Fixed font.

lib/filters.js

@@ -42,6 +42,10 @@ export const refFilter = data => {
   return Object.keys(map).map(key => ({ x: key, y: map[key], w: links[key] }));
 };
 
+export const emptyFilter = data => {
+  return data.map(item => (item.x ? item : null)).filter(n => n);
+};
+
 export const percentFilter = data => {
   const total = data.reduce((n, { y }) => n + y, 0);
   return data.map(({ x, y, ...props }) => ({ x, y, z: total ? (y / total) * 100 : 0, ...props }));