don’t stack with indexOf (#2179)

* test areaY shorthand with null & NaN

* don’t stack with indexOf

Author: mbostock

src/marks/area.js

@@ -78,10 +78,10 @@ export function area(data, options) {
 
 export function areaX(data, options) {
   const {y = indexOf, ...rest} = maybeDenseIntervalY(options);
-  return new Area(data, maybeStackX(maybeIdentityX({...rest, y1: y, y2: undefined})));
+  return new Area(data, maybeStackX(maybeIdentityX({...rest, y1: y, y2: undefined}, y === indexOf ? "x2" : "x")));
 }
 
 export function areaY(data, options) {
   const {x = indexOf, ...rest} = maybeDenseIntervalX(options);
-  return new Area(data, maybeStackY(maybeIdentityY({...rest, x1: x, x2: undefined})));
+  return new Area(data, maybeStackY(maybeIdentityY({...rest, x1: x, x2: undefined}, x === indexOf ? "y2" : "y")));
 }

src/transforms/identity.js

@@ -1,9 +1,9 @@
 import {hasX, hasY, identity} from "../options.js";
 
-export function maybeIdentityX(options = {}) {
-  return hasX(options) ? options : {...options, x: identity};
+export function maybeIdentityX(options = {}, k = "x") {
+  return hasX(options) ? options : {...options, [k]: identity};
 }
 
-export function maybeIdentityY(options = {}) {
-  return hasY(options) ? options : {...options, y: identity};
+export function maybeIdentityY(options = {}, k = "y") {
+  return hasY(options) ? options : {...options, [k]: identity};
 }

test/output/shorthandAreaYNaN.svg

@@ -8,3 +8,13 @@ export async function shorthandAreaY() {
   ];
   return Plot.areaY(numbers).plot();
 }
+
+export async function shorthandAreaYNaN() {
+  const numbers = [57.5, 37.6, 48.5, 42.4, NaN, NaN, NaN, NaN, 66.5, 67.7, 49.2, 58.7, 41.4, 54.4, 41.7, 49.8, 60.2, 44.5, 47.4, 33.5]; // prettier-ignore
+  return Plot.areaY(numbers).plot();
+}
+
+export async function shorthandAreaYNull() {
+  const numbers = [57.5, 37.6, 48.5, 42.4, null, null, null, null, 66.5, 67.7, 49.2, 58.7, 41.4, 54.4, 41.7, 49.8, 60.2, 44.5, 47.4, 33.5]; // prettier-ignore
+  return Plot.areaY(numbers).plot();
+}