Bar graph added.

node_modules/vega-statistics/src/regression/points.js

@@ -0,0 +1,44 @@
+export function points(data, x, y, sort) {
+  data = data.filter(d => {
+    let u = x(d), v = y(d);
+    return u != null && (u = +u) >= u && v != null && (v = +v) >= v;
+  });
+
+  if (sort) {
+    data.sort((a, b) => x(a) - x(b));
+  }
+
+  const n = data.length,
+        X = new Float64Array(n),
+        Y = new Float64Array(n);
+
+  // extract values, calculate means
+  let i = 0, ux = 0, uy = 0, xv, yv, d;
+  for (d of data) {
+    X[i] = xv = +x(d);
+    Y[i] = yv = +y(d);
+    ++i;
+    ux += (xv - ux) / i;
+    uy += (yv - uy) / i;
+  }
+
+  // mean center the data
+  for (i=0; i<n; ++i) {
+    X[i] -= ux;
+    Y[i] -= uy;
+  }
+
+  return [X, Y, ux, uy];
+}
+
+export function visitPoints(data, x, y, callback) {
+  let i = -1, u, v;
+
+  for (let d of data) {
+    u = x(d);
+    v = y(d);
+    if (u != null && (u = +u) >= u && v != null && (v = +v) >= v) {
+      callback(u, v, ++i);
+    }
+  }
+}