Specifying a specific date value in python pandas dataframe

Question

I have a dataframe df, with two columns, GROUP_ID={A,B} and ACTION_DATE. What I want to do is to replace the ACTION_DATE value to 03/31/2006, if the GROUP_ID's value is B. Data type of ACTION_DATE is datetime64[ns].

So, I tried the following.

df[(df.GROUP_ID == 'B')].ACTION_DATE = '03/31/2006 0:00'

The above line runs with no errors, but the resulting dataframe remains unchanged.

Could someone point out what I am missing?

GROUP_ID ACTION_DATE A 2005-05-30 A 2005-05-30 A 2005-05-30 B 2005-05-30 B 2005-05-30 B 2005-05-30 — DavidH, May 04 '15 at 17:33

score 2 · Answer 1 · edited May 04 '15 at 16:18

2

Try this:

df.loc[df.GROUP_ID == 'B', 'ACTION_DATE'] = '03/31/2006 0:00'

edited May 04 '15 at 16:18

isherwood

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answered May 04 '15 at 14:51

Venkat R

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Thanks. I tried your suggestion, and I got this error message --- AttributeError: 'str' object has no attribute 'view' – DavidH May 04 '15 at 15:41

score 0 · Answer 2 · answered May 04 '15 at 16:05

0

Can you try this

df['ACTION_DATE'][df['GROUP_ID'] == 'B'] = '03/31/2006 0:00'

At times placing the column upfront works...

answered May 04 '15 at 16:05

Kathirmani Sukumar

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DavidH · Answer 3 · 2015-05-19T20:22:15.087

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The following worked:

import pandas as pd
df[(df.GROUP_ID == 'B')].ACTION_DATE = pd.to_datetime('03/31/2006 0:00')

edited May 19 '15 at 20:22

answered May 18 '15 at 17:44

DavidH

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Specifying a specific date value in python pandas dataframe

3 Answers3