ticks method

List<num> ticks([ num count = 10 ])

Like ScaleLinear.ticks, but customized for a log scale.

final x = ScaleLog(
  domain: [1, 100],
  range: [0, 960],
  interpolate: interpolateNumber
);
final T = x.ticks(); // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100]

If the base is an integer, the returned ticks are uniformly spaced within each integer power of base; otherwise, one tick per power of base is returned. The returned ticks are guaranteed to be within the extent of the domain. If the orders of magnitude in the domain is greater than count, then at most one tick per power is returned. Otherwise, the tick values are unfiltered, but note that you can use ScaleLog.tickFormat to filter the display of tick labels. If count is not specified, it defaults to 10.

Implementation

List<num> ticks([num count = 10]) {
  final d = domain;
  var u = d[0];
  var v = d[d.length - 1];
  final r = v < u;

  if (r) ([u, v] = [v, u]);

  var i = _logs(u), j = _logs(v);
  num k, t;
  var z = <num>[];

  if (!((base % 1) != 0) && j - i < count) {
    i = i.floor();
    j = j.ceil();
    if (u > 0) {
      for (; i <= j; ++i) {
        for (k = 1; k < base; ++k) {
          t = i < 0 ? k / _pows(-i) : k * _pows(i);
          if (t < u) continue;
          if (t > v) break;
          z.add(t);
        }
      }
    } else {
      for (; i <= j; ++i) {
        for (k = base - 1; k >= 1; --k) {
          t = i > 0 ? k / _pows(-i) : k * _pows(i);
          if (t < u) continue;
          if (t > v) break;
          z.add(t);
        }
      }
    }
    if (z.length * 2 < count) z = array.ticks(u, v, count);
  } else {
    z = array.ticks(i, j, min(j - i, count)).map(_pows).toList();
  }
  return r ? array.reverse(z) : z;
}