Printing a large list in multiple lines

Question

Is there a good way to print a large list in multiple lines? Assume that a list has 10000 elements and by writing that to a file it goes all in a single line which is difficult for text editors to open that.

I know I can iterate over the size with a counter and print \n after each 1000 elements. For example:

my_list = [0,1,2,3,4,5,6,7,8,9]
x = 0
for i in my_list:
    if x % 5 == 0:
        print()
    print(i, end='')
    x += 1

prints

01234
56789

I wonder if there is a Python function for that to do that in a more efficient way.

Do the answers to this [question](https://stackoverflow.com/questions/312443/how-do-you-split-a-list-into-evenly-sized-chunks) help at all? — quamrana, May 13 '22 at 11:37

score 1 · Accepted Answer · answered May 13 '22 at 11:41

You can loop over the list in chunks and print each chunk to the file:

my_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
chunk_size = 3
with open('myfile.txt', 'w') as f:
    for i in range(0, len(my_list), chunk_size):
        chunk = my_list[i:i+chunk_size]
        print(*chunk, file=f)

This results in the file content

You can change the print() line to format the output to your liking. To e.g. remove the spaces between the numbers, use print(*chunk, sep='', file=f).

Neil · Answer 2 · 2022-05-13T11:51:10.247

In terms of number of lines of code, hard to beat this:

chunk_size = 10
result = '\n'.join(str(my_list)[i:i+chunk_size] for i in range(0, len(str(a)), chunk_size))
print(result)

Note that this does still print the commas.

Looking at your attempted solution:

my_list = [0,1,2,3,4,5,6,7,8,9]
x = 0
for i in my_list:
    if x % 5 == 0:
        print()
    print(i, end='')
    x += 1

Can be improved using enumerate:

my_list = [0,1,2,3,4,5,6,7,8,9]

for x, i in enumerate(my_list):
    if x % 5 == 0:
        print()
    print(i, end='')

Note that using "i" for the items here and "x" for the index is pretty gross though, since "i" is normally the index

Actually even the x%5 can be pulled into the print statement with a ternary expression:

for x, i in enumerate(my_list):
    print(i, end='\n' if x%5==0 else '')

Printing a large list in multiple lines

2 Answers2