How to delete every 0.2-th row in a pandas dataframe?-CodePudding

df_o = pd.DataFrame(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o'])

I would like to continuously delete 4 consecutive rows but always spare the fifth in the dataframe above. The final result should be:

df_o = pd.DataFrame(['e', 'j', 'o'])

My idea df_o = df_o.drop(df_o.iloc[::0.2].index)does not work. It works well for deleting every n-th row if n is an integer, but not for my case.

CodePudding user response：

Try this:

df_o.groupby(np.arange(len(df_o.index))//5).last()

Output:

CodePudding user response：

You could use loc:

import numpy as np
out = df_o.loc[np.arange(1, len(df_o) 1)%5==0, 0].tolist()

Output:

['e', 'j', 'o']

CodePudding user response：

Keep it simple: slice!

df_o.iloc[4::5]

Generalization:

N = 5
df_o.iloc[N-1::N]

Output: