[python] Pandas (python): How to add column to dataframe for index?

The index that I have in the dataframe (with 30 rows) is of the form:

Int64Index([171, 174,173, 172, 199..............
        ....175, 200])

The index is not strictly increasing because the data frame is the output of a sort(). I want to have add a column which is the series:

[1, 2, 3, 4, 5......................., 30]

How should I go about doing that?

Thanks.

How about:

df['new_col'] = range(1, len(df) + 1)

Alternatively if you want the index to be the ranks and store the original index as a column:

df = df.reset_index()

I stumbled on this question while trying to do the same thing (I think). Here is how I did it:

df['index_col'] = df.index

You can then sort on the new index column, if you like.