Saving a Pandas dataframe in fixed format with different column widths

Question

I have a pandas dataframe (df) that looks like this:

   A   B  C
0  1  10  1234
1  2  20  0

I want to save this dataframe in a fixed format. The fixed format I have in mind has different column width and is as follows:

"one space for column A's value then a comma then four spaces for column B's values and a comma and then five spaces for column C's values"

Or symbolically:

-,----,-----

My dataframe above (df) would look like the following in my desired fixed format:

1,  10, 1234
2,  20,    0

How can I write a command in Python that saves my dataframe into this format?

P.S. The dataframe is large and has more than 25 million rows so writing a "for i in rows" loop is not an option. — Javier Bhardt
– Javier Bhardt, Commented Apr 27, 2018 at 18:10
df['B'] = df['B'].apply(lambda t: (' '*(4-len(str(t)))+str(t))) and similar for the third column, then save to csv — mathisfun
– mathisfun, Commented Apr 27, 2018 at 18:11
@mathisfun You are a genius. I loved how simple and efficient this command is. Thank you so much! — Javier Bhardt
– Javier Bhardt, Commented Apr 27, 2018 at 18:23
@mathisfun I wish I could pick your answer as the best answer but since it is posted as a comment but not an answer, I cannot — Javier Bhardt
– Javier Bhardt, Commented Apr 27, 2018 at 18:24

mathisfun · Accepted Answer · 2018-04-27 18:27:09Z

3

df['B'] = df['B'].apply(lambda t: (' '*(4-len(str(t)))+str(t)))
df['C'] = df['C'].apply(lambda t: (' '*(5-len(str(t)))+str(t)))
df.to_csv('path_to_file.csv', index=False)

answered Apr 27, 2018 at 18:27

mathisfun

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