[python] How to get row number in dataframe in Pandas?

df.loc[df.LastName == 'Smith']

will return the row

    ClientID    LastName
1   67          Smith

and

df.loc[df.LastName == 'Smith'].index

will return the index

Int64Index([1], dtype='int64')

NOTE: Column names 'LastName' and 'Last Name' or even 'lastname' are three unique names. The best practice would be to first check the exact name using df.columns. If you really need to strip the column names of all the white spaces, you can first do

df.columns = [x.strip().replace(' ', '') for x in df.columns]