Create a lookup table of names and indexes Note that the indexes will be created in the order they appear. For string this doesnt make much difference but for numbers the index might be different than the actual number that appears in names
create_index_lookuptable(d, player0, player1)
A data frame containing the observations. The other parameters specify the name of the columns
The name of the column of data contains player0
The name of the column of data contains player0
A dataframe of a lookup table with columns Names and Index