To get all indices that matches ‘Smith’
>>> df[df['LastName'] == 'Smith'].index Int64Index(, dtype='int64')
or as a numpy array
>>> df[df['LastName'] == 'Smith'].index.to_numpy() # .values on older versions array()
or if there is only one and you want the integer, you can subset
>>> df[df['LastName'] == 'Smith'].index 1
You could use the same boolean expressions with
.loc, but it is not needed unless you also want to select a certain column, which is redundant when you only want the row number/index.