Quick Python 3 — Code Section Inventory

my_list[5] = my_list[4] + my_list[3]

x = 1

if n == 1:
    print("One")
elif n == 2:
    print("Two")
elif n == 3:
    print("Three")
else:
    print("Many")
    print("or maybe none at all")

n = 5
while n > 0:
    print(n)
    n -= 1
print("Blast off!")

n = 6
while (n := n - 1) > 0:
    print(n)
print("Blast off!")

for i in [5, 4, 3, 2, 1]:
    print(i)
print("Blast off!")

for i in range(5, 0, -1):
    print(i)
print("Blast off!")

from math import sqrt, log

from math import *

name = input("What is your name? ")
print("Hello,", name)

question = "How old are you, " + name + "? "
age = int(input(question))

def largest(a, b, c):
    """Return the largest of a, b, and c."""
    if a >= b and a >= c:
        return a
    elif b >= a and b >= c:
        return b
    return c

# Program to print prime numbers

def is_prime(n):
    """Test if a number n is prime."""
    divisor = 2
    while divisor * divisor <= n:
        if n % divisor == 0:
            return False
        divisor += 1
    return True

def print_primes(limit):
    for i in range(2, limit + 1):
        if is_prime(i):
            print(i, end=' ')

n = input("Print all primes up to: ")
print_primes(int(n))

x = [0] * 3
for i in range(0, 3):
    x[i] = [0] * 5

a, b, c = 1, 2, 3

a, b = b, a  # the values of a and b are interchanged

s = {10, "ten", "X"}

for elem in s:
    print(elem)

phones = {"Alice":5551212, "Jill":5556789, "Bob":5559999}

phones["Xavier"] = 5556666

del phones["Xavier"]

for e in my_list:
    print(e)

for i in range(0, len(my_list)):
    print(my_list[i], "is at", i)

for index, value in enumerate(my_list):
    print(value, "is at", index)

for e in my_set:
    print(e)

for k in my_dict:
    print(k)  # prints just the keys

for k in my_dict.keys():
    print(k)  # prints just the keys

for v in my_dict.values():
    print(v)  # prints just the values

for k in my_dict:
    print(k, "->", my_dict[k])

for t in my_dict.items():
    print(t)  # prints (key, value) tuples

for k, v in my_dict.items():
    print(k, "is", v)

try:
    # code that could go wrong
except SomeErrorType:
    # what to do if it goes wrong
finally:
    # what to do afterwards

number = None
while number is None:
    try:
        n = input("Enter an integer: ")
        number = int(n)
    except Exception:
        print("Try again!")
print("Your number is", number)

count = 0
with open(file_name, 'r') as f:
    while f.readline():
        count += 1

class Person(object):
    name = 'Joe'
    age = 23

    def say_hi(self):
        print('Hello, Joe.')

class Person(object):

    def __init__(self, name, age):
        self.name = name
        self.age = age


    def say_hi(self):
        print('Hello', self.name)

def get_older(self):
    self.age += 1

def get_much_older(self, years):
    for i in range(0, years):
        self.get_older()

class Friend(Person):
    def smile(self):
        print('¯\_(^-^)_/¯')

meg = Person('Margaret', 25)
bob = Friend('Robert', 33)

def say_hi(self, extra):
    print('Hi!', extra)

def say_hi(self, extra):
    super().say_hi()
    print(extra)

def __init__(self, name, age, nick):
    super().__init__(name, age)
    self.nickname = nick

<__main__.Friend object at 0x1064728d0>

def __str__(self):
    return self.name + "'s age is " + str(self.age)

Margaret's age is 19

a = 5  # bind a to 5
b = a  # copy a's binding into b
a = 6  # change the binding of a
print(b) # b is still bound to 5

a = [1, 2, 3]  # bind a to the list
b = a          # copy a's binding into b
a = [4, 5, 6]  # change the binding of a
print(b)  # b is still bound to [1, 2, 3]

a = [1, 2, 3]  # bind a to the list
b = a     # copy a's binding into b
a[0] = 99 # change the list, not the bindings
print(b)  # b still bound to the same list,
          #  but the list is now [99, 2, 3]

def foo(a, b):
    a[0] = 99
    b = [7, 8]

a = [1, 2, 3]
b = [1, 2, 3]
foo(a, b)
print(a, b) # [99, 2, 3] [1, 2, 3]

grades = [["Mary", "A+"], ["Don", "C-"]]
grades2 = grades[:]
grades2[0] = ["Bob", "B"]
grades2[1][1] = "F"
print(grades)  # [['Mary', 'A+'], ['Don', 'F']]
print(grades2) # [['Bob', 'B'], ['Don', 'F']]

import copy
grades3 = copy.deepcopy(grades)
grades3[1][1] = "D+"
# grades is unchanged

for _ in range(0, 3):
    print("Hello!")

