CODEWITHSUNDEEP
pythondataframe
lordy
lordy

Reputation: 630

Drop rows from dataframe with the values occuring only once in the whole column

I have a data frame like this:

import pandas as pd

data = [['bob', 1], ['james', 4], ['joe', 4], ['joe', 1], ['bob', 3], ['wendy', 5], ['joe', 7]]
df = pd.DataFrame(data, columns=['name', 'score'])
print(df)

Looking like:

    name  score
0    bob      1
1  james      4
2    joe      4
3    joe      1
4    bob      3
5  wendy      5
6    joe      7

I would like to drop all persons with only a single occurrence in a Pythonic way i.e. the result should look like:

    name  score
0    bob      1
2    joe      4
3    joe      1
4    bob      3
6    joe      7

... and how would I do the same with entries that only have 1 or 2 occurrences? i.e.

    name  score
2    joe      4
3    joe      1
6    joe      7

Upvotes: 1

Views: 237

Answers (1)

sushanth
sushanth

Reputation: 8302

try this, DataFrameGroupBy.nunique to get count of unique elements in each group & apply isin to filter occurrences.

g = df.groupby(['name'])['score'].transform('nunique')

df[~g.isin([1])]

  name  score
0  bob      1
2  joe      4
3  joe      1
4  bob      3
6  joe      7

df[~g.isin([1,2])]

  name  score
2  joe      4
3  joe      1
6  joe      7

Upvotes: 2

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