Counter / Index in a pandas dataframe based on column

Question

I have the following dataframe:

df
Date Application Weekday
02.01 A           3
02.01 B           3
03.01 A           4
03.01 B           4
04.01 A           5
04.01 B           5
05.01 A           6
05.01 B           6

And I want to filter out the weekdays: 5,6 and want to have a new index based on the dates, that means i would like to get:

df
Date Application Weekday Index
02.01 A           3        1
02.01 B           3        1 
03.01 A           4        2
03.01 B           4        2

How can i get that?

jezrael · Accepted Answer · 2020-03-12 09:50:32Z

1

Use boolean indexing and create new column with DataFrame.assign and factorize, lambda function is necessary for processing filtered data:

df = df[df['Weekday'].lt(5)].assign(Index = lambda x: pd.factorize(x['Date'])[0] + 1)
print (df)
   Date Application  Weekday  Index
0  2.01           A        3      1
1  2.01           B        3      1
2  3.01           A        4      2
3  3.01           B        4      2

edited Mar 12, 2020 at 9:50

answered Mar 12, 2020 at 9:45

jezrael

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PV8 Over a year ago

I get the error: ValueError: Length of values does not match length of index

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