Python Tutorial

Introduction Python Features Python Applications System requirements for Python Python Installation Python Examples Python Basics Python Indentation Python Variables Python Data Types Python IDE Python Keywords Python Operators Python Comments Python Pass Statement

Python Conditional Statements

Python if Statement Python elif Statement Python If-else statement Python Switch Case

Python Loops

Python for loop Python while loop Python Break Statement Python Continue Statement Python Goto Statement

Python Arrays

Python Array Python Matrix

Python Strings

Python Strings Python Regex

Python Built-in Data Structure

Python Lists Python Tuples Python Lists vs Tuples Python Dictionary Python Sets

Python Functions

Python Function Python min() function Python max() function Python User-define Functions Python Built-in Functions Python Recursion Anonymous/Lambda Function in Python python apply() Function Python lambda() Function

Python File Handling

Python File Handling Python Read CSV Python Write CSV Python Read Excel Python Write Excel Python Read Text File Python Write Text File Read JSON File in Python

Python Exception Handling

Python Exception Handling Python Errors and exceptions Python Assert

Python OOPs Concept

OOPs Concepts in Python Classes & Objects in Python Inheritance in Python Polymorphism in Python Python Encapsulation Python Constructor Python Super function Python Static Method Static Variables in Python Abstraction in Python

Python Iterators

Iterators in Python Yield Statement In Python

Python Generators

Python Generator

Python Decorators

Python Decorator

Python Functions and Methods

Python Built-in Functions Python String Methods Python List Methods Python Dictionary Methods Python Tuple Methods Python Set Methods

Python Modules

Python Modules Python Datetime Module Python Math Module Python Import Module Python Time Module Python Random Module Python Calendar Module CSV Module in Python Python Subprocess Module Python Subprocess

Python MySQL

Python MySQL Python MySQL Client Update Operation Delete Operation Database Connection Creating new Database using Python MySQL Creating Tables Performing Transactions

Python MongoDB

Python MongoDB

Python SQLite

Python SQLite

Python Data Structure Implementation

Python Stack Python Queue Python Linked List Python Hash Table Python Graph

Python Advance Topics

Speech Recognition in Python Face Recognition in Python Python Linear regression Python Rest API Python Command Line Arguments Python JSON Python Virtual Environment Type Casting in Python Python Collections Python Commands Python Data Visualization Python Debugger Python DefaultDict Python Enumerate

Python 3

Anaconda in Python 3 Anaconda python 3 installation for windows 10 List Comprehension in Python3

Misc

Python PPTX Python Pickle Python Seaborn Python Coroutine Python EOL Python Infinity Python math.cos and math.acos function Python Project Ideas Based On Django Reverse a String in Python Reverse a Number in Python Python Word Tokenizer Python Trigonometric Functions Python try catch exception GUI Calculator in Python Implementing geometric shapes into the game in python Installing Packages in Python Python Try Except Python Sending Email Socket Programming in Python Python CGI Programming Python Data Structures Python abstract class Python Compiler Python K-Means Clustering NSE Tools In Python Operator Module In Python Palindrome In Python Permutations in Python Pillow Python introduction and setup Python Functionalities of Pillow Module Python Argmin Python whois Python JSON Schema Python lock Return Statement In Python Reverse a sentence In Python tell() function in Python Why learn Python? Write Dictionary to CSV in Python Write a String in Python Binary Search Visualization using Pygame in Python Latest Project Ideas using Python 2022 Closest Pair of Points in Python ComboBox in Python Python vs R Best resources to learn Numpy and Pandas in python Check Letter in a String Python Python Console Python Control Statements Convert Float to Int in Python using Pandas Difference between python list and tuple Importing Numpy in Pycharm Python Key Error Python NewLine Python tokens and character set Python Strong Number any() Keyword in python Best Database in Python Check whether dir is empty or not in python Comments in the Python Programming Language Convert int to Float in Python using Pandas Decision Tree Classification in Python End Parameter in python __GETITEM__ and __SETITEM__ in Python Python Namespace Python GUI Programming List Assignment Index out of Range in Python List Iteration in Python List Index out of Range Python for Loop List Subtract in Python Python Empty Tuple Python Escape Characters Sentence to python vector Slicing of a String in Python Executing Shell Commands in Python Genetic Algorithm in python Get index of element in array in python Looping through Data Frame in Python Syntax of Map function in Python After Python What Should I Learn Python AIOHTTP Alexa Python Artificial intelligence mini projects ideas in python Artificial intelligence mini projects with source code in Python Find whether the given stringnumber is palindrome or not First Unique Character in a String Python Python Network Programming Python Interface Python Multithreading Python Interpreter Data Distribution in python Flutter with tensor flow in python Front end in python Iterate a Dictionary in Python Iterate a Dictionary in Python – Part 2 Allocate a minimum number of pages in python Assertion Errors and Attribute Errors in Python Checking whether a String Contains a Set of Characters in python Python Control Flow Statements *Args and **Kwargs in Python Bar Plot in Python Conditional Expressions in Python Function annotations() in Python How to Write a Configuration file in Python Image to Text in python import() Function in Python Import py file in Python Multiple Linear Regression using Python Nested Tuple in Python Python String Negative Indexing Reading a File Line by Line in Python Python Comment Block Base Case in Recursive function python ER diagram of the Bank Management System in python Image to NumPy Arrays in Python NOT IN operator in Python One Liner If-Else Statements in Python Sklearn in Python Python Ternary Operators Self in Python Python vs Java Python Modulo Python Packages Python Syntax Python Uses Python Bitwise Operators Python Identifiers Python Matrix Multiplication Python AND Operator Python Logical Operators Python Multiprocessing Python Unit Testing __init__ in Python Advantages of Python Is Python Case-sensitive when Dealing with Identifiers Python Boolean Python Call Function Python History Python Image Processing Python main() function Python Permutations and Combinations Difference between Input() and raw_input() functions in Python Conditional Statements in python Confusion Matrix Visualization Python Python Algorithms Python Modules List Difference between Python 2 and Python 3 Is Python Case Sensitive Method Overloading in Python Python Arithmetic Operators Assignment Operators in Python Is Python Object Oriented Programming language Division in Python Python exit commands Continue And Pass Statements In Python Colors In Python Convert String Into Int In Python Convert String To Binary In Python Convert Uppercase To Lowercase In Python Convert XML To JSON In Python Converting Set To List In Python Covariance In Python CSV Module In Python Decision Tree In Python Difference Between Yield And Return In Python Dynamic Typing In Python

