Create repeated increasing sequence based on values in another column

Question

I have col1 in a pandas df. I want to make col2: col1 col2 1 1 1 2 1 3 1 4 2 2 2 3 2 4 3 3 3 4 4 4 In other words, for each distinct value in col1 I want col2 to be increasing integers that start with the value in col1 and counts up by one until there are no more rows. The data is structured in a way so that max(col1) = 2450: when col1 = 1, there are 2450 rows when col1 = 2, there are 2449 rows when col1 = 2450, there is 1 row JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

You could GroupBy column col1, take the cumcount of the groups and add col1: df['col2'] = df.groupby('col1').cumcount().add(df.col1) Output col1 col2 0 1 1 1 1 2 2 1 3 3 1 4 4 2 2 5 2 3 6 2 4 7 3 3 8 3 4 9 4 4