Function d3_number

d3-3.2.8/d3.js:77–79

(x)

    return s;
  };
  function d3_number(x) {
    return x != null && !isNaN(x);
  }
  d3.mean = function(array, f) {
    var n = array.length, a, m = 0, i = -1, j = 0;
    if (arguments.length === 1) {