CODEWITHSUNDEEP
pythonpandasnanmin
weizer
weizer

Reputation: 1117

How to create a column based on the min date of multiple columns?

enter image description here

print (df)
      Event1     Event2     Event3
0  7/27/2014        NaN        NaN
1   3/5/2016        NaN   2/1/2013
2  5/13/2017  5/10/2013        NaN
3        NaN        NaN  4/28/2014
4        NaN  5/12/2013   3/6/2016
5        NaN        NaN        NaN

Hi all,

I have 3 columns in my pandas dataframe, I want to create a new column to show the minimum date among Event 1, Event 2, and Event 3. If there is no date in all the 3 columns, then print NaN as shown in the last row of the screenshot above.

The last column in the screenshot (New column) is the expected output. Any advise or help will be greatly appreciated!

Upvotes: 1

Views: 407

Answers (1)

jezrael
jezrael

Reputation: 862441

Filter columns with Event with DataFrame.filter, convert to datetimes and get minimal values, last for original format use Series.dt.strftime:

df['new'] = (df.filter(like='Event')
               .apply(pd.to_datetime)
               .min(axis=1)
               .dt.strftime('%m/%d/%Y'))
print (df)
      Event1     Event2     Event3         new
0  7/27/2014        NaN        NaN  07/27/2014
1   3/5/2016        NaN   2/1/2013  02/01/2013
2  5/13/2017  5/10/2013        NaN  05/10/2013
3        NaN        NaN  4/28/2014  04/28/2014
4        NaN  5/12/2013   3/6/2016  05/12/2013
5        NaN        NaN        NaN         NaN

Upvotes: 3

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