Python. libraries. modules. and. all.pdf
- 1. Computer Science Class XII Python Libraries
- 2. 1. Python Standard Library: math module: for mathematical functions cmath module:- mathematical functions for complex numbers. random module :- functions for generating pseudo- random numbers. string module: for string/text-related functions. USING PYTHON STANDARD LIBRARYāS FUNCTIONS AND MODULES Pythonās standard library is very extensive, offering a wide range of modules and functions. The library contains built-in modules (written in C) that provide access to system functionality such as ļ¬le I/O, that would otherwise be inaccessible to Python programmers, as well as modules written in Python that provide standardized solutions for many problems that occur in everyday programming. Some of these important modules are explicitly designed to encourage and enhance the portability of Python programs.
- 3. 2. NumPy Library- NumPy is the fundamental package for scientiļ¬c computing and manipulate numeric array with Python. 3. SciPy Library(pronounced āSigh Pieā) is a Python-based ecosystem of open-source software for mathematics, science, and engineering. 4. Tkinter Library :Tkinter is actually an inbuilt Python module used to create simple GUI apps. It is the most commonly used module for GUI apps in the Python. 5. Matplotlib Library: Matplotlib is one of the most popular Python packages used for data visualization. It is a cross-platform library for making 2D plots from data in arrays.
- 4. Processing of import <module> command 1.Imported moduleās code gets executed after interpretation. 2.All the programs and variables of imported module are present in the program. Python import statement import math print(ā2 to the power 3 is ", math.pow(2,3)) Import with renaming import math as mt print(ā2 to the power 3 is ", mt.pow(2,3)) Processing of from <module> import <object> command 1.Imported moduleās code gets executed after interpretation. 2.Only asked programs and variables of imported module are present in the program. Python from...import statement from math import pow print(ā2 to the power 3 is ", pow(2,3)) Import all names from math import * print(ā2 to the power 3 is ", pow(2,3))
- 5. Python - Math Module We have already discussed major functions using math module. Python provides many other mathematical built-in functions as well. These include trigonometric functions, representation functions, logarithmic functions, angle conversion functions, etc. In addition, two mathematical constants are also deļ¬ned in this module. Pie (Ļ) is a well-known mathematical constant, which is deļ¬ned as the ratio of the circumference to the diameter of a circle and its value is 3.141592653589793. import math math.pi 3.141592653589793 from math import pi print(pi) 3.141592653589793 or Another well-known mathematical constant deļ¬ned in the math module is e. It is called Euler's number and it is a base of the natural logarithm. Its value is 2.718281828459045. math.e 2.718281828459045
- 6. The math module presents two angle conversion functions: degrees() and radians() , to convert the angle from degrees to radians and vice versa. For example, the following statements convert the angle of 30 degrees to radians and back. math.radians(30) 0.5235987755982988 math.degrees(math.pi/6) 29.999999999999996 math.log() The math.log() method returns the natural logarithm of a given number. The natural logarithm is calculated to the base e. math.log(10) 2.302585092994046
- 7. Python - Random Module Functions in the random module depend on a pseudo-random number generator function random(), which generates a random ļ¬oat number between 0.0 and 1.0. random.random(): Generates a random ļ¬oat number between 0.0 to 1.0. The function doesn't need any arguments. import random print(random.random()) random.randint(): Returns a random integer between the speciļ¬ed integers. import random print(random.randint(3, 9)) randrange() Method import random print(random.randrange(3, 90,2))
- 8. String Methods Python has a set of built-in methods that you can use on strings. Method Description capitalize() Converts the ļ¬rst character to upper case count() Returns the number of times a speciļ¬ed value occurs in a string ļ¬nd() Searches the string for a speciļ¬ed value and returns the position of where it was found index() Searches the string for a speciļ¬ed value and returns the position of where it was found isalnum() Returns True if all characters in the string are alphanumeric isalpha() Returns True if all characters in the string are in the alphabet isdecimal() Returns True if all characters in the string are decimals isdigit() Returns True if all characters in the string are digits islower() Returns True if all characters in the string are lower case isnumeric() Returns True if all characters in the string are numeric isupper() Returns True if all characters in the string are upper case lower() Converts a string into lower case replace() Returns a string where a speciļ¬ed value is replaced with a speciļ¬ed value split() Splits the string at the speciļ¬ed separator, and returns a list
- 9. Relation Between Python Libraries, Module and Package ā¢A module is a ļ¬le containing python deļ¬nition, functions, variables, classes and statements. The extension of this ļ¬le is ā.pyā. ā¢While Python package, is directory (folder) of python modules. ā¢A library is collection of many packages in python. Generally there is no difference between python package and python library.
- 10. Module in Python ā¢A module is a ļ¬le containing python deļ¬nition, functions, variables, classes and statements. The extension of this ļ¬le is ā.pyā. Advantagesā āIts biggest advantage is that we can import its functionality in any program and use it. āReusability is one of the biggest advantages. āIt helps in logically organization of Python code. āProgramming becomes very easy when we use the collection of same types of codes. āCategorization : same attributes can be stored in one module.
- 13. Namespaces in Python ā¢We imported a module in to a program which was referred as a namespace. ā¢To deļ¬ne a Namespace it is necessary to deļ¬ne its name. ā¢Python name is a kind of identiļ¬er which we use to access any python object. And in Python each and everything is an object. ā¢Namespaces is used to separate the different sections of a program. ā¢Python has 3 types of namespaces - āGlobal āLocal āBuilt-in Each module creates its own global namespace. When we call a function then a local python namespace is created where all the names of functions are exist.
- 16. PACKAGE / LIBRARY ā¢Python Package is the collection of same type of modules. ā¢You can use built in package as well as your own package. ā¢Python Package is a simple directory. Modules are stored in that directory. ā¢Package or library are generally same. ā¢Steps to make a package is as follows ā (geometry) 1.We create a folder (directory) named geometry which will contain two ļ¬les area.py and volume.py 2.In the same directory we will put another ļ¬le named ā__init__.pyā 3.__init__.py is necessary because this is the ļ¬le which tells Python that directory is package. And this ļ¬le initializes the package 4.Then we import the package and use the content.
- 18. Standard Python Libraries We have already discussed about math and string module. Same way we will discuss two more important libraries. - datetime library or datetime module. Python supports yyyy-mm-dd format for date. It has tow important classes - ādate class today ( ) year( ) month ( ) day ( ) ātime class now ( ) hour ( ) minute ( ) second ( )