Python PANDAS write to csv: how to set decimal point (".", or ",")?

Question

I can't seem to find the option to set the decimal point for floats (".", or ",") when WRITING a DataFrame to a csv file. (Reading is no problem.) My task/problem: I'm publishing a program/script and want all users independent of their OS and language settings to use it and specifically produce a csv output with THE decimal point setting as given in "locale.localeconv()["decimal_point"]". The "float_format" option has not worked for me. Do I need to convert every float to a string and replace the "." with ","? If this is posted somewhere else please excuse my mistake and provide me with the proper link.

Thank you very much for your time and effort!!

This is relevant. I don't see anything specifically helpful, but I would look around here: github.com/pydata/pandas/issues/4668 — Dan Allan
– Dan Allan, Commented Oct 8, 2013 at 14:25

Jeff · Accepted Answer · 2013-10-14 15:07:45Z

4

Not going to be that efficient, but does the job (just to_csv) after)

In [29]: df = DataFrame(dict(A = [1.5,2.5], B = [2.5,3.0]))

In [30]: df
Out[30]: 
     A    B
0  1.5  2.5
1  2.5  3.0

In [31]: df.applymap(lambda x: str(x).replace('.',','))
Out[31]: 
     A    B
0  1,5  2,5
1  2,5  3,0

This should be a bit faster (needs at least 0.12)

In [37]: df.applymap(str).replace(r'\.',',',regex=True)
Out[37]: 
     A    B
0  1,5  2,5
1  2,5  3,0

edited Oct 14, 2013 at 15:07

answered Oct 8, 2013 at 19:31

Jeff

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4 Comments

tryptofame Over a year ago

The first answer (using the lambda function) worked, the second did not ("TypeError: replace() got an unexpected keyword argument 'regex'" using Python 2.7.3). It is fast enough!

Jeff Over a year ago

you need at least 0.12 for 2nd version, IIRC

Jeff Over a year ago

note that this feature is now in 0.16.0 (releasing March 22); you can specify a decimal separator in to_csv()

Uvar Over a year ago

years later and on a completely different issue, but you still solved it.. After transposing a dataframe (rotated = df.T), something changed in the internal representation, which caused writing to csv to fail with its decimal separator. First doing the applymap worked like a charm. Interesting for a friday afternoon project, but for now, mighty big thanks, sir!

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