Change column values using pandas

Question

I am using pandas and trying to replace a value with another value. What am I doing wrong?

Source

Drive-By
Referral
Website
Radio

My snippet:

import pandas as pd

second = pd.read_csv('T:/pythonfiles/result2.csv')
second['Source'] = second['Source'].replace('Drive-By', 'Drive-by')

Error:

File "pandas/src/hashtable_class_helper.pxi", line 732, in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:13161)
File "pandas/src/hashtable_class_helper.pxi", line 740, in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:13115)
KeyError: 'Source'

KeyError: 'Source' means that Source is not a valid header name within your data file. Are you sure you have the column names correct? — Chuck
– Chuck, Commented Jan 26, 2017 at 20:51
Could you post an output of print(second.columns.tolist()) after you read the CSV file (read_csv()...) - this will help toi understand what is wrong with your columns — MaxU - stand with Ukraine
– MaxU - stand with Ukraine, Commented Jan 26, 2017 at 20:55
Thanks @ Charles Morris. There is a semicolon in front of Source. — Jason Smith
– Jason Smith, Commented Jan 26, 2017 at 20:56

Community · Accepted Answer · 2017-05-23 12:24:17Z

1

I believe that you can use the following as found in this answer:

second.replace({'Drive-By': 'Drive-by'}, regex=True)

This would normally replace the value in all columns, but if you don't have 'Drive-By' recurring in other columns, this should work ok.

However, your error message suggests that you have issues with 'Source' not being recognized as a key in the table.

edited May 23, 2017 at 12:24

CommunityBot

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answered Jan 26, 2017 at 20:54

Fruitspunchsamurai

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