification:
To verify you can check the current character set and collation for the DB you're importing the dump from - How do I see what character set a MySQL database / table / column is?
Solution 1: Simply upgrade your MySQL server to 5.5.3 (at-least) - for next time be conscious about the version you use locally, for stage, and for prod, all must have to be same. A suggestion - in present the default character set should be utf8mb4.
Solution 2 (not recommended): Convert the current character set to utf8, and then export the data - it'll load ok.
Android Use Done button on Keyboard to click button
You can use this one also (sets a special listener to be called when an action is performed on the EditText), it works both for DONE and RETURN:
max.setOnEditorActionListener(new OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
if ((event != null && (event.getKeyCode() == KeyEvent.KEYCODE_ENTER)) || (actionId == EditorInfo.IME_ACTION_DONE)) {
Log.i(TAG,"Enter pressed");
}
return false;
}
});
Passing variable from Form to Module in VBA
Siddharth's answer is nice, but relies on globally-scoped variables. There's a better, more OOP-friendly way.
A UserForm is a class module like any other - the only difference is that it has a hidden VB_PredeclaredId
attribute set to True
, which makes VB create a global-scope object variable named after the class - that's how you can write UserForm1.Show
without creating a new instance of the class.
Step away from this, and treat your form as an object instead - expose Property Get
members and abstract away the form's controls - the calling code doesn't care about controls anyway:
Option Explicit
Private cancelling As Boolean
Public Property Get UserId() As String
UserId = txtUserId.Text
End Property
Public Property Get Password() As String
Password = txtPassword.Text
End Property
Public Property Get IsCancelled() As Boolean
IsCancelled = cancelling
End Property
Private Sub OkButton_Click()
Me.Hide
End Sub
Private Sub CancelButton_Click()
cancelling = True
Me.Hide
End Sub
Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
If CloseMode = VbQueryClose.vbFormControlMenu Then
cancelling = True
Cancel = True
Me.Hide
End If
End Sub
Now the calling code can do this (assuming the UserForm was named LoginPrompt
):
With New LoginPrompt
.Show vbModal
If .IsCancelled Then Exit Sub
DoSomething .UserId, .Password
End With
Where DoSomething
would be some procedure that requires the two string parameters:
Private Sub DoSomething(ByVal uid As String, ByVal pwd As String)
'work with the parameter values, regardless of where they came from
End Sub
Function to convert column number to letter?
If you'd rather not use a range object:
Function ColumnLetter(ColumnNumber As Long) As String
Dim n As Long
Dim c As Byte
Dim s As String
n = ColumnNumber
Do
c = ((n - 1) Mod 26)
s = Chr(c + 65) & s
n = (n - c) \ 26
Loop While n > 0
ColumnLetter = s
End Function
Arithmetic overflow error converting numeric to data type numeric
If you want to reduce the size to decimal(7,2) from decimal(9,2) you will have to account for the existing data with values greater to fit into decimal(7,2). Either you will have to delete those numbers are truncate it down to fit into your new size. If there was no data for the field you are trying to update it will do it automatically without issues
How to set app icon for Electron / Atom Shell App
If you want to update the app icon in the taskbar, then Update following in main.js (if using typescript then main.ts)
win.setIcon(path.join(__dirname, '/src/assets/logo-small.png'));
__dirname
points to the root directory (same directory as package.json
) of your application.
Most efficient conversion of ResultSet to JSON?
the other way , here I have used ArrayList and Map, so its not call json object row by row but after iteration of resultset finished :
List<Map<String, String>> list = new ArrayList<Map<String, String>>();
ResultSetMetaData rsMetaData = rs.getMetaData();
while(rs.next()){
Map map = new HashMap();
for (int i = 1; i <= rsMetaData.getColumnCount(); i++) {
String key = rsMetaData.getColumnName(i);
String value = null;
if (rsmd.getColumnType(i) == java.sql.Types.VARCHAR) {
value = rs.getString(key);
} else if(rsmd.getColumnType(i)==java.sql.Types.BIGINT)
value = rs.getLong(key);
}
map.put(key, value);
}
list.add(map);
}
json.put(list);
Sort hash by key, return hash in Ruby
No, it is not (Ruby 1.9.x)
require 'benchmark'
h = {"a"=>1, "c"=>3, "b"=>2, "d"=>4}
many = 100_000
Benchmark.bm do |b|
GC.start
b.report("hash sort") do
many.times do
Hash[h.sort]
end
end
GC.start
b.report("keys sort") do
many.times do
nh = {}
h.keys.sort.each do |k|
nh[k] = h[k]
end
end
end
end
user system total real
hash sort 0.400000 0.000000 0.400000 ( 0.405588)
keys sort 0.250000 0.010000 0.260000 ( 0.260303)
For big hashes difference will grow up to 10x and more
What is the 'override' keyword in C++ used for?
Wikipedia says:
Method overriding, in object oriented programming, is a language feature that allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its superclasses or parent classes.
