[gajomi]

This calculation is underdetermined, and there isn't any algorithm that would specify "it", since there are many functions that would satisfy the requirements. In general this is a hard problem of induction. In a more limited context you might think about adding regularizations that will make the function better determined. Choosing these and implementing them may not be trivial.

If you are talking paths generated from touch gestures there is some research on that topic.

[art-w]

People working on program synthesis consider the Occam razor "the shortest/simplest code" to be a good heuristic of the intended function (given a good test case.) Their main problem is the exponential space search.