[FIXED] Count the group occurrences

Issue

I have dataframe

      id webpage
       1   google
       2    bing
       3   google
       4   google
       5   yahoo
       6   yahoo
       7   google
       8   google

Would like to count the groups

like

       id webpage count
       1   google  1
       2    bing   2
       3   google  3
       4   google  3
       5   yahoo   4
       6   yahoo   4
       7   google  5
       8   google  5

I have tried using the cumcount or ngroup when using groupby it is grouping all occurrence.

Solution

I believe you need to cumsum() over the state transitions. Every time webpage differs from the previous row you increase your count.

df["count"] = (df.webpage != df.webpage.shift()).cumsum()

Answered By - filippo