In detail, when you have an object foo that has a void hello() function:
class foo {
virtual void hello(); // Code : printf("Hello!");
}
A child of foo, will also have a hello() function:
class bar : foo {
// no functions in here but yet, you can call
// bar.hello()
}
However, you may want to print "Hello Bar!" when hello() function is being called from a bar object. You can do this using override
class bar : foo {
virtual void hello() override; // Code : printf("Hello Bar!");
}
Encode a FileStream to base64 with c#
When dealing with large streams, like a file sized over 4GB - you don't want to load the file into memory (as a Byte[]
) because not only is it very slow, but also may cause a crash as even in 64-bit processes a Byte[]
cannot exceed 2GB (or 4GB with gcAllowVeryLargeObjects
).
Fortunately there's a neat helper in .NET called ToBase64Transform
which processes a stream in chunks. For some reason Microsoft put it in System.Security.Cryptography
and it implements ICryptoTransform
(for use with CryptoStream
), but disregard that ("a rose by any other name...") just because you aren't performing any cryprographic tasks.
You use it with CryptoStream
like so:
using System.Security.Cryptography;
using System.IO;
//
using( FileStream inputFile = new FileStream( @"C:\VeryLargeFile.bin", FileMode.Open, FileAccess.Read, FileShare.None, bufferSize: 1024 * 1024, useAsync: true ) ) // When using `useAsync: true` you get better performance with buffers much larger than the default 4096 bytes.
using( CryptoStream base64Stream = new CryptoStream( inputFile, new ToBase64Transform(), CryptoStreamMode.Read ) )
using( FileStream outputFile = new FileStream( @"C:\VeryLargeBase64File.txt", FileMode.CreateNew, FileAccess.Write, FileShare.None, bufferSize: 1024 * 1024, useAsync: true ) )
{
await base64Stream.CopyToAsync( outputFile ).ConfigureAwait(false);
}
How to search a string in String array
If the array is sorted, you can use BinarySearch. This is a O(log n) operation, so it is faster as looping. If you need to apply multiple searches and speed is a concern, you could sort it (or a copy) before using it.
How to show full column content in a Spark Dataframe?
PYSPARK
In the below code, df
is the name of dataframe. 1st parameter is to show all rows in the dataframe dynamically rather than hardcoding a numeric value. The 2nd parameter will take care of displaying full column contents since the value is set as False
.
df.show(df.count(),False)
SCALA
In the below code, df
is the name of dataframe. 1st parameter is to show all rows in the dataframe dynamically rather than hardcoding a numeric value. The 2nd parameter will take care of displaying full column contents since the value is set as false
.
df.show(df.count().toInt,false)
How do I edit $PATH (.bash_profile) on OSX?
Determine which shell you're using by typing echo $SHELL
in Terminal.
Then open/create correct rc file. For Bash it's $HOME/.bash_profile
or $HOME/.bashrc
. For Z shell it's $HOME/.zshrc
.
Add this line to the file end:
export PATH="$PATH:/your/new/path"
To verify, refresh variables by restarting Terminal or typing source $HOME/.<rc file>
and then do echo $PATH
Scikit-learn: How to obtain True Positive, True Negative, False Positive and False Negative
I think both of the answers are not fully correct. For example, suppose that we have the following arrays;
y_actual = [1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0]
y_predic = [1, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0]
If we compute the FP, FN, TP and TN values manually, they should be as follows:
FP: 3
FN: 1
TP: 3
TN: 4
However, if we use the first answer, results are given as follows:
FP: 1
FN: 3
TP: 3
TN: 4
They are not correct, because in the first answer, False Positive should be where actual is 0, but the predicted is 1, not the opposite. It is also same for False Negative.
And, if we use the second answer, the results are computed as follows:
FP: 3
FN: 1
TP: 4
TN: 3
True Positive and True Negative numbers are not correct, they should be opposite.
Am I correct with my computations? Please let me know if I am missing something.
Docker error cannot delete docker container, conflict: unable to remove repository reference
There is a difference between docker images and docker containers. Check this SO Question.
In short, a container is a runnable instance of an image. which is why you cannot delete an image if there is a running container from that image. You just need to delete the container first.
docker ps -a # Lists containers (and tells you which images they are spun from)
docker images # Lists images
docker rm <container_id> # Removes a stopped container
docker rm -f <container_id> # Forces the removal of a running container (uses SIGKILL)
docker rmi <image_id> # Removes an image
# Will fail if there is a running instance of that image i.e. container
docker rmi -f <image_id> # Forces removal of image even if it is referenced in multiple repositories,
# i.e. same image id given multiple names/tags
# Will still fail if there is a docker container referencing image
Update for Docker 1.13+ [Since Jan 2017]
In Docker 1.13, we regrouped every command to sit under the logical object it’s interacting with
Basically, above commands could also be rewritten, more clearly, as:
docker container ls -a
docker image ls
docker container rm <container_id>
docker image rm <image_id>
Also, if you want to remove EVERYTHING you could use:
docker system prune -a
WARNING! This will remove:
- all stopped containers
- all networks not used by at least one container
- all unused images
- all build cache
Plotting lines connecting points
You can just pass a list of the two points you want to connect to plt.plot
. To make this easily expandable to as many points as you want, you could define a function like so.
import matplotlib.pyplot as plt
x=[-1 ,0.5 ,1,-0.5]
y=[ 0.5, 1, -0.5, -1]
plt.plot(x,y, 'ro')
def connectpoints(x,y,p1,p2):
x1, x2 = x[p1], x[p2]
y1, y2 = y[p1], y[p2]
plt.plot([x1,x2],[y1,y2],'k-')
connectpoints(x,y,0,1)
connectpoints(x,y,2,3)
plt.axis('equal')
plt.show()
Note, that function is a general function that can connect any two points in your list together.
