renaming backend, cellxgene to server, client respectively

client/src/util/scaleLinear.js

@@ -0,0 +1,18 @@
+// jshint esversion: 6
+
+// Substitute for a d3 linear scale - less flexible, more performant.
+// Returns a function which will scale a value.
+//
+// Example will scale [0,1] to [-1,1]
+//     var myScale = scaleLinear([0, 1], [-1, 1]);
+//     myScale(0) === -1
+// this is is equivalent to d3.scaleLinear().domain([0,1]).range([-1,1])
+
+export const scaleLinear = (domain, range) => {
+  const domainStart = domain[0];
+  const scale = (range[1] - range[0]) / (domain[1] - domain[0]);
+  const rangeStart = range[0];
+  return function(value) {
+    return (value - domainStart) * scale + rangeStart;
+  };
+};