python快速入门【三】-----For 循环、While 循环

#取第一个列表成员（可迭代），暂称它数字（打印它）
#取列表的第二个成员（可迭代），暂时将其称为数字，等等......

for number in [23, 41, 12, 16, 7]: 
    print(number)
print('Hi')

23
41
12
16
7
Hi

friends = ['steve', 'rachel', 'michael', 'adam', 'monica']
for index, friend in enumerate(friends):
    print(index,friend)

0 steve
1 rachel
2 michael
3 adam
4 monica

text = '''On a dark desert highway, cool wind in my hair Warm smell of colitas, rising up through the air Up ahead in the distance, I saw a shimmering light My head grew heavy and my sight grew dim I had to stop for the night There she stood in the doorway; I heard the mission bell And I was thinking to myself, "This could be Heaven or this could be Hell" Then she lit up a candle and she showed me the way'''

print(text)

On a dark desert highway, cool wind in my hair Warm smell of colitas, rising up through the air Up ahead in the distance, I saw a shimmering light My head grew heavy and my sight grew dim I had to stop for the night There she stood in the doorway; I heard the mission bell And I was thinking to myself, "This could be Heaven or this could be Hell" Then she lit up a candle and she showed me the way

for char in '-.,;\n"\'':
    text = text.replace(char,' ')
print(text)

On a dark desert highway  cool wind in my hair Warm smell of colitas  rising up through the air Up ahead in the distance  I saw a shimmering light My head grew heavy and my sight grew dim I had to stop for the night There she stood in the doorway  I heard the mission bell And I was thinking to myself   This could be Heaven or this could be Hell  Then she lit up a candle and she showed me the way

# Split converts string to list.
# Each item in list is split on spaces
text.split(' ')[0:20]

['On',
 'a',
 'dark',
 'desert',
 'highway',
 '',
 'cool',
 'wind',
 'in',
 'my',
 'hair',
 'Warm',
 'smell',
 'of',
 'colitas',
 '',
 'rising',
 'up',
 'through',
 'the']

# Dont want to have non words in my list for example ''
# which in this case are things of zero length
len('')

0

# Making new list with no empty words in it
cleaned_list = []

for word in text.split(' '): 
    word_length = len(word)
    if word_length > 0:
        cleaned_list.append(word)

cleaned_list[0:20]

['On',
 'a',
 'dark',
 'desert',
 'highway',
 'cool',
 'wind',
 'in',
 'my',
 'hair',
 'Warm',
 'smell',
 'of',
 'colitas',
 'rising',
 'up',
 'through',
 'the',
 'air',
 'Up']

cleaned_list = []

for word in text.split(' '): 
    if word == '':
        continue
    cleaned_list.append(word)
cleaned_list[1:20]

['a',
 'dark',
 'desert',
 'highway',
 'cool',
 'wind',
 'in',
 'my',
 'hair',
 'Warm',
 'smell',
 'of',
 'colitas',
 'rising',
 'up',
 'through',
 'the',
 'air',
 'Up']

cleaned_list = []

for word in text.split(' '): 
    if word == 'desert':
        print('I found the word I was looking for')
        break
    cleaned_list.append(word)
cleaned_list

I found the word I was looking for

['On', 'a', 'dark']

# Making empty lists to append even and odd numbers to. 
even_numbers = []
odd_numbers = []

for number in range(1,51):
    if number % 2 == 0:
        even_numbers.append(number)
    else: 
        odd_numbers.append(number)    

print("Even Numbers: ", even_numbers)

Even Numbers:  [2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50]

print("Odd Numbers: ", odd_numbers)

Odd Numbers:  [1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49]

# Everytime through the loop, it checks condition everytime until count is 6 
# can also use a break to break out of while loop. 
count = 0
while count <= 5:
    print(count)
    count = count + 1

0
1
2
3
4
5

count = 0
while count <= 5:
    if count == 2:
        break
    count += 1
    print (count)

1
2

num = 0
while True:
    if num == 2:
        print('Found 2')
        break
    num += 1
    print (num)

1
2
Found 2

# 1 divided by 5 is 0 remainder 1
1 % 5

1

# 5 divided by 5 is 0 remainder 0
5 % 5

0

x = 1
while x % 5 != 0:
    x += 1
    print(x)

2
3
4
5

candidates = list(range(0, 5))
candidates

[0, 1, 2, 3, 4]

while len(candidates) > 0: 
    first = candidates[0]
    candidates.remove(first)
    print(candidates)

[1, 2, 3, 4]
[2, 3, 4]
[3, 4]
[4]
[]