Libraries#
A piece of code that someone else wrote that you can use in your code.
Modules#
Is a library that has one or more functions built into it.
Re-usability code.
random#
random is a built-in module in Python. It has a set of functions to generate random numbers.
import#
To use a module, you have to import it.
import random
coin = random.choice(["head", "tails"])
print(coin)
from#
Is the keyword to import a specific function from a module.
from random import choice
coin = choice(["head", "tails"])
print(coin)
randint, shuffle#
randint#
import random
number = random.randint(1, 10)
print(number)
shuffle#
import random
cards = ["jack", "queen", "king"]
random.shuffle(cards)
for card in cards:
print(card)
statistics#
statistics is a built-in module in Python. It has a set of functions to calculate statistics.
import statistics
print(statistics.mean([100, 90]))
Command-line Arguments, sys#
sys module, provides access to some variables used or maintained by the interpreter and to functions that interact strongly with the interpreter.
- sys.argv: argument vector, a list of strings representing the arguments.
import sys
if len(sys.argv) < 2:
print("Too few arguments")
elif len(sys.argv) > 2:
print("Too many arguments")
else:
print("hello, my name is", sys.argv[1])
sys.exit#
Exit from Python.
import sys
if len(sys.argv) < 2:
sys.exit("Too few arguments")
elif len(sys.argv) > 2:
print("Too many arguments")
print("hello, my name is", sys.argv[1])
slices#
A slice is a portion of a list.
import sys
if len(sys.argv) < 2:
sys.exit("Too few arguments")
for arg in sys.argv[1:]:
print("hello, my name is", arg)
Packages, PyPI, pip#
- Package: is a collection of modules.
- PyPI: Python Package Index, is a repository of software for the Python programming language.
- pip: is a package installer for Python.
cowsay#
Install#
pip install cowsay
Usage#
import cowsay
import sys
if len(sys.arg) == 2:
cowsay.cow("hello, " + sys.argv[1])
APIs, requests, JSON#
- API: Application Programming Interface.
- requests: is a simple HTTP library for Python.
- JSON: JavaScript Object Notation, a language-independent data format.
Pretty print JSON#
import json
import requests
import sys
if len(sys.argv) != 2:
sys.exit()
response = requests.get("https://itunes.apple.com/search?entity=song&limit=1&term=" + sys.argv[1])
print(json.dumps(response.json(), indent=2))
Printing the track name from the API#
import json
import requests
import sys
if len(sys.argv) != 2:
sys.exit()
response = requests.get("https://itunes.apple.com/search?entity=song&limit=50&term=" + sys.argv[1])
o = response.json()
for result in o["results"]:
print(result["trackName"])
Custom Libraries#
Create your own library.
sayings.py#
def main():
hello("world")
goodbye("world")
def hello(name):
print(f"hello, {name}")
def goodbye(name):
print(f"goodbye, {name}")
if __name__ == "__main__":
main()
say.py#
import sys
from sayings import hello
if len(sys.argv) == 2:
hello(sys.argv[1])
