Add a sequence number to each element in a group using python

by

I stumbled upon the answer which was embarrassingly simple. The groupby statement has a ‘cumcount()’ option which will enumerate group items.

df['sequence']=df.groupby('patient').cumcount()

The caveat is that the records have to be in the order you want them enumerated.

More Related Contents:

  1. Add a sequential counter column on groups to a pandas dataframe
  2. Get statistics for each group (such as count, mean, etc) using pandas GroupBy?
  3. How do I create a new column from the output of pandas groupby().sum()?
  4. Pandas GroupBy.apply method duplicates first group
  5. Pandas groupby multiple fields then diff
  6. Pandas Groupby Range of Values
  7. How to access pandas groupby dataframe by key
  8. Pandas GroupBy and select rows with the minimum value in a specific column
  9. How to group a pandas dataframe by a defined time interval?
  10. Pandas: resample timeseries with groupby
  11. Make Pandas groupby act similarly to itertools groupby
  12. Python pandas – filter rows after groupby
  13. Pandas groupby nlargest sum
  14. Python Pandas How to assign groupby operation results back to columns in parent dataframe?
  15. why does pandas rolling use single dimension ndarray
  16. pandas – find first occurrence
  17. python pandas groupby() result
  18. Group dataframe and get sum AND count?
  19. group by week in pandas
  20. Pivot Tables or Group By for Pandas?
  21. Pandas Correlation Groupby
  22. Enumerate each row for each group in a DataFrame
  23. Pandas aggregate count distinct
  24. Is there an “ungroup by” operation opposite to .groupby in pandas?
  25. Pandas groupby with bin counts
  26. get first and last values in a groupby
  27. Pandas groupby and qcut
  28. Pandas groupby and aggregation output should include all the original columns (including the ones not aggregated on)
  29. how to convert monthly data to quarterly in pandas
  30. How to get number of groups in a groupby object in pandas?

Leave a Comment