--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/layout/histogram.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,102 @@
+d3.layout.histogram = function() {
+  var frequency = true,
+      valuer = Number,
+      ranger = d3_layout_histogramRange,
+      binner = d3_layout_histogramBinSturges;
+
+  function histogram(data, i) {
+    var bins = [],
+        values = data.map(valuer, this),
+        range = ranger.call(this, values, i),
+        thresholds = binner.call(this, range, values, i),
+        bin,
+        i = -1,
+        n = values.length,
+        m = thresholds.length - 1,
+        k = frequency ? 1 : 1 / n,
+        x;
+
+    // Initialize the bins.
+    while (++i < m) {
+      bin = bins[i] = [];
+      bin.dx = thresholds[i + 1] - (bin.x = thresholds[i]);
+      bin.y = 0;
+    }
+
+    // Fill the bins, ignoring values outside the range.
+    i = -1; while(++i < n) {
+      x = values[i];
+      if ((x >= range[0]) && (x <= range[1])) {
+        bin = bins[d3.bisect(thresholds, x, 1, m) - 1];
+        bin.y += k;
+        bin.push(data[i]);
+      }
+    }
+
+    return bins;
+  }
+
+  // Specifies how to extract a value from the associated data. The default
+  // value function is `Number`, which is equivalent to the identity function.
+  histogram.value = function(x) {
+    if (!arguments.length) return valuer;
+    valuer = x;
+    return histogram;
+  };
+
+  // Specifies the range of the histogram. Values outside the specified range
+  // will be ignored. The argument `x` may be specified either as a two-element
+  // array representing the minimum and maximum value of the range, or as a
+  // function that returns the range given the array of values and the current
+  // index `i`. The default range is the extent (minimum and maximum) of the
+  // values.
+  histogram.range = function(x) {
+    if (!arguments.length) return ranger;
+    ranger = d3.functor(x);
+    return histogram;
+  };
+
+  // Specifies how to bin values in the histogram. The argument `x` may be
+  // specified as a number, in which case the range of values will be split
+  // uniformly into the given number of bins. Or, `x` may be an array of
+  // threshold values, defining the bins; the specified array must contain the
+  // rightmost (upper) value, thus specifying n + 1 values for n bins. Or, `x`
+  // may be a function which is evaluated, being passed the range, the array of
+  // values, and the current index `i`, returning an array of thresholds. The
+  // default bin function will divide the values into uniform bins using
+  // Sturges' formula.
+  histogram.bins = function(x) {
+    if (!arguments.length) return binner;
+    binner = typeof x === "number"
+        ? function(range) { return d3_layout_histogramBinFixed(range, x); }
+        : d3.functor(x);
+    return histogram;
+  };
+
+  // Specifies whether the histogram's `y` value is a count (frequency) or a
+  // probability (density). The default value is true.
+  histogram.frequency = function(x) {
+    if (!arguments.length) return frequency;
+    frequency = !!x;
+    return histogram;
+  };
+
+  return histogram;
+};
+
+function d3_layout_histogramBinSturges(range, values) {
+  return d3_layout_histogramBinFixed(range, Math.ceil(Math.log(values.length) / Math.LN2 + 1));
+}
+
+function d3_layout_histogramBinFixed(range, n) {
+  var x = -1,
+      b = +range[0],
+      m = (range[1] - b) / n,
+      f = [];
+  while (++x <= n) f[x] = m * x + b;
+  return f;
+}
+
+function d3_layout_histogramRange(values) {
+  return [d3.min(values), d3.max(values)];
+}