Loops

Basic

primes = [2, 3, 5, 7]
for prime in primes:
    print(prime)

Prints: 2 3 5 7

With index

animals = ["dog", "cat", "mouse"]
# enumerate() adds counter to an iterable
for i, value in enumerate(animals):
    print(i, value)

Prints: 0 dog 1 cat 2 mouse

While

x = 0
while x < 4:
    print(x)
    x += 1  # Shorthand for x = x + 1

Prints: 0 1 2 3

Break

x = 0
for index in range(10):
    x = index * 10
    if index == 5:
     break
    print(x)

Prints: 0 10 20 30 40

Continue

for index in range(3, 8):
    x = index * 10
    if index == 5:
     continue
    print(x)

Prints: 30 40 60 70

Range

for i in range(4):
    print(i) # Prints: 0 1 2 3

for i in range(4, 8):
    print(i) # Prints: 4 5 6 7

for i in range(4, 10, 2):
    print(i) # Prints: 4 6 8

With zip()

words = ['Mon', 'Tue', 'Wed']
nums = [1, 2, 3]
# Use zip to pack into a tuple list
for w, n in zip(words, nums):
    print('%d:%s, ' %(n, w))

Prints: 1:Mon, 2:Tue, 3:Wed,

for/else

nums = [60, 70, 30, 110, 90]
for n in nums:
    if n > 100:
        print("%d is bigger than 100" %n)
        break
else:
    print("Not found!")

Also see: Python Tips

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