To expand this to 2N points, assuming you always connect point i
to point i+1
, we can just put it in a for loop:
import numpy as np
for i in np.arange(0,len(x),2):
connectpoints(x,y,i,i+1)
In that case of always connecting point i
to point i+1
, you could simply do:
for i in np.arange(0,len(x),2):
plt.plot(x[i:i+2],y[i:i+2],'k-')
Finding row index containing maximum value using R
How about the following, where y is the name of your matrix and you are looking for the maximum in the entire matrix:
row(y)[y==max(y)]
if you want to extract the row:
y[row(y)[y==max(y)],] # this returns unsorted rows.
To return sorted rows use:
y[sort(row(y)[y==max(y)]),]
The advantage of this approach is that you can change the conditional inside to anything you need. Also, using col(y)
and location of the hanging comma you can also extract columns.
y[,col(y)[y==max(y)]]
To find just the row for the max in a particular column, say column 2 you could use:
seq(along=y[,2])[y[,2]==max(y[,2])]
again the conditional is flexible to look for different requirements.
See Phil Spector's excellent "An introduction to S and S-Plus" Chapter 5 for additional ideas.
How to load all modules in a folder?
Just import them by importlib and add them to __all__
(add
action is optional) in recurse in the __init__.py
of package.
/Foo
bar.py
spam.py
eggs.py
__init__.py
# __init__.py
import os
import importlib
pyfile_extes = ['py', ]
__all__ = [importlib.import_module('.%s' % filename, __package__) for filename in [os.path.splitext(i)[0] for i in os.listdir(os.path.dirname(__file__)) if os.path.splitext(i)[1] in pyfile_extes] if not filename.startswith('__')]
del os, importlib, pyfile_extes
How to activate virtualenv?
You forgot to do source bin/activate
where source is a executable name.
Struck me first few times as well, easy to think that manual is telling "execute this from root of the environment folder".
No need to make activate
executable via chmod
.
Showing data values on stacked bar chart in ggplot2
As hadley mentioned there are more effective ways of communicating your message than labels in stacked bar charts. In fact, stacked charts aren't very effective as the bars (each Category) doesn't share an axis so comparison is hard.
It's almost always better to use two graphs in these instances, sharing a common axis. In your example I'm assuming that you want to show overall total and then the proportions each Category contributed in a given year.
library(grid)
library(gridExtra)
library(plyr)
# create a new column with proportions
prop <- function(x) x/sum(x)
Data <- ddply(Data,"Year",transform,Share=prop(Frequency))
# create the component graphics
totals <- ggplot(Data,aes(Year,Frequency)) + geom_bar(fill="darkseagreen",stat="identity") +
xlab("") + labs(title = "Frequency totals in given Year")
proportion <- ggplot(Data, aes(x=Year,y=Share, group=Category, colour=Category))
+ geom_line() + scale_y_continuous(label=percent_format())+ theme(legend.position = "bottom") +
labs(title = "Proportion of total Frequency accounted by each Category in given Year")
# bring them together
grid.arrange(totals,proportion)
This will give you a 2 panel display like this:
If you want to add Frequency values a table is the best format.
Easiest way to convert month name to month number in JS ? (Jan = 01)
One more way to do the same
month1 = month1.toLowerCase();
var months = ["jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec"];
month1 = months.indexOf(month1);
How to check if a table contains an element in Lua?
I know this is an old post, but I wanted to add something for posterity.
The simple way of handling the issue that you have is to make another table, of value to key.
ie. you have 2 tables that have the same value, one pointing one direction, one pointing the other.
function addValue(key, value)
if (value == nil) then
removeKey(key)
return
end
_primaryTable[key] = value
_secodaryTable[value] = key
end
function removeKey(key)
local value = _primaryTable[key]
if (value == nil) then
return
end
_primaryTable[key] = nil
_secondaryTable[value] = nil
end
function getValue(key)
return _primaryTable[key]
end
function containsValue(value)
return _secondaryTable[value] ~= nil
end
You can then query the new table to see if it has the key 'element'. This prevents the need to iterate through every value of the other table.
If it turns out that you can't actually use the 'element' as a key, because it's not a string for example, then add a checksum or tostring
on it for example, and then use that as the key.
Why do you want to do this? If your tables are very large, the amount of time to iterate through every element will be significant, preventing you from doing it very often. The additional memory overhead will be relatively small, as it will be storing 2 pointers to the same object, rather than 2 copies of the same object.
If your tables are very small, then it will matter much less, infact it may even be faster to iterate than to have another map lookup.
The wording of the question however strongly suggests that you have a large number of items to deal with.
Use a JSON array with objects with javascript
Your question feels a little incomplete, but I think what you're looking for is a way of making your JSON accessible to your code:
if you have the JSON string as above then you'd just need to do this
var jsonObj = eval('[{"id":28,"Title":"Sweden"}, {"id":56,"Title":"USA"}, {"id":89,"Title":"England"}]');
then you can access these vars with something like jsonObj[0].id etc
Let me know if that's not what you were getting at and I'll try to help.
