Bar graph added.

node_modules/vega-statistics/src/dotbin.js

@@ -0,0 +1,63 @@
+// Dot density binning for dot plot construction.
+// Based on Leland Wilkinson, Dot Plots, The American Statistician, 1999.
+// https://www.cs.uic.edu/~wilkinson/Publications/dotplots.pdf
+export default function(array, step, smooth, f) {
+  f = f || (_ => _);
+
+  let i = 0, j = 1,
+      n = array.length,
+      v = new Float64Array(n),
+      a = f(array[0]),
+      b = a,
+      w = a + step,
+      x;
+
+  for (; j<n; ++j) {
+    x = f(array[j]);
+    if (x >= w) {
+      b = (a + b) / 2;
+      for (; i<j; ++i) v[i] = b;
+      w = x + step;
+      a = x;
+    }
+    b = x;
+  }
+
+  b = (a + b) / 2;
+  for (; i<j; ++i) v[i] = b;
+
+  return smooth ? smoothing(v, step + step / 4) : v;
+}
+
+// perform smoothing to reduce variance
+// swap points between "adjacent" stacks
+// Wilkinson defines adjacent as within step/4 units
+function smoothing(v, thresh) {
+  let n = v.length,
+      a = 0,
+      b = 1,
+      c, d;
+
+  // get left stack
+  while (v[a] === v[b]) ++b;
+
+  while (b < n) {
+    // get right stack
+    c = b + 1;
+    while (v[b] === v[c]) ++c;
+
+    // are stacks adjacent?
+    // if so, compare sizes and swap as needed
+    if (v[b] - v[b-1] < thresh) {
+      d = b + ((a + c - b - b) >> 1);
+      while (d < b) v[d++] = v[b];
+      while (d > b) v[d--] = v[a];
+    }
+
+    // update left stack indices
+    a = b;
+    b = c;
+  }
+
+  return v;
+}