Tutorial by Examples: e

Create a Java class which extends org.apache.hadoop.hive.ql.exec.hive.UDAF Create an inner class which implements UDAFEvaluator Implement five methods init() – This method initializes the evaluator and resets its internal state. We are using new Column() in the code below to indicate th...

A regex pattern where a DOTALL modifier (in most regex flavors expressed with s) changes the behavior of . enabling it to match a newline (LF) symbol: /cat (.*?) dog/s This Perl-style regex will match a string like "cat fled from\na dog" capturing "fled from\na" into Group 1....

Another example is a MULTILINE modifier (usually expressed with m flag (not in Oniguruma (e.g. Ruby) that uses m to denote a DOTALL modifier)) that makes ^ and $ anchors match the start/end of a line, not the start/end of the whole string. /^My Line \d+$/gm will find all lines that start with My...

The common modifier to ignore case is i: /fog/i will match Fog, foG, etc. The inline version of the modifier looks like (?i). Notes: In Java, by default, case-insensitive matching assumes that only characters in the US-ASCII charset are being matched. Unicode-aware case-insensitive matching c...

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...

This is a .NET regex specific modifier expressed with n. When used, unnamed groups (like (\d+)) are not captured. Only valid captures are explicitly named groups (e.g. (?<name> subexpression)). (?n)(\d+)-(\w+)-(?<id>\w+) will match the whole 123-1_abc-00098, but (\d+) and (\w+) won't...

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 ...

A PCRE modifier that causes an error if any backslash in a pattern is followed by a letter that has no special meaning. By default, a backslash followed by a letter with no special meaning is treated as a literal. E.g. /big\y/ will match bigy, but /big\y/X will throw an exception. Inline v...

%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...

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...