Number of unique values per column by group

Question

Consider the following dataframe:

      A      B  E
0   bar    one  1
1   bar  three  1
2  flux    six  1
3  flux  three  2
4   foo   five  2
5   foo    one          


        

Answer 1

I encountered the same problem. Upgrading pandas to the latest version solved the problem for me.

df.groupby('A').nunique()

The above code did not work for me in Pandas version 0.19.2. I upgraded it to Pandas version 0.21.1 and it worked.

You can check the version using the following code:

print('Pandas version ' + pd.__version__)