How to

How to Substring a String in Python How to Iterate through a Dictionary in Python How to convert integer to float in Python How to reverse a string in Python How to take input in Python How to install Python in Windows How to install Python in Ubuntu How to install PIP in Python How to call a function in Python How to download Python How to comment multiple lines in Python How to create a file in Python How to create a list in Python How to declare array in Python How to clear screen in Python How to convert string to list in Python How to take multiple inputs in Python How to write a program in Python How to compare two strings in Python How to create a dictionary in Python How to create an array in Python How to update Python How to compare two lists in Python How to concatenate two strings in Python How to print pattern in Python How to check data type in python How to slice a list in python How to implement classifiers in Python How To Print Colored Text in Python How to develop a game in python How to print in same line in python How to create a class in python How to find square root in python How to import numy in python How to import pandas in python How to uninstall python How to upgrade PIP in python How to append a string in python How to open a file in python How to Open a file in python with Path How to run a Python file in CMD How to change the names of Columns in Python How to Concat two Dataframes in Python How to Iterate a List in Python How to learn python Online How to Make an App with Python

Sorting

Python Sort List Sort Dictionary in Python Python sort() function Python Bubble Sort

Programs

Factorial Program in Python Prime Number Program in Python Fibonacci Series Program in Python Leap Year Program in Python Palindrome Program in Python Check Palindrome In Python Calculator Program in Python Armstrong Number Program in Python Python Program to add two numbers Anagram Program in Python Even Odd Program in Python GCD Program in Python Python Exit Program Python Program to check Leap Year Operator Overloading in Python Pointers in Python Python Not Equal Operator Raise Exception in Python Salary of Python Developers in India What is a Script in Python

Python Packages

A package is a collection of Python modules that share a similar namespace and are generated by putting all of the modules in a single directory with certain special files like _init .py.

For a folder containing several modules like.py files to be recognized as a package in a directory structure, a special file called _init .py must also be stored in the folder, even if the file _init .py is empty. A library, on the other hand, can contain one or more packages and sub-packages.

Structure of a Package

Because python packages are simply collections of modules with a common namespace, this namespace is formed by creating a directory that contains all relevant modules. One of the things one should keep in mind is that - Packages are all directories that include multiple.py modules. A _init .py file, even if empty, must be present in a folder containing Python files for the folder to be recognized as a package.

Here is a figure explaining the same;

Python Packages

A folder's _init .py file shows that it is an importable Python package; otherwise, a folder is not regarded as a Python Package.

Procedure for Creating Packages

To create a package, you must follow a certain procedure, as discussed below.

1.    Make a Decision Regarding the Package's Basic Structure

It means you should know what your package's name will be (i.e., a directory/folder with that name will be created) and what modules and subfolders (to act as sub-packages) will be included.

For instance, let’s create a package named asPackageNewwith structure as shown below;

Python Packages

2.    Create a Directory Structure with Folders Labelled with Package and Subpackage Names.

As shown in the preceding example, we established a folder called PackageNew. We construct files/modules, i.e..py, files and subfolders with their own.py files inside this folder.

3.    In the Package and SubpackageFolders, Create _init .pyFiles.

Remember that Python will not check for submodules inside that directory if the _init .py file is missing; thus, efforts to import the module will fail.

4.    Connect it to Your Python Installation.

Once your package directory is ready, you can associate it with Python by adding it to the current Python distribution's site-packages folder.

