Tutorial by Examples: p

Some websites don’t like to be scraped. In these cases you may need to simulate a real user working with a browser. Selenium launches and controls a web browser. from selenium import webdriver browser = webdriver.Firefox() # launch firefox browser browser.get('http://stackoverflow.com/questi...

The Abstract Factory Pattern is a creational design pattern that can be used to define specific instances or classes without having to specify the exact object that is being created. function Car() { this.name = "Car"; this.wheels = 4; } function Truck() { this.name = "Truck"; ...

/* PL/SQL is a core Oracle Database technology, allowing you to build clean, secure, optimized APIs to SQL and business logic. */ set serveroutput on BEGIN DBMS_OUTPUT.PUT_LINE ('Hello World!'); END;

Detailed instructions on getting pyspark set up or installed.

Limit root (and any other SUPER-privileged user) to GRANT ... TO root@localhost ... That prevents access from other servers. You should hand out SUPER to very few people, and they should be aware of their responsibility. The application should not have SUPER. Limit application logins to the one...

Note: Browsers are in the process of adding a built-in context.ellipse drawing command, but this command is not universally adopted (notably not in IE). The methods below work in all browsers. Draw an ellipse given it's desired top-left coordinate: // draws an ellipse based on x,y being top-left...

A regular polygon has all sides equal length. // Usage: drawRegularPolygon(3,25,75,50,6,'gray','red',0); drawRegularPolygon(5,25,150,50,6,'gray','gold',0); drawRegularPolygon(6,25,225,50,6,'gray','lightblue',0); drawRegularPolygon(10,25,300,50,6,'gray','lightgreen',0); function drawRegular...

adb devices Is your phone displaying? If not, enable developer mode on your phone, and connect it by USB. adb reverse tcp:8081 tcp:8081 : In order to link correctly your phone and that React-Native recognize him during build. (NOTE:Android Version 5 or above.) react-native run-andr...

Before you start the cherry-pick process, you can check if the commit you want to cherry-pick already exists in the target branch, in which case you don't have to do anything. git branch --contains <commit> lists local branches that contain the specified commit. git branch -r --contains <...

Bounded type parameters allow you to set restrictions on generic type arguments: class SomeClass { } class Demo<T extends SomeClass> { } But a type parameter can only bind to a single class type. An interface type can be bound to a type that already had a binding. This is achieve...

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...

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 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...

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., ...