In PANDAS, how to get the index of a known value?

Question

If we have a known value in a column, how can we get its index-value? For example:

In [148]: a = pd.DataFrame(np.arange(10).reshape(5,2),columns=[\'c1\',\'c2\'         


        

Answer 1

Using the .loc[] accessor:

In [25]: a.loc[a['c1'] == 8].index[0]
Out[25]: 4

Can also use the get_loc() by setting 'c1' as the index. This will not change the original dataframe.

In [17]: a.set_index('c1').index.get_loc(8)
Out[17]: 4