Modules & Packages

Syntax

<pre><code># Importing built-in modules
import math
print(math.sqrt(16))   # 4.0
print(math.pi)         # 3.14159...

import random
print(random.randint(1, 10))  # Random int
print(random.choice(["a", "b", "c"]))

import datetime
now = datetime.datetime.now()
print(now.strftime("%Y-%m-%d %H:%M:%S"))

# From import (import specific names)
from math import sqrt, pi
print(sqrt(25))  # 5.0 (no math. prefix)

# Import with alias
import numpy as np  # convention
import pandas as pd

# Creating your own module (save as mymath.py)
# def add(a, b): return a + b
# def multiply(a, b): return a * b

# Then import it:
# import mymath
# print(mymath.add(3, 4))

# Useful built-in modules
# os — operating system interface
# sys — system-specific parameters
# json — JSON encode/decode
# csv — CSV files
# re — regular expressions
# time — time-related functions
</code></pre>