do not reset color-by when subsetting world (#636)

* do not reset colors when subsetting to world

* revert diffexp state change

client/src/util/stateManager/colorHelpers.js

@@ -0,0 +1,122 @@
+/*
+Helper functions for the embedded graph colors
+*/
+import _ from "lodash";
+import * as d3 from "d3";
+import { interpolateRainbow, interpolateCool } from "d3-scale-chromatic";
+import * as globals from "../../globals";
+import parseRGB from "../parseRGB";
+import finiteExtent from "../finiteExtent";
+
+/*
+create new colors state object.   Paramters:
+  - world - current world object
+  - mode - color-by mode.  One of: null, "color by expression",
+    "color by continuous metadata", "color by categorical metadata"
+  -
+*/
+function createColors(world, colorMode = null, colorAccessor = null) {
+  switch (colorMode) {
+    case "color by categorical metadata": {
+      return createColorsByCategoricalMetadata(world, colorAccessor);
+    }
+    case "color by continuous metadata": {
+      return createColorsByContinuousMetadata(world, colorAccessor);
+    }
+    case "color by expression": {
+      return createColorsByExpression(world, colorAccessor);
+    }
+    default: {
+      const defaultCellColor = parseRGB(globals.defaultCellColor);
+      return {
+        rgb: new Array(world.nObs).fill(defaultCellColor),
+        scale: undefined
+      };
+    }
+  }
+}
+
+function createColorsByCategoricalMetadata(world, accessor) {
+  const { categories } = _.filter(world.schema.annotations.obs, {
+    name: accessor
+  })[0];
+
+  const scale = d3
+    .scaleSequential(interpolateRainbow)
+    .domain([0, categories.length]);
+
+  /* pre-create colors - much faster than doing it for each obs */
+  const colors = categories.reduce((acc, cat, idx) => {
+    acc[cat] = parseRGB(scale(idx));
+    return acc;
+  }, {});
+
+  const rgb = new Array(world.nObs);
+  const data = world.obsAnnotations.col(accessor).asArray();
+  for (let i = 0, len = world.obsAnnotations.length; i < len; i += 1) {
+    const cat = data[i];
+    rgb[i] = colors[cat];
+  }
+  return { rgb, scale };
+}
+
+function createColorsByContinuousMetadata(world, accessor) {
+  const colorBins = 100;
+  const col = world.obsAnnotations.col(accessor);
+  const { min, max } = col.summarize();
+  const scale = d3
+    .scaleQuantile()
+    .domain([min, max])
+    .range(_.range(colorBins - 1, -1, -1));
+
+  /* pre-create colors - much faster than doing it for each obs */
+  const colors = new Array(colorBins);
+  for (let i = 0; i < colorBins; i += 1) {
+    colors[i] = parseRGB(interpolateCool(i / colorBins));
+  }
+
+  const nonFiniteColor = parseRGB(globals.nonFiniteCellColor);
+  const rgb = new Array(world.nObs);
+  const data = col.asArray();
+  for (let i = 0, len = world.obsAnnotations.length; i < len; i += 1) {
+    const val = data[i];
+    if (Number.isFinite(val)) {
+      const c = scale(val);
+      rgb[i] = colors[c];
+    } else {
+      rgb[i] = nonFiniteColor;
+    }
+  }
+  return { rgb, scale };
+}
+
+function createColorsByExpression(world, accessor) {
+  const expression = world.varData.col(accessor).asArray();
+  const colorBins = 100;
+  const [min, max] = finiteExtent(expression);
+  const scale = d3
+    .scaleQuantile()
+    .domain([min, max])
+    .range(_.range(colorBins - 1, -1, -1));
+
+  /* pre-create colors - much faster than doing it for each obs */
+  const colors = new Array(colorBins);
+  for (let i = 0; i < colorBins; i += 1) {
+    colors[i] = parseRGB(interpolateCool(i / colorBins));
+  }
+  const nonFiniteColor = parseRGB(globals.nonFiniteCellColor);
+
+  const rgb = new Array(world.nObs);
+  for (let i = 0, len = expression.length; i < len; i += 1) {
+    const e = expression[i];
+    if (Number.isFinite(e)) {
+      const c = scale(e);
+      rgb[i] = colors[c];
+    } else {
+      rgb[i] = nonFiniteColor;
+    }
+  }
+  return { rgb, scale };
+}
+
+export default createColors;

client/src/util/stateManager/index.js

@@ -14,7 +14,8 @@ This is all VERY tightly integrated with reducers and actions, and
 exists to support those concepts.
 */
 
+export { default as createColors } from "./colorHelpers";
 export * as Universe from "./universe";
 export * as World from "./world";
 export * as WorldUtil from "./worldUtil";
-export * as ControlsHelper from "./controlsHelpers";
+export * as ControlsHelpers from "./controlsHelpers";