single paths for undefined data

Author: mbostock

src/marks/area.js

@@ -42,6 +42,7 @@ export class Area extends Mark {
             .call(applyDirectStyles, this)
             .call(applyGroupedChannelStyles, this, channels)
             .attr("d", shapeArea()
+              .defined(i => i >= 0)
               .curve(this.curve)
               .x0(i => X1[i])
               .y0(i => Y1[i])

src/marks/line.js

@@ -43,6 +43,7 @@ export class Line extends Mark {
             .call(applyGroupedChannelStyles, this, channels)
             .call(applyGroupedMarkers, this, channels)
             .attr("d", shapeLine()
+              .defined(i => i >= 0)
               .curve(this.curve)
               .x(i => X[i])
               .y(i => Y[i])))

src/style.js

@@ -191,12 +191,10 @@ export function* groupIndex(I, position, channels) {
     let Gg; // the current group index (a subset of G, and I), if any
     out: for (const i of G) {
 
-      // If any channel has an undefined value for this index, yield the current
-      // group and start a new empty group, skipping this index.
+      // If any channel has an undefined value for this index, skip it.
       for (const c of C) {
         if (!defined(c[i])) {
-          if (Gg) yield Gg;
-          Ag = Gg = undefined;
+          if (Gg) Gg.push(-1);
           continue out;
         }
       }