For loops (novice)

Question

I recently started learning Python, and the concept of for loops is still a little confusing for me. I understand that it generally follows the format for x in y

Answer 1

Bear in mind that the 'list' part of the Python can be any iterable sequence.

Examples:

A string:

for c in 'abcdefg':
   # deal with the string on a character by character basis...

A file:

with open('somefile','r') as f:
    for line in f:
         # deal with the file line by line

A dictionary:

d={1:'one',2:'two',3:'three'}
for key, value in d.items():
   # deal with the key:value pairs from a dict

A slice of a list:

l=range(100)
for e in l[10:20:2]:
    # ever other element between 10 and 20 in l 

etc etc etc etc

So it really is a lot deeper than 'just some list'

As others have stated, just set the iterable to be what you want it to be for your example questions:

 for e in (i*i for i in range(10)):
     # the squares of the sequence 0-9...

 l=[1,5,10,15]
 for i in (i*2 for i in l):
     # the list l as a sequence * 2...