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Modules and import

A module is a file of ready-made functions you can use in your own program. The standard library has many, such as math, random and csv. You can also make your own modules by putting functions in a separate file and importing it.

\texttt{import math}

import the whole module, use math.sqrt

\texttt{from math import sqrt, pi}

import specific names

\texttt{import numpy as np}

import with a shorter name

Symbols

$\texttt{math}$	mathematical functions
$\texttt{random}$	random numbers
$\texttt{csv}$	read and write table files

Example

The hypotenuse of a triangle with legs 3 and 4:

$\texttt{math.hypot(3, 4)}$ gives 5.0.

Avoid from module import *. Then you no longer know where names come from.

Practise files, errors and modules for free →

← Error handling

Part of Programming with Python: Files, errors and modules.