writing list of list into a COLUMNED .txt file via python

Question

I have a list that looks like

[["a","b","c","d"],["e","f","g","h"],["i","j","k","l"]]

How can I convert this list of list into a text file that looks like

a  b  c  d
e  f  g  h
i  j  k  l

It seemed straightforward but none of the solution on the web seemed concise and elucidating enough for dummies like me to understand.

Thank you!

Answer 1

Praise the power of comprehensions here:

lst = [["a","b","c","d"],["e","f","g","h"],["i","j","k","l"]]

out = "\n".join([" ".join(sublist) for sublist in lst])
print(out)

This yields

a b c d
e f g h
i j k l

Or, longer, maybe more understandable:

for sublist in lst:
    line = " ".join(sublist)
    print(line)

---

If your elements have different lengths, you could leverage .format():

lst = [["a","b","cde","d"],["e","f","g","h"],["i","j","k","l"]]

out = "\n".join(["".join("{:>5}".format(item) for item in sublst) for sublst in lst])
print(out)

Which would yield

a    b  cde    d
e    f    g    h
i    j    k    l

Answer 2

Posting just to highlight the steps you need to take

l = [['a','b','c','d'], ['e', 'f', 'g', 'h'], ['i', 'j', 'k', 'l']]
with open('my_file.txt', 'w') as f:
    for sub_list in l:
        for elem in sub_list:
            f.write(elem + ' ')
        f.write('\n')