CODEWITHSUNDEEP
pythonpandasdictionarypandas-groupby
CandleWax
CandleWax

Reputation: 2219

How to select the previous row in a group with pandas?

I need to select the row previous to when discharge_location is Readmit within a group. Then set the ID and Discharge_location to a dictionary.

sample df

ID     admit     discharge    discharge_location   first
20     3-4-2018  3-6-2018     Home                 1
20     2-2-2018  2-6-2018     Home                 0
20     2-5-2018  2-23-2018    Readmit              0
30     1-2-2018  2-3-2018     Rehab                1
30     1-15-2018 1-18-2018    Readmit              0
30     1-20-2018 1-24-2018    Home                 0
40     1-20-2018 1-24-2018    Home                 0
40     1-20-2018 1-24-2018    Home                 0
40     1-20-2018 1-24-2018    Home                 0

final result

ID    Discharge_location
20    Home
30    Rehab

Upvotes: 2

Views: 542

Answers (1)

BENY
BENY

Reputation: 323286

IIUC

df.loc[df[df.discharge_location=='Readmit'].index-1]
Out[1519]: 
   ID     admit discharge discharge_location  first
1  20  2-2-2018  2-6-2018               Home      0
3  30  1-2-2018  2-3-2018              Rehab      1

From MartyB

df.loc[df[df.discharge_location=='Readmit'].index-1][['ID','discharge_location']].set_index('ID').to_dict()

Upvotes: 1

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