Deleting consecutive rows in a pandas dataframe with the same value-CodePudding

How can I delete only the three consecutive rows in a pandas dataframe that have the same value (in the example below, this would be the integer "4").

Consider the following code:

import pandas as pd

df = pd.DataFrame({
    'rating': [4, 4, 3.5, 15, 5 ,4,4,4,4,4 ]
})

   rating
0  4.0
1  4.0
2  3.5
3  15.0
4  5.0
5  4.0
6  4.0
7  4.0
8  4.0
9  4.0

I would like to get the following result as output with the three consecutive rows containing the value "4" being removed:

CodePudding user response：

Use GroupBy.cumcount for counter and filter in rows in boolean indexing:

#filter consecutive groups less like 2 (python count from 0)
df= df[df.groupby(df['rating'].ne(df['rating'].shift()).cumsum()).cumcount().lt(2)]
print (df)
   rating
0     4.0
1     4.0
2     3.5
3    15.0
4     5.0
5     4.0
6     4.0

CodePudding user response：

first get a group each time a new value exists, then use GroupBy.head

new_df = df.groupby(df['rating'].ne(df['rating'].shift()).cumsum()).head(2)
print(new_df)

   rating
0     4.0
1     4.0
2     3.5
3    15.0
4     5.0
5     4.0
6     4.0