M
Twitter Bootstrap - full width navbar
I know I'm a bit late to the party, but I got around the issue by tweaking the CSS to have the width span 100%, and setting l/r margins to 0px;
#div_id
{
margin-left: 0px;
margin-right: 0px;
width: 100%;
}
How can I convert an HTML element to a canvas element?
Sorry, the browser won't render HTML into a canvas.
It would be a potential security risk if you could, as HTML can include content (in particular images and iframes) from third-party sites. If canvas
could turn HTML content into an image and then you read the image data, you could potentially extract privileged content from other sites.
To get a canvas from HTML, you'd have to basically write your own HTML renderer from scratch using drawImage
and fillText
, which is a potentially huge task. There's one such attempt here but it's a bit dodgy and a long way from complete. (It even attempts to parse the HTML/CSS from scratch, which I think is crazy! It'd be easier to start from a real DOM node with styles applied, and read the styling using getComputedStyle
and relative positions of parts of it using offsetTop
et al.)
remove legend title in ggplot
You were almost there : just add theme(legend.title=element_blank())
ggplot(df, aes(x, y, colour=g)) +
geom_line(stat="identity") +
theme(legend.position="bottom") +
theme(legend.title=element_blank())
This page on Cookbook for R gives plenty of details on how to customize legends.
How to Get the HTTP Post data in C#?
In my case because I assigned the post data to the header, this is how I get it:
protected void Page_Load(object sender, EventArgs e){
...
postValue = Request.Headers["Key"];
This is how I attached the value and key to the POST
:
var request = new NSMutableUrlRequest(url){
HttpMethod = "POST",
Headers = NSDictionary.FromObjectAndKey(FromObject(value), FromObject("key"))
};
webView.LoadRequest(request);
Can I access a form in the controller?
If you want to pass the form to the controller for validation purposes you can simply pass it as an argument to the method handling the submission. Use the form name, so for the original question it would be something like:
<button ng-click="submit(customerForm)">Save</button>
Git - fatal: Unable to create '/path/my_project/.git/index.lock': File exists
DO NOT USE the Atom platformio-atom-ide-terminal
Plugin to do this.
USE THE TERMINAL OF YOUR DISTRO DIRECTLY.
I kept getting this error while rebasing/squishing commits and didn't know why because I had done it before several times.
Didn't matter how many times I would delete the index.lock
file, every time it would fail.
Turns out it was because I was using the ATOM EDITOR terminal plugin. Once I used the terminal that ships with Ubuntu it worked like a charm.
Push Notifications in Android Platform
Android Cloud to Device Messaging Framework
Important: C2DM has been officially deprecated as of June 26, 2012. This means that C2DM has stopped accepting new users and quota requests. No new features will be added to C2DM. However, apps using C2DM will continue to work. Existing C2DM developers are encouraged to migrate to the new version of C2DM, called Google Cloud Messaging for Android (GCM). See the C2DM-to-GCM Migration document for more information. Developers must use GCM for new development.
Kindly check the following link:
http://developer.android.com/guide/google/gcm/index.html
Why can't a text column have a default value in MySQL?
I normally run sites on Linux, but I also develop on a local Windows machine. I've run into this problem many times and just fixed the tables when I encountered the problems. I installed an app yesterday to help someone out and of course ran into the problem again. So, I decided it was time to figure out what was going on - and found this thread. I really don't like the idea of changing the sql_mode of the server to an earlier mode (by default), so I came up with a simple (me thinks) solution.
This solution would of course require developers to wrap their table creation scripts to compensate for the MySQL issue running on Windows. You'll see similar concepts in dump files. One BIG caveat is that this could/will cause problems if partitioning is used.
// Store the current sql_mode
mysql_query("set @orig_mode = @@global.sql_mode");
// Set sql_mode to one that won't trigger errors...
mysql_query('set @@global.sql_mode = "MYSQL40"');
/**
* Do table creations here...
*/
// Change it back to original sql_mode
mysql_query('set @@global.sql_mode = @orig_mode');
That's about it.
How can I specify working directory for popen
subprocess.Popen
takes a cwd
argument to set the Current Working Directory; you'll also want to escape your backslashes ('d:\\test\\local'
), or use r'd:\test\local'
so that the backslashes aren't interpreted as escape sequences by Python. The way you have it written, the \t
part will be translated to a tab.
So, your new line should look like:
subprocess.Popen(r'c:\mytool\tool.exe', cwd=r'd:\test\local')
To use your Python script path as cwd, import os
and define cwd using this:
os.path.dirname(os.path.realpath(__file__))
How to upgrade scikit-learn package in anaconda
Updating a Specific Library - scikit-learn
:
Anaconda (conda
):
conda install scikit-learn
Pip Installs Packages (pip
):
pip install --upgrade scikit-learn
Verify Update:
conda list scikit-learn
It should now display the current (and desired) version of the scikit-learn
library.
For me personally, I tried using the conda
command to update the scikit-learn
library and it acted as if it were installing the latest version to then later discover (with an execution of the conda list scikit-learn
command) that it was the same version as previously and never updated (or recognized the update?). When I used the pip
command, it worked like a charm and correctly updated the scikit-learn
library to the latest version!
Hope this helps!
More in-depth details of latest version can be found here (be mindful this applies to the scikit-learn
library version of 0.22
):
find without recursion
If you look for POSIX compliant solution:
cd DirsRoot && find . -type f -print -o -name . -o -prune
-maxdepth is not POSIX compliant option.
