Moving counts

x mcount y     mcount[x;y]

Where

• x is a positive int atom
• y is a numeric list

returns the x-item moving counts of the non-null items of y. The first x items of the result are the counts so far, and thereafter the result is the moving count.

q)3 mcount 0 1 2 3 4 5
1 2 3 3 3 3
q)3 mcount 0N 1 2 3 0N 5
0 1 2 3 2 2

mcount is a uniform function.