4.5 순회 하기

20 Feb 2018 • IntroducingPython 
rabbits = ['Flopsy', 'Mopsy', 'Cottontail', 'Peter']
current = 0
while current < len(rabbits):
print(rabbits[current])
current += 1

Flopsy Mopsy Cottontail Peter

for rabbit in rabbits:
print(rabbit)

Flopsy Mopsy Cottontail Peter

word = 'cat'
for letter in word:
print(letter)

c a t

accusation = {'room': 'ballroom', 'weapon': 'lead pipe', 'person': 'Col. Mustard'}
for card in accusation:
print(card)

room weapon person

for value in accusation.values():
print(value)

ballroom lead pipe Col. Mustard

for item in accusation.items():
print(item)

(‘room’, ‘ballroom’) (‘weapon’, ‘lead pipe’) (‘person’, ‘Col. Mustard’)

for card, contents in accusation.items():
print('Card', card, 'has the contents', contents)

Card room has the contents ballroom Card weapon has the contents lead pipe Card person has the contents Col. Mustard

4.5.3 break확인 하기: else

cheeses = []
for cheese in cheeses:
print('This shop has some lovely', cheese)
break
else:
print('This is not much of a cheese shop, is it?')

This is not much of a cheese shop, is it?

while문과 마찬가지인 for문의 else도 뭔가 좀 이상한데, for문을 뭔가 찾는 것으로 생각하고 찾지 못했을 경우 else를 호출 된다고 생각하면 쉽다.

cheeses = []
found_one = False
for cheese in cheeses:
found_one = True
print('This shop has some lovely', cheese)
break
if not found_one:
print('This is not much of a cheese shop, is it?')

This is not much of a cheese shop, is it?

4.5.4 여러 시퀀스 순회하기: zip()

** zip() 함수를 사용해서 여러 시퀀스를 병렬로 순회할 수 있다. **

days = ['Monday', 'Tuesday', 'Wednesday']
fruits = ['banana', 'ornage', 'peach']
drinks = ['coffee', 'tea', 'beer']
desserts = ['tiramisu', 'ice cream', 'pie', 'pudding']
for day, fruit, drink, dessert in zip(days, fruits, drinks, desserts):
print(day, ": drink", drink, "- eat", fruit,"- enjoy", dessert)

Monday : drink coffee - eat banana - enjoy tiramisu

Tuesday : drink tea - eat ornage - enjoy ice cream

Wednesday : drink beer - eat peach - enjoy pie

여러 시퀀스중 가장 짧은 시퀀스가 완료되면 zip()은 멈춘다 pudding을 얻을수 없다.

english  = 'Monday', 'Tuesday', 'Wendesday'
french = 'Lundi', 'Mardi', 'Mercredi', 'asdasd'

list(zip(english, french))

[(‘Monday’, ‘Lundi’), (‘Tuesday’, ‘Mardi’), (‘Wendesday’, ‘Mercredi’)] 두개의 튜플을 만들기 위해 zip()을 사용한다 zip()에 의해 반환되는 값은 튜플이나 리스트 자신이 아니라 하나로 반환될 수 있는 순회 가능한 값이다. (asdasd는 없다)

dict(zip(english, french))

{‘Monday’: ‘Lundi’, ‘Tuesday’: ‘Mardi’, ‘Wendesday’: ‘Mercredi’}

4.5.5 숫자 시퀀스 생성하기: range()

** range(start, stop, step) ** zip() 와 같이 순회가능한 객체를 반환 그래서 반복문으로 순회 가능

for x in range(0, 3):
print(x)

0 1 2

list(range(0,3))

[0, 1, 2]

for x in range(2, -1, -1):
print(x)

2 1 0

list(range(2, -1, -1))

[2, 1, 0]

list(range(0, 11, 2))

[0, 2, 4, 6, 8, 10]

 IntroducingPython

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