CODEWITHSUNDEEP
pythonpandaspandas-groupby
Frank Wang
Frank Wang

Reputation: 191

Getting all but the first k rows from a group in a GroupBy object

I have a pandas GroupBy object. I am using head(k) to extract the first k elements of each group into a dataframe and I want to also extract the complement. Each group has a nonconstant size.

Is there any straightforwards way of doing this?

Upvotes: 5

Views: 762

Answers (2)

Scott Boston
Scott Boston

Reputation: 153460

You could try this:

Given:

df = pd.DataFrame({'ID':['a','b','b','c','c','c','d','d','d','d'],
             'Data':np.arange(10)})

   Data ID
0     0  a
1     1  b
2     2  b
3     3  c
4     4  c
5     5  c
6     6  d
7     7  d
8     8  d
9     9  d

df[~df.index.isin(df.groupby('ID').head(2).index)]

Output:

   Data ID
5     5  c
8     8  d
9     9  d

Where df.groupby('ID').head(2) returns:

   Data ID
0     0  a
1     1  b
2     2  b
3     3  c
4     4  c
6     6  d
7     7  d

Upvotes: 6

R Palanivel-Tamilnadu India
R Palanivel-Tamilnadu India

Reputation: 452

Yesy, You can use reindex the new dataframe using the reset_index() method.

Upvotes: 0

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