Bar graph added.

node_modules/vega-functions/src/functions/geo.js

@@ -0,0 +1,23 @@
+import {getScale} from '../scales';
+import {
+  geoArea as area,
+  geoBounds as bounds,
+  geoCentroid as centroid
+} from 'd3-geo';
+
+function geoMethod(methodName, globalMethod) {
+  return function(projection, geojson, group) {
+    if (projection) {
+      // projection defined, use it
+      const p = getScale(projection, (group || this).context);
+      return p && p.path[methodName](geojson);
+    } else {
+      // projection undefined, use global method
+      return globalMethod(geojson);
+    }
+  };
+}
+
+export const geoArea = geoMethod('area', area);
+export const geoBounds = geoMethod('bounds', bounds);
+export const geoCentroid = geoMethod('centroid', centroid);