Say I have a pandas multi-index like so

                          var_0  var_1
    instances timepoints              
    0         1               1      4
              2               2      5
              3               3      6
              4               5      8
    1         1               1      4
              2               2     55
              3               3      6
              4               3      6
    2         1               1     42
              2               2      5
              3               3      6

How do I truncate it so for every instance I only have the first n timepoints? eg.2

                            var_0  var_1
    instances timepoints              
     0         1               1      4
               2               2      5
     1         1               1      4
               2               2      55
     2         1               1      42
               2               2      5

CodePudding user response：

Assuming multi-index df is df

df_new = df.groupby(level=0).head(2)
print(df_new)

#Haven't tested...it should work..pls, Let me knwo if it doesn't work