Python

Python Subprocess Library is a A single executable, or sequence of executable and arguments. Learn More about it here. Parameter DetailsA single executable, or sequence of executable and arguments – ,args’ls’ [‘ls’, ‘-la’]Run under a shell? The default shell to on POSIX.shell/bin/shWorking directory of the child process.cwd Python Subprocess Library: More flexibility with Popen Using … Read more

Parsing Command Line arguments allow both the user and other programs to run the Python file passing it data as it starts. Learn more here. Most command line tools rely on arguments passed to the program upon its execution. Instead of prompting for input, these programs expect data or specific flags (which become booleans) to … Read more

pip: PyPI Package Manager: pip is the most widely-used package manager for the Python Package Index, installed by default with recent versions of Python. PyPI Package Manager: Install Packages To install the latest version of a package named SomePackage: $ pip install SomePackage To install a specific version of a package: $ pip install SomePackage==1.0.4 … Read more

Usage of “pip” module: PyPI Package Manager is helpful when you may need to use pip package manager inside python eg. when some imports may raise. ImportError and you want to handle the exception. If you unpack on Windows Python_root/Scripts/pip.exeinside is stored main.py file, where main class from pip package is imported. This means pip … Read more

Creating Python packages Introduction Every package requires a setup.py file which describes the package. Consider the following directory structure for a simple package: +– package_name| |+– init.py+– setup.py The init.py contains only the line def foo(): return 100. The following setup.py will define the package: from setuptools import setupsetup(name=’package_name’, # package nameversion=’0.1′, # versiondescription=’Package Description’, … Read more

Checking Path Existence and Permissions Parameter Details os.F_OK Value to pass as the mode parameter of access() to test the existence of path. os.R_OK Value to include in the mode parameter of access() to test the readability of path. os.W_OK Value to include in the mode parameter of access() to test the writability of path. … Read more

The name special variable is used to check whether a file has been imported as a module or not, and to identify a function, class, module object by their name attribute. name == ‘main‘ The special variable name is not set by the user. It is mostly used to check whether or not the module … Read more

While Python’s context managers are widely used, few understand the purpose behind their use. These statements, commonly used with reading and writing files, assist the application in conserving system memory and improve resource management by ensuring specific resources are only in use for certain processes. This topic explains and demonstrates the use of Python’s context … Read more

Copying data CoSpy a dictionary A dictionary object has the method copy. It performs a shallow copy of the dictionary. d1 = {1:[]}d2 = d1.copy()d1 is d2 Falsed1[1] is d2[1]True Performing a shallow copy A shallow copy is a copy of a collection without performing a copy of its elements. import copyc = [[1,2]]d = … Read more

Regular Expressions (Regex): Python makes regular expressions available through the re module. Regular expressions are combinations of characters that are interpreted as rules for matching substrings. For instance, the expression ‘amount\D+\d+’ will match any string composed by the word amount plus an integral number, separated by one or more non-digits, such as:amount=100, amount is 3, … Read more

The Print Function Print basics In Python 3 and higher, print is a function rather than a keyword. print(‘hello world!’) out: hello world! foo = 1bar = ‘bar’baz = 3.14print(foo)out: 1 print(bar)out: bar print(baz)out: 3.14 You can also pass a number of parameters to print: print(foo, bar, baz) out: 1 bar 3.14 Another way to … Read more

Counting: Counting all occurrence of all items in aniterable: collections.Counter from collections import Counterc = Counter([“a”, “b”, “c”, “d”, “a”, “b”, “a”, “c”, “d”])cOut: Counter({‘a’: 3, ‘b’: 2, ‘c’: 2, ‘d’: 2}) c[“a”]Out: 3c[7] # not in the list (7 occurred 0 times!) Out: 0 The collections.Counter can be used for any iterable and counts … Read more

Exponentiation – Exponentiation can be used by using the builtin pow-function or the ** operator. Learn More about it here. Exponentiation using builtins: ** and pow() Exponentiation can be used by using the builtin pow-function or the ** operator: 2**3 # 8pow(2, 3) # 8 For most (all in Python 2.x) arithmetic operations the result’s … Read more

Searching – All built-in collections in Python implement a way to check element membership using in.. Learn More here. Searching for an element All built-in collections in Python implement a way to check element membership using in. Listalist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]5 in alist # True10 in alist … Read more

Map Function- Parameter Details function function for mapping (must take as many parameters as there are iterables) (positional-only) iterable the function is applied to each element of the iterable (positional-only) *additional_iterables see iterable, but as many as you like (optional, positional-only) Basic use of Map Function, itertools.imap and future_builtins.map The map function is the simplest … Read more

Reduce function that is used for reducing the iterable (must take two arguments). (positional-only). Learn More about it here. Parameter Details function function that is used for reducing the iterable (must take two arguments). (positional-only) iterable iterable that’s going to be reduced. (positional-only) initializer start-value of the reduction. (optional, positional-only) Overview No import neededNo import … Read more

Generators Generators are lazy iterators created by generator functions (using yield) or generator expressions (using (an_expression for x in an_iterator)). Generators: Introduction Generator expressions are similar to list, dictionary and set comprehensions, but are enclosed with parentheses. The parentheses do not have to be present when they are used as the sole argument for a … Read more

graph-tool The python tools can be used to generate graph. Learn more about the different ways in which you can use the graph-tool in python. graph-tool: PyDotPlus PyDotPlus is an improved version of the old pydot project that provides a Python Interface to Graphviz’s Dot language. Installation For the latest stable version: pip install pydotplus … Read more

Plotting with Matplotlib Matplotlib (https://matplotlib.org/) is a library for 2D plotting based on NumPy. Here are some basic examples. More examples can be found in the official documentation (https://matplotlib.org/2.0.2/gallery.html and https://matplotlib.org/2.0.2/examples/index.html) Plotting with Matplotlib: Plots with Common X-axis but di erent Y-axis :Using twinx() In this example, we will plot a sine curve and a … Read more

Indexing and Slicing is another important part of Python programming as it helps in managing different objects involved in functions. Learn more here. Paramer DescriptionThe object that you want to extract a “sub-object” fromobjThe index of that you want the sub-object to start from (keep in mind that Python is zero-indexed,objstartmeaning that the first item … Read more