JavaScript implementation of Gzip
Edit There appears to be a better LZW solution that handles Unicode strings correctly at http://pieroxy.net/blog/pages/lz-string/index.html (Thanks to pieroxy in the comments).
I don't know of any gzip implementations, but the jsolait library (the site seems to have gone away) has functions for LZW compression/decompression. The code is covered under the LGPL.
// LZW-compress a string
function lzw_encode(s) {
var dict = {};
var data = (s + "").split("");
var out = [];
var currChar;
var phrase = data[0];
var code = 256;
for (var i=1; i<data.length; i++) {
currChar=data[i];
if (dict[phrase + currChar] != null) {
phrase += currChar;
}
else {
out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
dict[phrase + currChar] = code;
code++;
phrase=currChar;
}
}
out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
for (var i=0; i<out.length; i++) {
out[i] = String.fromCharCode(out[i]);
}
return out.join("");
}
// Decompress an LZW-encoded string
function lzw_decode(s) {
var dict = {};
var data = (s + "").split("");
var currChar = data[0];
var oldPhrase = currChar;
var out = [currChar];
var code = 256;
var phrase;
for (var i=1; i<data.length; i++) {
var currCode = data[i].charCodeAt(0);
if (currCode < 256) {
phrase = data[i];
}
else {
phrase = dict[currCode] ? dict[currCode] : (oldPhrase + currChar);
}
out.push(phrase);
currChar = phrase.charAt(0);
dict[code] = oldPhrase + currChar;
code++;
oldPhrase = phrase;
}
return out.join("");
}
Get original URL referer with PHP?
Store it either in a cookie (if it's acceptable for your situation), or in a session variable.
session_start();
if ( !isset( $_SESSION["origURL"] ) )
$_SESSION["origURL"] = $_SERVER["HTTP_REFERER"];
How to stop a PowerShell script on the first error?
I came here looking for the same thing. $ErrorActionPreference="Stop" kills my shell immediately when I'd rather see the error message (pause) before it terminates. Falling back on my batch sensibilities:
IF %ERRORLEVEL% NEQ 0 pause & GOTO EOF
I found that this works pretty much the same for my particular ps1 script:
Import-PSSession $Session
If ($? -ne "True") {Pause; Exit}
Impersonate tag in Web.Config
You had the identity
node as a child of authentication
node. That was the issue. As in the example above, authentication
and identity
nodes must be children of the system.web
node
How do I set the time zone of MySQL?
Ancient question with one more suggestion:
If you've recently changed the timezone of the OS, e.g. via:
unlink /etc/localtime
ln -s /etc/usr/share/zoneinfo/US/Eastern /etc/localtime
... MySQL (or MariaDB) will not notice until you restart the db service:
service mysqld restart
(or)
service mariadb restart
jQuery: get parent tr for selected radio button
Try this.
You don't need to prefix attribute name by @
in jQuery selector. Use closest()
method to get the closest parent element matching the selector.
$("#MwDataList input[name=selectRadioGroup]:checked").closest('tr');
You can simplify your method like this
function getSelectedRowGuid() {
return GetRowGuid(
$("#MwDataList > input:radio[@name=selectRadioGroup]:checked :parent tr"));
}
closest()
- Gets the first element that matches the selector, beginning at the current element and progressing up through the DOM tree.
As a side note, the ids of the elements should be unique on the page so try to avoid having same ids for radio buttons which I can see in your markup. If you are not going to use the ids then just remove it from the markup.
Sorting arrays in javascript by object key value
This worked for me
var files=data.Contents;
files = files.sort(function(a,b){
return a.LastModified - b. LastModified;
});
OR use Lodash to sort the array
files = _.orderBy(files,'LastModified','asc');
How to parse XML in Bash?
This is really just an explaination of Yuzem's answer, but I didn't feel like this much editing should be done to someone else, and comments don't allow formatting, so...
rdom () { local IFS=\> ; read -d \< E C ;}
Let's call that "read_dom" instead of "rdom", space it out a bit and use longer variables:
read_dom () {
local IFS=\>
read -d \< ENTITY CONTENT
}
Okay so it defines a function called read_dom. The first line makes IFS (the input field separator) local to this function and changes it to >. That means that when you read data instead of automatically being split on space, tab or newlines it gets split on '>'. The next line says to read input from stdin, and instead of stopping at a newline, stop when you see a '<' character (the -d for deliminator flag). What is read is then split using the IFS and assigned to the variable ENTITY and CONTENT. So take the following:
<tag>value</tag>
The first call to read_dom
get an empty string (since the '<' is the first character). That gets split by IFS into just '', since there isn't a '>' character. Read then assigns an empty string to both variables. The second call gets the string 'tag>value'. That gets split then by the IFS into the two fields 'tag' and 'value'. Read then assigns the variables like: ENTITY=tag
and CONTENT=value
. The third call gets the string '/tag>'. That gets split by the IFS into the two fields '/tag' and ''. Read then assigns the variables like: ENTITY=/tag
and CONTENT=
. The fourth call will return a non-zero status because we've reached the end of file.
