trivial intervals for rect (#831)

Author: mbostock

src/marks/rect.js

@@ -4,7 +4,7 @@ import {Mark} from "../plot.js";
 import {isCollapsed} from "../scales.js";
 import {applyDirectStyles, applyIndirectStyles, applyTransform, impliedString, applyAttr, applyChannelStyles} from "../style.js";
 import {maybeIdentityX, maybeIdentityY} from "../transforms/identity.js";
-import {maybeIntervalX, maybeIntervalY} from "../transforms/interval.js";
+import {maybeTrivialIntervalX, maybeTrivialIntervalY} from "../transforms/interval.js";
 import {maybeStackX, maybeStackY} from "../transforms/stack.js";
 
 const defaults = {
@@ -68,13 +68,13 @@ export class Rect extends Mark {
 }
 
 export function rect(data, options) {
-  return new Rect(data, maybeIntervalX(maybeIntervalY(options)));
+  return new Rect(data, maybeTrivialIntervalX(maybeTrivialIntervalY(options)));
 }
 
 export function rectX(data, options = {y: indexOf, interval: 1, x2: identity}) {
-  return new Rect(data, maybeStackX(maybeIntervalY(maybeIdentityX(options))));
+  return new Rect(data, maybeStackX(maybeTrivialIntervalY(maybeIdentityX(options))));
 }
 
 export function rectY(data, options = {x: indexOf, interval: 1, y2: identity}) {
-  return new Rect(data, maybeStackY(maybeIntervalX(maybeIdentityY(options))));
+  return new Rect(data, maybeStackY(maybeTrivialIntervalX(maybeIdentityY(options))));
 }

src/transforms/interval.js

@@ -28,21 +28,39 @@ function maybeIntervalValue(value, {interval}) {
   return value;
 }
 
-function maybeIntervalK(k, maybeInsetK, options) {
+function maybeIntervalK(k, maybeInsetK, options, trivial) {
   const {[k]: v, [`${k}1`]: v1, [`${k}2`]: v2} = options;
   const {value, interval} = maybeIntervalValue(v, options);
-  if (value == null || interval == null) return options;
+  if (value == null || (interval == null && !trivial)) return options;
+  const label = labelof(v);
+  if (interval == null) {
+    let V;
+    const kv = {transform: data => V || (V = valueof(data, value)), label};
+    return {
+      ...options,
+      [k]: undefined,
+      [`${k}1`]: v1 === undefined ? kv : v1,
+      [`${k}2`]: v2 === undefined ? kv : v2
+    };
+  }
   let V1;
   const tv1 = data => V1 || (V1 = valueof(data, value).map(v => interval.floor(v)));
-  const label = labelof(v);
   return maybeInsetK({
     ...options,
     [k]: undefined,
     [`${k}1`]: v1 === undefined ? {transform: tv1, label} : v1,
-    [`${k}2`]: v2 === undefined ? {transform: () => tv1().map(v => interval.offset(v)), label} : v2
+    [`${k}2`]: v2 === undefined ? {transform: data => tv1(data).map(v => interval.offset(v)), label} : v2
   });
 }
 
+export function maybeTrivialIntervalX(options = {}) {
+  return maybeIntervalK("x", maybeInsetX, options, true);
+}
+
+export function maybeTrivialIntervalY(options = {}) {
+  return maybeIntervalK("y", maybeInsetY, options, true);
+}
+
 export function maybeIntervalX(options = {}) {
   return maybeIntervalK("x", maybeInsetX, options);
 }

test/output/groupedRects.svg

@@ -0,0 +1,9 @@
+import * as Plot from "@observablehq/plot";
+
+export default async function() {
+  return Plot.plot({
+    marks: [
+      Plot.rectY({length: 10}, Plot.groupX({y: "count"}, {x: (d, i) => "ABCDEFGHIJ"[i]}))
+    ]
+  });
+}

test/plots/grouped-rects.js

@@ -61,6 +61,7 @@ export {default as gistempAnomalyMoving} from "./gistemp-anomaly-moving.js";
 export {default as gistempAnomalyTransform} from "./gistemp-anomaly-transform.js";
 export {default as googleTrendsRidgeline} from "./google-trends-ridgeline.js";
 export {default as gridChoropleth} from "./grid-choropleth.js";
+export {default as groupedRects} from "./grouped-rects.js";
 export {default as hadcrutWarmingStripes} from "./hadcrut-warming-stripes.js";
 export {default as highCardinalityOrdinal} from "./high-cardinality-ordinal.js";
 export {default as identityScale} from "./identity-scale.js";