Tutorial by Examples: l

There is a complementary function for filter in the itertools-module: Python 2.x2.0.1 # not recommended in real use but keeps the example valid for python 2.x and python 3.x from itertools import ifilterfalse as filterfalse Python 3.x3.0.0 from itertools import filterfalse which works...

First, install Node.js for your platform. In this example we'll create an HTTP server listening on port 1337, which sends Hello, World! to the browser. Note that, instead of using port 1337, you can use any port number of your choice which is currently not in use by any other service. The http mod...

[0-9] and \d are equivalent patterns (unless your Regex engine is unicode-aware and \d also matches things like ②). They will both match a single digit character so you can use whichever notation you find more readable. Create a string of the pattern you wish to match. If using the \d notation, you...

Type the following code into your terminal, then press Enter: echo "Hello World" This will produce the following output: Hello World

Exponentiation can be used by using the builtin pow-function or the ** operator: 2 ** 3 # 8 pow(2, 3) # 8 For most (all in Python 2.x) arithmetic operations the result's type will be that of the wider operand. This is not true for **; the following cases are exceptions from this rule: B...

The math-module contains another math.pow() function. The difference to the builtin pow()-function or ** operator is that the result is always a float: import math math.pow(2, 2) # 4.0 math.pow(-2., 2) # 4.0 Which excludes computations with complex inputs: math.pow(2, 2+0j) TypeErro...

Both the math and cmath-module contain the Euler number: e and using it with the builtin pow()-function or **-operator works mostly like math.exp(): import math math.e ** 2 # 7.3890560989306495 math.exp(2) # 7.38905609893065 import cmath cmath.e ** 2 # 7.3890560989306495 cmath.exp(2) # (...

The math module contains the expm1()-function that can compute the expression math.e ** x - 1 for very small x with higher precision than math.exp(x) or cmath.exp(x) would allow: import math print(math.e ** 1e-3 - 1) # 0.0010005001667083846 print(math.exp(1e-3) - 1) # 0.0010005001667083846 p...

Supposing you have a class that stores purely integer values: class Integer(object): def __init__(self, value): self.value = int(value) # Cast to an integer def __repr__(self): return '{cls}({val})'.format(cls=self.__class__.__name__, ...

A basic Employees table, containing an ID, and the employee's first and last name along with their phone number can be created using CREATE TABLE Employees( Id int identity(1,1) primary key not null, FName varchar(20) not null, LName varchar(20) not null, PhoneNumber varchar(10)...

Click the Run button in the toolbar (or press ⌘R) to build & run your project. Click Stop (or press ⌘.) to stop execution.   Click & hold to see the other actions, Test (⌘U), Profile (⌘I), and Analyze (⇧⌘B). Hold down modifier keys ⌥ option, ⇧ shift, and ⌃ control for more variants.  ...

A submodule references a specific commit in another repository. To check out the exact state that is referenced for all submodules, run git submodule update --recursive Sometimes instead of using the state that is referenced you want to update to your local checkout to the latest state of that s...

You can have multiple versions of Xcode installed at the same time (including beta versions). Simply rename the application in Finder to avoid conflicts. Note: Installing Xcode from the App Store will tend to overwrite an existing version on your machine. You can also install Xcode from a direct ...

CREATE TABLE HR_EMPLOYEES ( PersonID int, LastName VARCHAR(30), FirstName VARCHAR(30), Position VARCHAR(30) ); CREATE TABLE FINANCE_EMPLOYEES ( PersonID INT, LastName VARCHAR(30), FirstName VARCHAR(30), Position VARCHAR(30) ); Let's say we want to ...

You can list existing git aliases using --get-regexp: $ git config --get-regexp '^alias\.' Searching aliases To search aliases, add the following to your .gitconfig under [alias]: aliases = !git config --list | grep ^alias\\. | cut -c 7- | grep -Ei --color \"$1\" "#" The...

All built-in collections in Python implement a way to check element membership using in. List alist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 5 in alist # True 10 in alist # False Tuple atuple = ('0', '1', '2', '3', '4') 4 in atuple # False '4' in atuple # True String astring = 'i am a s...

list and tuple have an index-method to get the position of the element: alist = [10, 16, 26, 5, 2, 19, 105, 26] # search for 16 in the list alist.index(16) # 1 alist[1] # 16 alist.index(15) ValueError: 15 is not in list But only returns the position of the first found element: ...

dict have no builtin method for searching a value or key because dictionaries are unordered. You can create a function that gets the key (or keys) for a specified value: def getKeysForValue(dictionary, value): foundkeys = [] for keys in dictionary: if dictionary[key] == value: ...

Sorted sequences allow the use of faster searching algorithms: bisect.bisect_left()1: import bisect def index_sorted(sorted_seq, value): """Locate the leftmost value exactly equal to x or raise a ValueError""" i = bisect.bisect_left(sorted_seq, value) ...

Let's say we have a query of the remaining horsemen that needs to populate a Person class. NameBornResidenceDaniel Dennett1942United States of AmericaSam Harris1967United States of AmericaRichard Dawkins1941United Kingdom public class Person { public string Name { get; set; } public int...