A permutation is a mathematical technique that determines the number of possible arrangements in a set when the order of the arrangements matters.
The permutation feature importance is defined to be the decrease in a model score when a single feature value is randomly shuffled 1.
Formula to calculate permutations.
n is the total number of objects.
r is the number of objects selected.
Example:
Suppose you took 2 cakes from a packet of 6 cakes. Calculate the permutations.
Therefore, the permutations are 30.
