Python Modules: Enhancing Code Capabilities

Modules Python allows for the inclusion of code packages called modules to support additional capabilities. Packages fall into two broad categories: Standard (built-in) Third party Professor John Carelli, Kutztown University

Useful Standard Libraries The following modules are included in the standard Python distribution os and sys: tools for interfacing with the operating system. math: mathematical functions and operations itertools: tools for constructing and interacting with iterators and generators. random: tools for generating pseudorandom numbers json and csv: tools for reading standard formats pickle: save and load objects to/from disks Professor John Carelli, Kutztown University

Importing Modules In order to use a module (regardless of the source), it must be loaded using the import statement Various ways: import module import module as mod from module import func1, func2, from module import * Professor John Carelli, Kutztown University

Explicit import # explicit import import math # explicit import using an alias import random as rand # module contents accessed using # name/alias with dot operator num= rand.random() root= math.sqrt(num) Professor John Carelli, Kutztown University

Import of contents # explicit import of specific content from math import sqrt # implicit import of all contents from random import * # no need to use module name num= random() root= sqrt(num) Caution when using implicit import! May get naming conflicts of contents between modules or scripted code! (usually better to just import what you need) Professor John Carelli, Kutztown University

Third-party Modules The following are some commonly used third-party* modules available in Python numpy: efficient storage and manipulation of multi- dimensional dense arrays. pandas: provides a labeled interface to multi- dimensional data. matplotlib: data visualizations (plotting) * In general, third-party modules must be downloaded and installed separately (although these are included in an Anaconda installation) Professor John Carelli, Kutztown University

Python Scripts as Modules Any Python script can be treated as a module It can be imported into another script Statements in the script will run Functions/objects defined in the script are accessible to the importing script Professor John Carelli, Kutztown University

Module Convention It is possible to import the contents of a script without executing code that would normally run if the script were executed as a Python program if __name__ == '__main__': # Statements in this block will only be executed # when the script is run as a stand-alone program # They will not be executed when imported! milesModule.py Professor John Carelli, Kutztown University