How to write specific columns of a dataframe to a CSV?

Question

I'm writing a script to reduce a large .xlsx file with headers into a CSV, and then write a new CSV file with only the required columns based on the header names.

import pandas
import csv

df = pandas.read_csv('C:\\Python27\\Work\\spoofing.csv')

time = df["InviteTime (Oracle)"]
orignum = df["Orig Number"]
origip = df["Orig IP Address"]
destnum = df["Dest Number"]

df.to_csv('output.csv', header=[time,orignum,origip,destnum])

The error I'm getting is with that last bit of code, and it says

ValueError: Writing 102 cols but got 4 aliases

I'm sure I'm overlooking something stupid, but I've read over the to_csv documentation on the pandas website and I'm still at a loss. I know I'm misusing the to_csv parameters but I can't seem to get my head around the documentation.

Any help is appreciated, thanks!

score 114 · Accepted Answer · edited Apr 25 '15 at 13:05

114

The way to select specific columns is this -

header = ["InviteTime (Oracle)", "Orig Number", "Orig IP Address", "Dest Number"]
df.to_csv('output.csv', columns = header)

edited Apr 25 '15 at 13:05

Nikita Pestrov

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answered Feb 25 '14 at 16:11

user1827356

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Here is [information from the documentation](http://pandas.pydata.org/pandas-docs/stable/io.html#io-store-in-csv) on the parameters. – tsroten Feb 25 '14 at 16:13
Seems to be a mismatch in column names. You can check your columns with df.columns – user1827356 Feb 25 '14 at 16:20
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Only if one unreasonably repeats it :) – user1827356 Feb 25 '14 at 16:23
Is append feature in df.to_csv? – Hamed Baziyad Mar 07 '18 at 09:03
Refer to this - https://stackoverflow.com/questions/17530542/how-to-add-pandas-data-to-an-existing-csv-file – user1827356 Mar 22 '18 at 14:48

score 2 · Answer 2 · answered Apr 06 '22 at 12:43

column_list=["column_name1", "column_name2", "column_name3", "column_name4"]

#filter the dataframe beforehand
ds[column_list].to_csv('output.csv',index=False)

#or use columns arg
ds.to_csv('output.csv', columns = column_list,index=False)

I provide index=False arg in order to write only column values

How to write specific columns of a dataframe to a CSV?

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