Python stdin, readlines. change output order

Question

I am working from a Mac and have a question about a python for look. I am using a .txt file called rectangle.txt and inside the file it looks like this:

abcde
fghij
klmno

I need to read these in using stdin. But this is what I need my program to:

afk
bgl
chm
din
ejo

So far, I have a program that reads all the lines and splits them and prints them out. CODE EDITED

So when I changed my code to this:

for line in sys.stdin.readline():
    ls1 = line
    print ls1

I received the list:

a
b
c
d
e

So now I just need to loop through those other ones, but I can't figure that out

I am running this function from the command line:

python rectangle.py < rectangle.txt

I am trying to learn all of this, so instead of giving me the answer, I would like someone to help explain this to me, in a way hopefully I can understand.

Also, in addition to this .txt file input. My program will also be test with these inputs:

123
456
789

and

A
B
C

All doing the same thing as above. Thank you again in advance for helping me. I have been working on this for hours and can't seem to figure it out.

Answer 1

I'm assuming the input in each line has to be the same length.

In this case have a list of the input strings and for the length of one of these strings loop.

["abcde", "fghij", "kilmn"] from here here what do you notice about the pattern of the first character from each string? "a" + "f" + "k".

Answer 2

The trustworthy zip function comes to help:

>>> lines = ["abc", "def", "ghi"]
>>> result = [''.join(x) for x in zip(*lines)]
>>> result
['adg', 'beh', 'cfi']

Explanation: zip does exactly what you'd expect from it - aggregating an element from each given iterable into a new list. We have to pass zip the iterables separately and not as a list which is what *lines does. In the end we just join the single character array together because we want an array of strings and not an array of an array of characters.