Pandas: get the first occurrence grouping by keys
I think you need GroupBy.first
:
df.groupby(["id", "id2"])["timestamp"].first()
Or drop_duplicates
:
df.drop_duplicates(subset=['id','id2'])
For same output:
df1 = df.groupby(["id", "id2"], as_index=False)["timestamp"].first()
print (df1)
id id2 timestamp
0 10 a1 2017-07-12 13:37:00
1 10 a2 2017-07-12 19:00:00
2 11 a1 2017-07-12 13:37:00
df1 = df.drop_duplicates(subset=['id','id2'])[['id','id2','timestamp']]
print (df1)
id id2 timestamp
0 10 a1 2017-07-12 13:37:00
1 10 a2 2017-07-12 19:00:00
2 11 a1 2017-07-12 13:37:00