If you want to do something with every item in the list, you can use a for loop. The command line is:
for variable in list_name:
A variable name follows the for keyword; it will be assigned the value of each list item in turn.
Then in list_namedesignates list_name as the list the loop will work on. The line ends with a colon (:) and the indented code that follows it will be executed once per item in the list.
What does this code?
>>> my_list = [1,9,3,8,5,7]
>>>
>>> for number in my_list:
... # Your code here
... print number*2
...
...
The for loop will automatically execute your code as many times as there are items in my_list.The result is:
...
2
18
6
16
10
14
>>>
If your list is a jumbled mess, you may need to sort() it.Note that .sort() modifies the list rather than returning a new list.
Write a forloop that iterates over start_list = [5, 3, 1, 2, 4] and .append()s each number squared (x ** 2) to square_list(initialized to empty list).
Then sort square_list.
>>> start_list = [5, 3, 1, 2, 4]
>>> square_list = []
>>>
>>>
>>> for number in start_list:
... n=star_list[number-1]
... square_list.append(n**2)
...
>>> #Now we reordenate the list
...
>>> square_list.sort()
>>> print square_list
[1, 4, 9, 16, 25]
>>>
over `start_list=[5, 3, 1, 2, 4] and .append()s each number squared (x ** 2) to `square_list` (which is initialized to empty list).
Then sort square_list.
Use a for loop to print out all of the elements in the list names.
names = ["Adam","Alex","Mariah","Martine","Columbus"]
>>> names = ["Adam","Alex","Mariah","Martine","Columbus"]
>>>
>>> for name in names:
... print name
...
Adam
Alex
Mariah
Martine
Columbus
>>>
You can also use the forloop with strings:
We are going to print only the "i" letters for a string. Run this code and analyze what happend:
word = "Programming is fun!"
for letter in word:
# Only print out the letter i
if letter == "i":
print letter