How do I convert between a measure of similarity and a measure of difference (distance)?

Question

Is there a general way to convert between a measure of similarity and a measure of distance?

Consider a similarity measure like the number of 2-grams that two strings ha

Answer 1

In the case of Levenshtein distance, you could increase the sim score by 1 for every time the sequences match; that is, 1 for every time you didn't need a deletion, insertion or substitution. That way the metric would be a linear measure of how many characters the two strings have in common.