Tutorial by Examples: n

The modifier that allows using whitespace inside some parts of the pattern to format it for better readability and to allow comments starting with #: /(?x)^ # start of string (?=\D*\d) # the string should contain at least 1 digit (?!\d+$) # the string cannot consist of digi...

The UNICODE modifier, usually expressed as u (PHP, Python) or U (Java), makes the regex engine treat the pattern and the input string as Unicode strings and patterns, make the pattern shorthand classes like \w, \d, \s, etc. Unicode-aware. /\A\p{L}+\z/u is a PHP regex to match strings that consis...

The PCRE-compliant PCRE_DOLLAR_ENDONLY modifier that makes the $ anchor match at the very end of the string (excluding the position before the final newline in the string). /^\d+$/D is equal to /^\d+\z/ and matches a whole string that consists of 1 or more digits and will not match "123...

Another PCRE-compliant modifier expressed with /A modifier. If this modifier is set, the pattern is forced to be "anchored", that is, it is constrained to match only at the start of the string which is being searched (the "subject string"). This effect can also be achieved by ap...

The PCRE-compliant PCRE_UNGREEDY flag expressed with /U. It switches greediness inside a pattern: /a.*?b/U = /a.*b/ and vice versa.

One more PCRE modifier that allows the use of duplicate named groups. NOTE: only inline version is supported - (?J), and must be placed at the start of the pattern. If you use /(?J)\w+-(?:new-(?<val>\w+)|\d+-empty-(?<val>[^-]+)-collection)/ the "val" group values will be ...

%storemagic stores variables and macros on IPython's database. To automatically restore stored variables at startup add this to ipython_config.py: c.StoreMagic.autorestore = True Example: In [1]: l = ['hello',10,'world'] In [2]: %store l In [3]: exit (IPython session is closed and started...

You may install Composer locally, as part of your project, or globally as a system wide executable. Locally To install, run these commands in your terminal. php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');" # to check the validity of the downloaded installer, ch...

Dojo provides us various themes like tundra, claro etc. Load themes using link tag in your HTML page pointing to Google CDN.

numpy.dot can be used to multiply a list of vectors by a matrix but the orientation of the vectors must be vertical so that a list of eight two component vectors appears like two eight components vectors: >>> a array([[ 1., 2.], [ 3., 1.]]) >>> b array([[ 1., 2., ...

filePath = "file.csv" data = np.genfromtxt(filePath) Many options are supported, see official documentation for full list: data = np.genfromtxt(filePath, dtype='float', delimiter=';', skip_header=1, usecols=(0,1,3) )

I have some data analysis done on some data and have many 'non-coding' people on the team, who have similar data like mine, and have similar analysis requirements. In such cases, I can build a web application with shiny, which takes in user specific input data files, and generate analyses. I ...

A nested loop is a loop within a loop, an inner loop within the body of an outer one. How this works is that the first pass of the outer loop triggers the inner loop, which executes to completion. Then the second pass of the outer loop triggers the inner loop again. This repeats until the outer loop...

With the bind command it is possible to define custom key bindings. The next example bind an Alt + w to >/dev/null 2>&1: bind '"\ew"':"\" >/dev/null 2>&1\"" If you want to execute the line immediately add \C-m (Enter) to it: bind '"\ew&quo...

When a Java virtual machine starts, it needs to know how big to make the Heap, and the default size for thread stacks. These can be specified using command-line options on the java command. For versions of Java prior to Java 8, you can also specify the size of the PermGen region of the Heap. Note...

Searching git log using some string in log: git log [options] --grep "search_string" Example: git log --all --grep "removed file" Will search for removed file string in all logs in all branches. Starting from git 2.4+, the search can be inverted using the --invert-grep...

Reading invalid UTF-8 When reading UTF-8 encoded data, it is important to be aware of the fact the UTF-8 encoded data can be invalid or malformed. Such data should usually not be accepted by your program (unless you know what you are doing). When unexpectedly encountering malformed data, different ...

The arrayref for @foo is \@foo. This is handy if you need to pass an array and other things to a subroutine. Passing @foo is like passing multiple scalars. But passing \@foo is a single scalar. Inside the subroutine: xyz(\@foo, 123); ... sub xyz { my ($arr, $etc) = @_; print $arr-&g...

Merges two collections (without removing duplicates) List<int> foo = new List<int> { 1, 2, 3 }; List<int> bar = new List<int> { 3, 4, 5 }; // Through Enumerable static class var result = Enumerable.Concat(foo, bar).ToList(); // 1,2,3,3,4,5 // Through extension method...

Objective C NSURL *url = [NSURL URLWithString:@"YOUR URL"]; AVPlayer *player = [AVPlayer playerWithURL:videoURL]; AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:player]; playerLayer.frame = self.view.bounds; [self.view.layer addSublayer:playerLayer]; [player play];...