fix: Allow non-linear scale for stacked bars (#9315)

Clone of #9311 by @richardliu-db to fix CI issues. See that PR for details. --------- Signed-off-by: Lukas Hermann <lukas.hermann@databricks.com> Co-authored-by: GitHub Actions Bot <vega-actions-bot@users.noreply.github.com>
vega · Apr 17, 2024 · 716fe73 · 716fe73
1 parent 8b3b30b
commit 716fe73
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Showing 4 changed files with 23 additions and 32 deletions.
diff --git a/examples/compiled/bar_q_qpow.vg.json b/examples/compiled/bar_q_qpow.vg.json
@@ -18,6 +18,14 @@
       "name": "data_0",
       "source": "source_0",
       "transform": [
+        {
+          "type": "stack",
+          "groupby": ["a"],
+          "field": "b",
+          "sort": {"field": [], "order": []},
+          "as": ["b_start", "b_end"],
+          "offset": "zero"
+        },
         {
           "type": "filter",
           "expr": "isValid(datum[\"a\"]) && isFinite(+datum[\"a\"]) && isValid(datum[\"b\"]) && isFinite(+datum[\"b\"])"
@@ -40,8 +48,8 @@
           },
           "xc": {"scale": "x", "field": "a"},
           "width": {"value": 5},
-          "y": {"scale": "y", "field": "b"},
-          "y2": {"scale": "y", "value": 0}
+          "y": {"scale": "y", "field": "b_end"},
+          "y2": {"scale": "y", "field": "b_start"}
         }
       }
     }
@@ -59,7 +67,7 @@
     {
       "name": "y",
       "type": "pow",
-      "domain": {"data": "data_0", "field": "b"},
+      "domain": {"data": "data_0", "fields": ["b_start", "b_end"]},
       "range": [{"signal": "height"}, 0],
       "nice": true,
       "zero": true

diff --git a/src/log/message.ts b/src/log/message.ts
@@ -344,8 +344,8 @@ export function cannotStackRangedMark(channel: Channel) {
   return `Cannot stack "${channel}" if there is already "${channel}2".`;
 }
 
-export function cannotStackNonLinearScale(scaleType: ScaleType) {
-  return `Cannot stack non-linear scale (${scaleType}).`;
+export function stackNonLinearScale(scaleType: ScaleType) {
+  return `Stack is applied to a non-linear scale (${scaleType}).`;
 }
 
 export function stackNonSummativeAggregate(aggregate: Aggregate | string) {

diff --git a/src/stack.ts b/src/stack.ts
@@ -245,9 +245,8 @@ export function stack(m: Mark | MarkDef, encoding: Encoding<string>): StackPrope
   // warn when stacking non-linear
   if (stackedFieldDef?.scale?.type && stackedFieldDef?.scale?.type !== ScaleType.LINEAR) {
     if (stackedFieldDef?.stack) {
-      log.warn(log.message.cannotStackNonLinearScale(stackedFieldDef.scale.type));
+      log.warn(log.message.stackNonLinearScale(stackedFieldDef.scale.type));
     }
-    return null;
   }
 
   // Check if it is a ranged mark

diff --git a/test/stack.test.ts b/test/stack.test.ts
@@ -256,9 +256,9 @@ describe('stack', () => {
   });
 
   it(
-    'should always warn if the aggregated axis has non-linear scale',
+    'should always return stack and only warn for non-undefined stack if the aggregated axis has non-linear scale',
     log.wrap(localLogger => {
-      for (const s of ['center', 'zero', 'normalize'] as const) {
+      for (const s of [undefined, 'center', 'zero', 'normalize'] as const) {
         for (const scaleType of [ScaleType.LOG, ScaleType.POW, ScaleType.SQRT]) {
           const marks = s === undefined ? STACK_BY_DEFAULT_NON_POLAR_MARKS : STACKABLE_NON_POLAR_MARKS;
           for (const mark of marks) {
@@ -271,36 +271,20 @@ describe('stack', () => {
                 color: {field: 'site', type: 'nominal'}
               }
             };
-            expect(stack(spec.mark, spec.encoding)).toBeNull();
-
+            expect(stack(spec.mark, spec.encoding)).toBeTruthy();
             const warns = localLogger.warns;
-            expect(warns[warns.length - 1]).toEqual(log.message.cannotStackNonLinearScale(scaleType));
+
+            if (s !== undefined) {
+              expect(warns[warns.length - 1]).toEqual(log.message.stackNonLinearScale(scaleType));
+            } else {
+              expect(warns).toHaveLength(0);
+            }
           }
         }
       }
     })
   );
 
-  it('returns null if the aggregated axis has non-linear scale', () => {
-    for (const stacked of [undefined, 'center', 'zero', 'normalize'] as const) {
-      for (const scaleType of [ScaleType.LOG, ScaleType.POW, ScaleType.SQRT]) {
-        const marks = stacked === undefined ? STACK_BY_DEFAULT_NON_POLAR_MARKS : STACKABLE_NON_POLAR_MARKS;
-        for (const mark of marks) {
-          const spec: TopLevel<NormalizedUnitSpec> = {
-            data: {url: 'data/barley.json'},
-            mark,
-            encoding: {
-              x: {field: 'a', type: 'quantitative', aggregate: 'sum', scale: {type: scaleType}},
-              y: {field: 'variety', type: 'nominal'},
-              color: {field: 'site', type: 'nominal'}
-            }
-          };
-          expect(stack(spec.mark, spec.encoding)).toBeNull();
-        }
-      }
-    }
-  });
-
   it(
     'should throw warning if the aggregated axis has a non-summative aggregate',
     log.wrap(localLogger => {