Now his while loop cleaned up a bit to match the above:
while read_dom; do
if [[ $ENTITY = "title" ]]; then
echo $CONTENT
exit
fi
done < xhtmlfile.xhtml > titleOfXHTMLPage.txt
The first line just says, "while the read_dom functionreturns a zero status, do the following." The second line checks if the entity we've just seen is "title". The next line echos the content of the tag. The four line exits. If it wasn't the title entity then the loop repeats on the sixth line. We redirect "xhtmlfile.xhtml" into standard input (for the read_dom
function) and redirect standard output to "titleOfXHTMLPage.txt" (the echo from earlier in the loop).
Now given the following (similar to what you get from listing a bucket on S3) for input.xml
:
<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<Name>sth-items</Name>
<IsTruncated>false</IsTruncated>
<Contents>
<Key>[email protected]</Key>
<LastModified>2011-07-25T22:23:04.000Z</LastModified>
<ETag>"0032a28286680abee71aed5d059c6a09"</ETag>
<Size>1785</Size>
<StorageClass>STANDARD</StorageClass>
</Contents>
</ListBucketResult>
and the following loop:
while read_dom; do
echo "$ENTITY => $CONTENT"
done < input.xml
You should get:
=>
ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/" =>
Name => sth-items
/Name =>
IsTruncated => false
/IsTruncated =>
Contents =>
Key => [email protected]
/Key =>
LastModified => 2011-07-25T22:23:04.000Z
/LastModified =>
ETag => "0032a28286680abee71aed5d059c6a09"
/ETag =>
Size => 1785
/Size =>
StorageClass => STANDARD
/StorageClass =>
/Contents =>
So if we wrote a while
loop like Yuzem's:
while read_dom; do
if [[ $ENTITY = "Key" ]] ; then
echo $CONTENT
fi
done < input.xml
We'd get a listing of all the files in the S3 bucket.
EDIT
If for some reason local IFS=\>
doesn't work for you and you set it globally, you should reset it at the end of the function like:
read_dom () {
ORIGINAL_IFS=$IFS
IFS=\>
read -d \< ENTITY CONTENT
IFS=$ORIGINAL_IFS
}
Otherwise, any line splitting you do later in the script will be messed up.
EDIT 2
To split out attribute name/value pairs you can augment the read_dom()
like so:
read_dom () {
local IFS=\>
read -d \< ENTITY CONTENT
local ret=$?
TAG_NAME=${ENTITY%% *}
ATTRIBUTES=${ENTITY#* }
return $ret
}
Then write your function to parse and get the data you want like this:
parse_dom () {
if [[ $TAG_NAME = "foo" ]] ; then
eval local $ATTRIBUTES
echo "foo size is: $size"
elif [[ $TAG_NAME = "bar" ]] ; then
eval local $ATTRIBUTES
echo "bar type is: $type"
fi
}
Then while you read_dom
call parse_dom
:
while read_dom; do
parse_dom
done
Then given the following example markup:
<example>
<bar size="bar_size" type="metal">bars content</bar>
<foo size="1789" type="unknown">foos content</foo>
</example>
You should get this output:
$ cat example.xml | ./bash_xml.sh
bar type is: metal
foo size is: 1789
EDIT 3 another user said they were having problems with it in FreeBSD and suggested saving the exit status from read and returning it at the end of read_dom like:
read_dom () {
local IFS=\>
read -d \< ENTITY CONTENT
local RET=$?
TAG_NAME=${ENTITY%% *}
ATTRIBUTES=${ENTITY#* }
return $RET
}
I don't see any reason why that shouldn't work
Oracle DB : java.sql.SQLException: Closed Connection
It means the connection was successfully established at some point, but when you tried to commit right there, the connection was no longer open. The parameters you mentioned sound like connection pool settings. If so, they're unrelated to this problem. The most likely cause is a firewall between you and the database that is killing connections after a certain amount of idle time. The most common fix is to make your connection pool run a validation query when a connection is checked out from it. This will immediately identify and evict dead connnections, ensuring that you only get good connections out of the pool.
Receive result from DialogFragment
In my case I needed to pass arguments to a targetFragment. But I got exception "Fragment already active". So I declared an Interface in my DialogFragment which parentFragment implemented. When parentFragment started a DialogFragment , it set itself as TargetFragment. Then in DialogFragment I called
((Interface)getTargetFragment()).onSomething(selectedListPosition);
Java 8 Stream API to find Unique Object matching a property value
Instead of using a collector try using findFirst
or findAny
.
Optional<Person> matchingObject = objects.stream().
filter(p -> p.email().equals("testemail")).
findFirst();
This returns an Optional
since the list might not contain that object.
If you're sure that the list always contains that person you can call:
Person person = matchingObject.get();
Be careful though! get
throws NoSuchElementException
if no value is present. Therefore it is strongly advised that you first ensure that the value is present (either with isPresent
or better, use ifPresent
, map
, orElse
or any of the other alternatives found in the Optional
class).
If you're okay with a null
reference if there is no such person, then:
Person person = matchingObject.orElse(null);
If possible, I would try to avoid going with the null
reference route though. Other alternatives methods in the Optional class (ifPresent
, map
etc) can solve many use cases. Where I have found myself using orElse(null)
is only when I have existing code that was designed to accept null
references in some cases.
Optionals have other useful methods as well. Take a look at Optional javadoc.
How do I sort a dictionary by value?
