import “../math/number”;
d3.mean = function(array, f) {
var n = array.length, a, m = 0, i = -1, j = 0; if (arguments.length === 1) { while (++i < n) if (d3_number(a = array[i])) m += (a - m) / ++j; } else { while (++i < n) if (d3_number(a = f.call(array, array[i], i))) m += (a - m) / ++j; } return j ? m : undefined;
};