I am trying to count all the instances of all values of col_a
col_a A B C A D B A
Is there one line of code I can use that would tell me how many times each value (A,B,C,D) exist in that column?
So, the solution for this can be value_counts
Or, you can use groupby with size:
>>> df.groupby('col_a').size()col_aA 3B 2C 1D 1dtype: int64>>>