Add functions for getting indicator colors

src/utils/lam-station.js

 import Rainbow from 'rainbowvis.js';
 
+const color_spectrum = ["orange", "yellow", "green"];
+const undef_color = "grey";
+
 class LamStation {
 
   constructor(id, coordinates, avg_speed_dir1, avg_speed_dir2, data) {
@@ -12,7 +15,7 @@ class LamStation {
     this.traffic_vol_dir1 = null;
     this.traffic_vol_dir2 = null;
     this.rainbow = new Rainbow();
-    this.rainbow.setSpectrum("orange", "yellow", "green");
+    this.rainbow.setSpectrum(...color_spectrum);
     this.rainbow.setNumberRange(0.0, 1.0);
     this.data = data
   }
@@ -118,4 +121,12 @@ class LamStation {
 
 }
 
+export function get_color_spectrum() {
+  return color_spectrum.slice();
+}
+
+export function get_undef_color() {
+  return undef_color;
+}
+
 export default LamStation;