[Python] study notes 5-For loop

For loop

It is a common method for iterating the elements of
an object. Any object with an iterable method can be used in a for loop.
A unique feature of python is that the code block is not surrounded by {} or begin, end.
In contrast, Python uses indentation, and the lines within the block must be indented by tabs, or 4 spaces relative to the surrounding commands.

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

Results:
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1. Enumeration The
enumeration function returns a tuple containing the count of each iteration (starting from the default of 0) and the value obtained by the iteration sequence

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

Result:
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Practice a question:

#将这段话的标点符号去掉，并且把它分开到列表中
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 a in ['-',',',';','\"']:
    text=text.replace(a,' ')#用空格代替

print(text)

text=text.split(' ')[0:100]#用空格给分开
print(text)

Result:
Insert picture description here
2. len('')

#将这段话的标点符号去掉，并且把它分开到列表中
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 a in ['-',',',';','\"']:
    text=text.replace(a,' ')#用空格代替

list=[]
for a in text.split(' '):
    if len(a)>0:#如果提取出来的长度大于0就放进列表中
        list.append(a)

print(list[0:20])

Result:
Insert picture description here
3. Continue The
continue statement will go to the next iteration of the loop. The
continue statement is used to ignore certain values, but will not interrupt the loop.

for a in ['-',',',';','\"']:
    text=text.replace(a,' ')#用空格代替

list=[]
for a in text.split(' '):
    if len(a)==0:#如果提取出来的=0就下一次循环
        continue
    list.append(a)

print(list[0:20])

Result:
Insert picture description here
4. Break
break statement will completely interrupt the loop

#将这段话的标点符号去掉，并且把它分开到列表中
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 a in ['-',',',';','\"']:
    text=text.replace(a,' ')#用空格代替

list=[]
for a in text.split(' '):
    if len(a)==0:
        break
    list.append(a)

print(list[0:20])

result:
Insert picture description here

Exercise:

Write a Python program that iterates integers from 1 to 50 (using a for loop). For even integers, append them to the list even_numbers. For odd integers, append them to the odd odd list.

Reminder: range(1,51) represents an integer from 1 to 50

even_number=[]#偶数列表
odd_number=[]#奇数列表

for a in range(1,51):
    if a%2==0:
        even_number.append(a)
    else:
        odd_number.append(a)

print(even_number)
print(odd_number)

result:
Insert picture description here