toolkit/javascript/d3/src/scale/linear.js
changeset 47 c0b4a8b5a012
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/scale/linear.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,115 @@
+d3.scale.linear = function() {
+  return d3_scale_linear([0, 1], [0, 1], d3.interpolate, false);
+};
+
+function d3_scale_linear(domain, range, interpolate, clamp) {
+  var output,
+      input;
+
+  function rescale() {
+    var linear = domain.length == 2 ? d3_scale_bilinear : d3_scale_polylinear,
+        uninterpolate = clamp ? d3_uninterpolateClamp : d3_uninterpolateNumber;
+    output = linear(domain, range, uninterpolate, interpolate);
+    input = linear(range, domain, uninterpolate, d3.interpolate);
+    return scale;
+  }
+
+  function scale(x) {
+    return output(x);
+  }
+
+  // Note: requires range is coercible to number!
+  scale.invert = function(y) {
+    return input(y);
+  };
+
+  scale.domain = function(x) {
+    if (!arguments.length) return domain;
+    domain = x.map(Number);
+    return rescale();
+  };
+
+  scale.range = function(x) {
+    if (!arguments.length) return range;
+    range = x;
+    return rescale();
+  };
+
+  scale.rangeRound = function(x) {
+    return scale.range(x).interpolate(d3.interpolateRound);
+  };
+
+  scale.clamp = function(x) {
+    if (!arguments.length) return clamp;
+    clamp = x;
+    return rescale();
+  };
+
+  scale.interpolate = function(x) {
+    if (!arguments.length) return interpolate;
+    interpolate = x;
+    return rescale();
+  };
+
+  scale.ticks = function(m) {
+    return d3_scale_linearTicks(domain, m);
+  };
+
+  scale.tickFormat = function(m) {
+    return d3_scale_linearTickFormat(domain, m);
+  };
+
+  scale.nice = function() {
+    d3_scale_nice(domain, d3_scale_linearNice);
+    return rescale();
+  };
+
+  scale.copy = function() {
+    return d3_scale_linear(domain, range, interpolate, clamp);
+  };
+
+  return rescale();
+};
+
+function d3_scale_linearRebind(scale, linear) {
+  scale.range = d3.rebind(scale, linear.range);
+  scale.rangeRound = d3.rebind(scale, linear.rangeRound);
+  scale.interpolate = d3.rebind(scale, linear.interpolate);
+  scale.clamp = d3.rebind(scale, linear.clamp);
+  return scale;
+}
+
+function d3_scale_linearNice(dx) {
+  dx = Math.pow(10, Math.round(Math.log(dx) / Math.LN10) - 1);
+  return {
+    floor: function(x) { return Math.floor(x / dx) * dx; },
+    ceil: function(x) { return Math.ceil(x / dx) * dx; }
+  };
+}
+
+// TODO Dates? Ugh.
+function d3_scale_linearTickRange(domain, m) {
+  var extent = d3_scaleExtent(domain),
+      span = extent[1] - extent[0],
+      step = Math.pow(10, Math.floor(Math.log(span / m) / Math.LN10)),
+      err = m / span * step;
+
+  // Filter ticks to get closer to the desired count.
+  if (err <= .15) step *= 10;
+  else if (err <= .35) step *= 5;
+  else if (err <= .75) step *= 2;
+
+  // Round start and stop values to step interval.
+  extent[0] = Math.ceil(extent[0] / step) * step;
+  extent[1] = Math.floor(extent[1] / step) * step + step * .5; // inclusive
+  extent[2] = step;
+  return extent;
+}
+
+function d3_scale_linearTicks(domain, m) {
+  return d3.range.apply(d3, d3_scale_linearTickRange(domain, m));
+}
+
+function d3_scale_linearTickFormat(domain, m) {
+  return d3.format(",." + Math.max(0, -Math.floor(Math.log(d3_scale_linearTickRange(domain, m)[2]) / Math.LN10 + .01)) + "f");
+}