Embodiments include method, computer program products and apparatuses for normalizing non-numeric features of files and corresponding apparatus. Aspects include segmenting at least one pair of positive instances of a non-numeric feature of a file into a number of tokens and -comparing the tokens in the at least one pair of positive instances to obtain matching tokens. Aspects also include calculating weights of their matching the file, for the matching tokens, and storing the tokens and their weights in a token base.