concat part of string from groupby pandas python

Question

How do i concat part of a date with a file name after doing groupby.
I want to end up with an array: 'hello Jan 2 2014','hello Jan 2 2014'

The results of my code were a surprise.

import pandas as pd
from datetime import datetime
d = {   'File' : pd.Series(['hello', 'what']), 
    'Status' : pd.Series([0., 0.]), 
    'Error' : pd.Series([2., 2.]), 
    'AlertDays' : pd.Series([2., 2.]), 
    'Date' : pd.Series([datetime(2014, 1, 2), datetime(2014, 1, 2)])}
df=pd.DataFrame(d)
df['Date']=pd.to_datetime(df['Date'])
Faildf=df[df.Status==0]
Fx=Faildf.groupby('File')['Date'].max().reset_index()
Fx['concat']=Fx['File'] +' '+ str(Fx['Date'])
#FailArray=Fx['concat'].unique()

why is there more than one date... i thought i lost the others dates by doing the groupby and max? results:

>>> Fx
    File                Date                                             concat
0  hello 2012-05-02 00:00:00  0   2012-05-02 00:00:00\n1   2012-05-02 00:00:...
1   what 2012-05-02 00:00:00  0   2012-05-02 00:00:00\n1   2012-05-02 00:00:...

Alvaro Fuentes · Accepted Answer · 2014-01-13 19:40:14Z

1

The problem is that you are concatenating a pandas Series Fx['File'] with the string representation of a pandas Series str(Fx['Date']), what you need to do is apply the str cast function to the elements of Fx['Date'] like this:

>>> Fx['File'] + " " + Fx['Date'].apply(str)
0    hello 2014-01-02 00:00:00
1     what 2014-01-02 00:00:00

answered Jan 13, 2014 at 19:40

Alvaro Fuentes

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