Updated grid size heuristic to use statistical model

src/helpers/map.js

@@ -29,30 +29,36 @@ function dividers(a, b) {
   return factors(d);
 }
 
-const commonGridScales = [35, 70, 72, 111, 140, 144, 300];
+// The mean and standard deviation of > 1500 maps from the web
+const gridSizeMean = { x: 31.567792, y: 32.597987 };
+const gridSizeStd = { x: 14.438842, y: 15.582376 };
 
-// Most grid scales are above 10 and below 100
-function gridScaleVaild(x, y) {
+// Most grid sizes are above 10 and below 100
+function gridSizeVaild(x, y) {
   return x > 10 && y > 10 && x < 100 && y < 100;
 }
 
 export function gridSizeHeuristic(width, height) {
   const div = dividers(width, height);
   if (div.length > 0) {
-    let x = 1;
-    let y = 1;
-    // Check common scales but make sure the grid size is above 10 and below 100
-    for (let scale of commonGridScales) {
-      const tempX = Math.floor(width / scale);
-      const tempY = Math.floor(height / scale);
-      if (div.includes(scale) && gridScaleVaild(tempX, tempY)) {
-        x = tempX;
-        y = tempY;
+    // Find the best division by comparing the absolute z-scores of each axis
+    let bestX = 1;
+    let bestY = 1;
+    let bestScore = Number.MAX_VALUE;
+    for (let scale of div) {
+      const x = Math.floor(width / scale);
+      const y = Math.floor(height / scale);
+      const xScore = Math.abs((x - gridSizeMean.x) / gridSizeStd.x);
+      const yScore = Math.abs((y - gridSizeMean.y) / gridSizeStd.y);
+      if (xScore < bestScore || yScore < bestScore) {
+        bestX = x;
+        bestY = y;
+        bestScore = Math.min(xScore, yScore);
       }
     }
 
-    if (gridScaleVaild(x, y)) {
-      return { x, y };
+    if (gridSizeVaild(bestX, bestY)) {
+      return { x: bestX, y: bestY };
     }
   }
   return { x: 22, y: 22 };