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8.1 Libraries

Libraries

Libraries are collections of methods that you can use when you're programming. Libraries are Python code that serves a certain function. For example, let's say you want a random number generator. You import the random module, and then you can use it to get random numbers by calling methods from it:

  • First, import the random module: import random
  • Then, call a method from the random module: random.randrange(1, 10)
  • This gives us a random number between 1 and 10 (exclusive), as those are the arguments we passed in
# import the random module
import random

# returns a random number between 1 and 10 (exclusive)
number = random.randrange(1, 10)
print(number)

View code on GitHub.

💡

random.randint(a, b) is the same as random.randrange(a, b), except that b is inclusive for randint

Different Ways to Import

# import the entire module
import module_name

# import the module and refer to it as a different name
# in your code
# (typically, it's a shortened name)
# this is called aliasing a module
import module_name as shortened_name

# from a certain module, import only a certain class,
# variable, or method
from module_name import thing_in_module

# wildcard (*) import - imports everything in that module
from module_name import *
💡

if you use from _ import _, you don't need to do module_name.method() every time you call a method. However, you must do module_name.method() for the 1st and 2nd way of importing shown above

View code on GitHub.

Practice

Guess

Import the random module. Store a random secret number in a variable called secret_number (use randrange or randint). The secret number should be from 1 to 20 (inclusive). Ask the user to keep guessing the number until they get it right. You might want to print messages to tell the user if they guessed right or wrong

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