A method of analyzing a string-pattern includes defining a minimum length (Lmin—1) of substrings (STR_A_B) to be considered; defining a maximum length (Lmax—1) of substrings (STR_A_B) to be considered; with a computer, searching the string-pattern for substrings (STR_A_B) with a length in an interval between the minimum length (Lmin—1) and the maximum length (Lmax—1); counting an occurrence (Occ_A_B) of each substring (STR_A_B) found with a length in the interval between the minimum length (Lmin—1) and the maximum length (Lmax—1); and pruning away a number of the substrings (STR_A_B) that meet one or more criteria. The criteria are selected from the group consisting of (1) being contained inside the maximum substring (STR_A_C) in a subset (SET_A) of substrings (STR_A_B), (2) being shorter than the maximum substring (STR_A_C), (3) occurring with a same frequency as the maximum substring (STR_A_C), and combinations thereof.