In Python, you can only import a library and package if it is tied to its site-packages folder.

  • To check the path of the python site-packages folder, type the following two commands one after the other on the python prompt and try to locate the path of the site-packages folder:

    import sys
    print(sys.path)


    PYTHONPATH determines the directories that the Python interpreter will look at when importing modules, and the sys.path attribute provides vital information about PYTHONPATH.
  • Once you've determined the location of the site-packages folder, the simplest method is to copy your own package folder and paste it there. (But one should remember that this method is not considered the usual practice.)

    We simply opened the site-packages folder on our Windows installation and pasted the entire PackageNew folder.

5. Your package folder has now become a python library, allowing you to import its modules and utilize its functions after moving it into the site-packages folder of your current Python installation.

Note: The site-packages directory is the default target directory for all installed Python packages.

  • The Python interpreter recognizes the folder as a package using __init.py. It also defines which modules should have their resources imported.

Installing a Python Package

There are some packages that are in the standard library; the Python Package Index, sometimes known as PyPI, is the official repository for locating and downloading third-party packages. To install packages from PyPI, use the pip package installer:

$ pip install <name of the package>

Pip is a Python package manager that can install Python packages from various sources, including PyPI.

The conda command can be used to install Python packages if you installed Python with Anaconda or MinicondaTo install a Python package or module, type the following code in Anaconda Prompt.

$ conda install <name of the module>

Conda is simple to use, but it lacks the versatility of pip. If conda fails to install a package, you can always use pip.

Importing Modules

The import Statement:

The import statement makes the contents of the module available to the caller. As shown below, the import statement can be written in many forms.

The simplest form:

import<module_name>

A single import statement can contain many comma-separated modules:

import<module_name>[,<module_name>...]

Example:

Let's pretend we haven't installed any packages yet, do not worry cause Python comes with a vast library of pre-installed packages named the Python Standard Library. It contains capabilities for various tasks, including text processing and math. Let's have a look at the second option:

import math

  • It should be noted that this does not give the caller immediate access to the module's contents. Each module has its own private symbol table, which serves as the global symbol table for all objects in the module. As previously stated, a module defines its own namespace.
  • The import <modulename> statement merely adds <modulename> to the caller's symbol table. The private symbol table of the module stores the objects declared in the module.
  • Objects in the module are only accessible from the caller when prefixed with <module name> via dot notation.

Assume you've generated a file called module1.py that contains the following code:

array1 = [150, 250,350, 450]
string1 = "Python packages are fun to read and experiment with."


def function1(argument):
    print(f'argument = {argument}')


class cls1:
    pass

In module1.py, several objects are defined like:

  • array1 à that is an array.
  • function1() à that is a function.
  • cls1 à that is a class.
  • string1 à that is a string.

Here in the code below, after the following import statement, module1 is placed into the local symbol table. Thus, module1 has meaning in the caller’s local context:

>>>importmodule1
>>>module1
<module 'module1' from 'C:\\Users\\kitty\\Documents\\Python\\doc\\module1.py'>


String1 and function1, on the other hand, are stored in the module's private symbol table and have no local value.


>>>string1
Python Packages

>>>function1('python')

Python Packages

As you can see, therefore, the names of objects declared in the module must be prefixed by module1 to be accessed in the local context, as shown below;

>>>module1.string1

‘Python packages are fun to read and experiment with.’

>>>module1.function1('python')
argument = python

from <module_name> import <name(s)>

Individual objects from the module can be imported directly into the caller's symbol table using a different form of the import statement:

from <module_name> import <name(s)>

Following the execution of the above statement, the caller's environment can refer to <name(s)> without the <module name> prefix.

For example: if you want to use only the log function from the math module, then you can code as given below,

>>> from math import log

from <module_name> import <name> as <alternate_name>

Individual objects can also be imported, but they must be entered into the local symbol table with alternate names.

from <module_name> import <name> as <alternate_name>[, <name> as <alternate_name> …]

This allows names to be entered directly into the local symbol table but tries to avoid conflicts with previously used names.

Example:

>>>from math import fabs as fs
>>>math.fs(x)

import <module_name> as <alternate_name>

You can also import a module as a whole under a different name.

import <module_name> as <alternate_name>

Example:

	>>>import math as mh
>>>mh.fabs(x)

Note: Another way is to import all of the resources from a module into your namespace:

>>> from math import *

Module Reloading

If you alter a module's script while programming in interactive mode, the modifications will not be imported, even if you issue another import statement. In this situation, you'll want to utilize the importlib library's reload() function:

>>>import importlib
>>>importlib.reload(<some module name>)

Using the dir() Function

The dir() method returns a list of the function names (or variable names) in a module.

All modules, even those you write yourself, can use the dir() function.

Example:

import math
x = dir(math)
print(x)

Output:

Python Packages
Python Packages
Python Packages
Python Packages
Python Packages
Python Packages
Python Packages
Python Packages



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