Try the following approach. Let us define a dictionary called mydict with the following data:
mydict = {'carl':40,
'alan':2,
'bob':1,
'danny':3}
If one wanted to sort the dictionary by keys, one could do something like:
for key in sorted(mydict.iterkeys()):
print "%s: %s" % (key, mydict[key])
This should return the following output:
alan: 2
bob: 1
carl: 40
danny: 3
On the other hand, if one wanted to sort a dictionary by value (as is asked in the question), one could do the following:
for key, value in sorted(mydict.iteritems(), key=lambda (k,v): (v,k)):
print "%s: %s" % (key, value)
The result of this command (sorting the dictionary by value) should return the following:
bob: 1
alan: 2
danny: 3
carl: 40
Force SSL/https using .htaccess and mod_rewrite
I found a mod_rewrite
solution that works well for both proxied and unproxied servers.
If you are using CloudFlare, AWS Elastic Load Balancing, Heroku, OpenShift or any other Cloud/PaaS solution and you are experiencing redirect loops with normal HTTPS redirects, try the following snippet instead.
RewriteEngine On
# If we receive a forwarded http request from a proxy...
RewriteCond %{HTTP:X-Forwarded-Proto} =http [OR]
# ...or just a plain old http request directly from the client
RewriteCond %{HTTP:X-Forwarded-Proto} =""
RewriteCond %{HTTPS} !=on
# Redirect to https version
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
How can I decrease the size of Ratingbar?
You can set it in the XML code for the RatingBar
, use scaleX
and scaleY
to adjust accordingly. "1.0" would be the normal size, and anything in the ".0" will reduce it, also anything greater than "1.0" will increase it.
<RatingBar
android:id="@+id/ratingBar1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleX="0.5"
android:scaleY="0.5" />
SPA best practices for authentication and session management
This question has been addressed, in a slightly different form, at length, here:
RESTful Authentication
But this addresses it from the server-side. Let's look at this from the client-side. Before we do that, though, there's an important prelude:
Javascript Crypto is Hopeless
Matasano's article on this is famous, but the lessons contained therein are pretty important:
https://www.nccgroup.trust/us/about-us/newsroom-and-events/blog/2011/august/javascript-cryptography-considered-harmful/
To summarize:
- A man-in-the-middle attack can trivially replace your crypto code with
<script>
function hash_algorithm(password){ lol_nope_send_it_to_me_instead(password); }</script>
- A man-in-the-middle attack is trivial against a page that serves any resource over a non-SSL connection.
- Once you have SSL, you're using real crypto anyways.
And to add a corollary of my own:
- A successful XSS attack can result in an attacker executing code on your client's browser, even if you're using SSL - so even if you've got every hatch battened down, your browser crypto can still fail if your attacker finds a way to execute any javascript code on someone else's browser.
This renders a lot of RESTful authentication schemes impossible or silly if you're intending to use a JavaScript client. Let's look!
HTTP Basic Auth
First and foremost, HTTP Basic Auth. The simplest of schemes: simply pass a name and password with every request.
This, of course, absolutely requires SSL, because you're passing a Base64 (reversibly) encoded name and password with every request. Anybody listening on the line could extract username and password trivially. Most of the "Basic Auth is insecure" arguments come from a place of "Basic Auth over HTTP" which is an awful idea.
The browser provides baked-in HTTP Basic Auth support, but it is ugly as sin and you probably shouldn't use it for your app. The alternative, though, is to stash username and password in JavaScript.
This is the most RESTful solution. The server requires no knowledge of state whatsoever and authenticates every individual interaction with the user. Some REST enthusiasts (mostly strawmen) insist that maintaining any sort of state is heresy and will froth at the mouth if you think of any other authentication method. There are theoretical benefits to this sort of standards-compliance - it's supported by Apache out of the box - you could store your objects as files in folders protected by .htaccess files if your heart desired!
The problem? You are caching on the client-side a username and password. This gives evil.ru a better crack at it - even the most basic of XSS vulnerabilities could result in the client beaming his username and password to an evil server. You could try to alleviate this risk by hashing and salting the password, but remember: JavaScript Crypto is Hopeless. You could alleviate this risk by leaving it up to the Browser's Basic Auth support, but.. ugly as sin, as mentioned earlier.
HTTP Digest Auth
Is Digest authentication possible with jQuery?
A more "secure" auth, this is a request/response hash challenge. Except JavaScript Crypto is Hopeless, so it only works over SSL and you still have to cache the username and password on the client side, making it more complicated than HTTP Basic Auth but no more secure.
Query Authentication with Additional Signature Parameters.
Another more "secure" auth, where you encrypt your parameters with nonce and timing data (to protect against repeat and timing attacks) and send the. One of the best examples of this is the OAuth 1.0 protocol, which is, as far as I know, a pretty stonking way to implement authentication on a REST server.
http://tools.ietf.org/html/rfc5849
Oh, but there aren't any OAuth 1.0 clients for JavaScript. Why?
JavaScript Crypto is Hopeless, remember. JavaScript can't participate in OAuth 1.0 without SSL, and you still have to store the client's username and password locally - which puts this in the same category as Digest Auth - it's more complicated than HTTP Basic Auth but it's no more secure.
Token
The user sends a username and password, and in exchange gets a token that can be used to authenticate requests.