def indent(line: str, amount: int) -> str:
    indented_line:str = ' ' * amount + line
    return indented_line

from typing import List, Set, Dict, Union, Optional

Number = Union[int, float]

f'{"abc":6}'  is  'abc   '
f'{"abc":>6}' is  '   abc'
f'{123:6d}'   is  '   123'
f'{123:<6d}'  is  '123   '
f'{pi:6.2f}'  is  '  3.14'
f'{pi:<6.2f}' is  '3.14  '

 print('pi is {:8.4f}'.format(pi))

class MyList():
    def __init__(self, ls):
        self.ls = ls

    def __iter__(self):
        return Reverser(self.ls)

class Reverser():
    def __init__(self, ls):
        self.ls = ls
        self.index = len(self.ls)

    def __next__(self):
        self.index = self.index - 1
        if self.index >= 0:
            return self.ls[self.index]
        raise StopIteration

ls = MyList([1, 2, 3, 4])
for e in ls:
    print(e)

ls = MyList([1, 2, 3, 4])
it = iter(ls)
while True:
    try:
        print(next(it))
    except StopIteration:
        break

word = 'generator'
gen = (c for c in word if c in 'aeiou')

for i in gen:
    print(i, end=' ')

def powers_of_two():
    n = 2
    for i in range(0, 5):
        yield n
        n *= 2

gen = powers_of_two()
for n in gen:
    print(n)

gen = powers_of_two()
while True:
    try:
        print(next(gen))
    except StopIteration:
        break

The call gen = powers_of_two() returns a generator and puts it in gen.
The first call of next(gen) executes the generator down to the yield statement, and returns the yielded value, just like a normal return statement. But in addition, the generator remembers where it left off.
A subsequent call to next(gen) will cause the generator to resume execution where it left off, that is, immediately after the yield statement. All the values of local variables will have been retained. As far as the generator is concerned, it is as if the yield had never happened. In this example, the for loop keeps running.

def foo(a, b, /, c, d, *, e, f):
    print(a, b, c, d, e, f)

def biggest(values):
    big = values[0]
    for v in values:
        if v > big:
            big = v
    return big

def most(values, more):
    best = values[0]
    for v in values:
        if more(v, best):
            best = v
    return best

def larger(a, b):
    return a > b

most([1, 6, 1, 8, 0], larger)

def longer(a, b):
    return len(a) > len(b)

most(["a", "generic", "list"], longer)

lambda a, b: len(a) > len(b)

print(most(["a", "generic", "list"],
      lambda a, b: len(a) > len(b)))

def get_digits(number):
    """Return a list of digits in an int or string."""
    string = str(number)
    return [x for x in string if x.isdigit()]

>>> get_digits("124c41")
['1', '2', '4', '4', '1']
>>> get_digits(1213141)
['1', '2', '1', '3', '1', '4', '1']

def get_digits(number):
    """Return a list of digits in an int or string."""
    >>> get_digits("124c41")
    ['1', '2', '4', '4', '1']
    >>> get_digits(1213141)
    ['1', '2', '1', '3', '1', '4', '1']
    """
    string = str(number)
    return [x for x in string if x.isdigit()]

import doctest
doctest.testmod()

def test_add(self):
    self.assertEqual(4, add(2, 2))
    self.assertEqual(0, add(2, -2))

self.assertRaises(ZeroDivisionError, 5/0)

if __name__ == '__main__':
    main()

unittest.main()

def get_digits(number):
    """Return a list of digits in an int or string."""
    string = str(number)
    return [x for x in string if x.isdigit()]

def main():
    s = input("Enter something: ")
    digits = get_digits(s)
    print("Digits found:", digits)
    if digits != []:
        main()

# Call main() if and only if started from this file
if __name__ == '__main__':
    main()

import unittest
from get_digits import *

class test_get_digits(unittest.TestCase):

    def test_get_digits(self):
        s = get_digits("<0.12-34 56abc789x")
        self.assertEqual(list("0123456789"),
                         get_digits(s))
        self.assertEqual(list("1230"),
                         get_digits(1230))

unittest.main()

import unittest
import testfoo, testbar

def suite():
    suite = unittest.TestSuite()
    suite.addTest(
      unittest.makeSuite(
        testfoo.TestFoo))
    suite.addTest(
      unittest.makeSuite(
        testbar.TestBar))
    return suite

if __name__ == '__main__':
    test_suite = suite()
    runner = unittest.TextTestRunner()
    runner.run (test_suite)

from tkinter import *
import tkinter.ttk

top = Tk()

top.mainloop()

import tkinter
root = tkinter.Tk()
root.withdraw()

from tkinter import *
import tkinter.ttk

from random import randint

def roll():
    n = str(randint(1, 6))
    result.configure(text=n)

top = Tk()

roll_button = Button(top, text='Roll', command=roll)
result = Label(top, width=12)

roll_button.grid(row=0)
result.grid(row=1)

from statistics import *
a = [1, 2, 3, 4, 5, 5, 78]
print(f"{mean(a)=}, {median(a)=}, {mode(a)=}")

print(f"{stdev(a):6.2f}, {variance(a):6.2f}")