Python pandas preserving decimal commas in the output csv file

Question

I'm using pandas library to do some operations on .csv file.

Input file input.csv:

    A    B   
   1,2  2,2
   3,5  5,4

My code:

import pandas as pd

df = read_csv('input.csv', sep = ';', encoding = 'ANSI', decimal = ',')
'''
some operations on cells like adding, multiplying...  
'''

df.to_csv('output.csv', sep = ';', encoding = 'ANSI', index = False)

And here is how my output.csv looks like:

    A    B    C   
   1.2  2.2  6.5
   3.5  5.4  7.8

But is there any way to keep my decimal separator as comma like there was in the input.csv?

Here is how output.csv should look like:

    A    B    C   
   1,2  2,2  6,5
   3,5  5,4  7,8

I have tried something like this but it didn't work:

df = df.astype(str).replace('.',',')

harpan · Accepted Answer · 2018-07-31 00:04:06Z

4

Method 1

You can use:

df.to_csv('output.csv', sep = ';', encoding='ANSI', index=False, decimal=",")

Method 2

As an alternative you can also use.

df = df.applymap(lambda x: str(x).replace('.',','))

instead of df = df.astype(str).replace('.',',')

It would give:

      A   B   C
0   1,2 2,2 6,5
1   3,5 5,4 7,8

And then

df.to_csv('output.csv', sep = ';', encoding = 'ANSI', index=False)

edited Jul 31, 2018 at 0:04

answered Jul 30, 2018 at 19:48

harpan

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4 Comments

sundance Over a year ago

This is a built-in feature to DataFrame.to_csv. If it's not working for you there is likely an underlying reason (e.g., outdated version of Pandas, your types are actually strings and not floats, etc.) that you should diagnose

sundance Over a year ago

You should add a note about the decimal argument to your answer so that others looking to solve this problem are aware of the built-in option, in case their dataset is too big to loop over every element.

harpan Over a year ago

@sundance, sounds like a god bit. Answer edited. Thanks.

mactonight95 Over a year ago

I have pandas v0.23.3, except floats I store in my .csv files a few strings if that's the case.

harpan · Accepted Answer · 2018-07-31 00:04:35Z

2

Like pandas.read_csv, DataFrame.to_csv also has a decimal argument:

df.to_csv('output.csv', sep = ';', encoding='ANSI', index=False, decimal=",")

edited Jul 31, 2018 at 0:04

harpan

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answered Jul 30, 2018 at 19:43

sundance

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2 Comments

mactonight95 Over a year ago

It doesn't work for me, I'm still having dots in my output.csv

sundance Over a year ago

Works fine on my machine. What version of Python and Pandas are you running?

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