This is marginally more secure than HTTP Basic Auth, because as soon as the username/password transaction is complete you can discard the sensitive data. It's also less RESTful, as tokens constitute "state" and make the server implementation more complicated.
SSL Still
The rub though, is that you still have to send that initial username and password to get a token. Sensitive information still touches your compromisable JavaScript.
To protect your user's credentials, you still need to keep attackers out of your JavaScript, and you still need to send a username and password over the wire. SSL Required.
Token Expiry
It's common to enforce token policies like "hey, when this token has been around too long, discard it and make the user authenticate again." or "I'm pretty sure that the only IP address allowed to use this token is XXX.XXX.XXX.XXX
". Many of these policies are pretty good ideas.
Firesheeping
However, using a token Without SSL is still vulnerable to an attack called 'sidejacking': http://codebutler.github.io/firesheep/
The attacker doesn't get your user's credentials, but they can still pretend to be your user, which can be pretty bad.
tl;dr: Sending unencrypted tokens over the wire means that attackers can easily nab those tokens and pretend to be your user. FireSheep is a program that makes this very easy.
A Separate, More Secure Zone
The larger the application that you're running, the harder it is to absolutely ensure that they won't be able to inject some code that changes how you process sensitive data. Do you absolutely trust your CDN? Your advertisers? Your own code base?
Common for credit card details and less common for username and password - some implementers keep 'sensitive data entry' on a separate page from the rest of their application, a page that can be tightly controlled and locked down as best as possible, preferably one that is difficult to phish users with.
Cookie (just means Token)
It is possible (and common) to put the authentication token in a cookie. This doesn't change any of the properties of auth with the token, it's more of a convenience thing. All of the previous arguments still apply.
Session (still just means Token)
Session Auth is just Token authentication, but with a few differences that make it seem like a slightly different thing:
- Users start with an unauthenticated token.
- The backend maintains a 'state' object that is tied to a user's token.
- The token is provided in a cookie.
- The application environment abstracts the details away from you.
Aside from that, though, it's no different from Token Auth, really.
This wanders even further from a RESTful implementation - with state objects you're going further and further down the path of plain ol' RPC on a stateful server.
OAuth 2.0
OAuth 2.0 looks at the problem of "How does Software A give Software B access to User X's data without Software B having access to User X's login credentials."
The implementation is very much just a standard way for a user to get a token, and then for a third party service to go "yep, this user and this token match, and you can get some of their data from us now."
Fundamentally, though, OAuth 2.0 is just a token protocol. It exhibits the same properties as other token protocols - you still need SSL to protect those tokens - it just changes up how those tokens are generated.
There are two ways that OAuth 2.0 can help you:
- Providing Authentication/Information to Others
- Getting Authentication/Information from Others
But when it comes down to it, you're just... using tokens.
Back to your question
So, the question that you're asking is "should I store my token in a cookie and have my environment's automatic session management take care of the details, or should I store my token in Javascript and handle those details myself?"
And the answer is: do whatever makes you happy.
The thing about automatic session management, though, is that there's a lot of magic happening behind the scenes for you. Often it's nicer to be in control of those details yourself.
I am 21 so SSL is yes
The other answer is: Use https for everything or brigands will steal your users' passwords and tokens.
jQuery show/hide not working
if (grid.selectedKeyNames().length > 0) {
$('#btnRemoveFromList').show();
} else {
$('#btnRemoveFromList').hide();
}
}
()
- calls the method
no parentheses - returns the property
How to subtract one month using moment.js?
For substracting in moment.js:
moment().subtract(1, 'months').format('MMM YYYY');
Documentation:
http://momentjs.com/docs/#/manipulating/subtract/
Before version 2.8.0, the moment#subtract(String, Number) syntax was
also supported. It has been deprecated in favor of
moment#subtract(Number, String).
moment().subtract('seconds', 1); // Deprecated in 2.8.0
moment().subtract(1, 'seconds');
As of 2.12.0 when decimal values are passed for days and months, they
are rounded to the nearest integer. Weeks, quarters, and years are
converted to days or months, and then rounded to the nearest integer.
moment().subtract(1.5, 'months') == moment().subtract(2, 'months')
moment().subtract(.7, 'years') == moment().subtract(8, 'months') //.7*12 = 8.4, rounded to 8
How to check empty DataTable
Don't use rows.Count. That's asking for how many rows exist. If there are many, it will take some time to count them. All you really want to know is "is there at least one?" You don't care if there are 10 or 1000 or a billion. You just want to know if there is at least one. If I give you a box and ask you if there are any marbles in it, will you dump the box on the table and start counting? Of course not. Using LINQ, you might think that this would work:
bool hasRows = dataTable1.Rows.Any()
But unfortunately, DataRowCollection
does not implement IEnumerable
.
So instead, try this:
bool hasRows = dataTable1.Rows.GetEnumerator().MoveNext()
You will of course need to check if the dataTable1 is null first. if it's not, this will tell you if there are any rows without enumerating the whole lot.
How to call a REST web service API from JavaScript?
I think add if (this.readyState == 4 && this.status == 200) to wait is better:
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
// Typical action to be performed when the document is ready:
var response = xhttp.responseText;
console.log("ok"+response);
}
};
xhttp.open("GET", "your url", true);
xhttp.send();