Pie legend and showlegend per slice #7580

my-tien · 2025-10-13T08:24:52Z

This PR makes it possible to pass arrays to the pie properties 'legend' and 'showlegend' so that legend assignment and visibility can be configured per slice.

Changes:

Previously, traces.pie.legend and traces.pie.showlegend only accepted one value that applied for all slices. With this PR, slice legend entries can be grouped and individual slices can be hidden in the legend:

{
 "data": [
  {
   "labels": [
     "BBBBBBBBBBBBBBBBBB",
     "AAAAAAAAAAAAAAAAAA",
     "222222222222222222",
     "111111111111111111",
     "unimportant"
    ],
   "values": [10, 15, 13, 19, 1],
   "type": "pie",
   "showlegend": [true, true, true, true, false],
   "legend": ["legend", "legend", "legend2", "legend2"]
  }
 ],
 "layout": {
  "width": 400,
  "height": 400,
  "legend": {
    "title": {
        "text": "Group 1"
    },
    "xanchor": "left",
    "yanchor": "top",
    "x": -0.2,
    "y": -0.1
  },
  "legend2": {
    "title": {
        "text": "Group 2"
    },
    "xanchor": "left",
    "yanchor": "top",
    "x": 0.6,
    "y": -0.1
  }
 }
}

Result

Old behavior

No possibility to group slices semantically or to hide a slice. Also takes up more vertical space.

Testing

For testing, I added 3 mocks:

zz-pie-slice-legend.json verifies that the array entries are associated to the pie slices in declaration order.
zz-pie-slice-legend2.json verifies that if the arrays have less entries than there are pie slices, the extra slices are assigned default values.
zz-pie-slice-legend3.json verifies that the arrays also work when label0 and dlabel are set instead of labels.

Note:

This feature is not expected to work when pie values are not set.

Disclaimer

I am required to add that…

the software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. in no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

…ice legend visibility.

…legend assignment.

…pies with showlegend and/or legend as arrays

my-tien · 2025-11-12T10:55:35Z

@alexshoe Hi Alex! Do you possibly have an estimate when this PR could be tackled? Also, let me know if you have any questions :)

alexshoe · 2025-11-12T21:24:31Z

Hey @my-tien! Sorry, just working through a backlog of different PRs that I was assigned. I'll start reviewing this tomorrow.

…isibility # Conflicts: # test/plot-schema.json

my-tien · 2025-11-25T11:43:12Z

@alexshoe Hi Alex, I saw that my branch got out of date and conflicted with the current test/plot-schema.json .
I merged master into my branch, reran npm run schema and saw below output. Is this output currently expected and does it still generate a correct plot-schema.json since the last statement is still »ok plot-schema.json« (I installed dependencies via npm run i -d and I have canvas in my node_modules folder)?

EDIT: After wiping node_modules and re-installing with npm i the errors went away.

plotly.js@3.3.0 schema
node tasks/schema.mjs

build\plotly.js 11.0mb

Done in 7872ms
Error: Not implemented: HTMLCanvasElement.prototype.getContext (without installing the canvas npm package)
at module.exports (...\plotly.js\node_modules\jsdom\lib\jsdom\browser\not-implemented.js:9:17)
at HTMLCanvasElementImpl.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\nodes\HTMLCanvasElement-impl.js:42:5)
at HTMLCanvasElement.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\generated\HTMLCanvasElement.js:131:58)
at 4359 (about:blank:106137:48)
at __webpack_require__ (about:blank:128019:41)
at 4935 (about:blank:108491:35)
at __webpack_require__ (about:blank:128019:41)
at 3837 (about:blank:103258:32)
at __webpack_require__ (about:blank:128019:41)
at 4100 (about:blank:104906:32) undefined
Error: Not implemented: HTMLCanvasElement.prototype.getContext (without installing the canvas npm package)
at module.exports (...\plotly.js\node_modules\jsdom\lib\jsdom\browser\not-implemented.js:9:17)
at HTMLCanvasElementImpl.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\nodes\HTMLCanvasElement-impl.js:42:5)
at HTMLCanvasElement.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\generated\HTMLCanvasElement.js:131:58)
at node_modules/svg-path-sdf/index.js (about:blank:148569:24)
at __require (about:blank:42:52)
at src/traces/scattergl/convert.js (about:blank:148638:20)
at __require (about:blank:42:52)
at src/traces/scattergl/calc.js (about:blank:149375:21)
at __require (about:blank:42:52)
at src/traces/scattergl/base_index.js (about:blank:149636:15) undefined
Error: Not implemented: HTMLCanvasElement.prototype.getContext (without installing the canvas npm package)
at module.exports (...\plotly.js\node_modules\jsdom\lib\jsdom\browser\not-implemented.js:9:17)
at HTMLCanvasElementImpl.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\nodes\HTMLCanvasElement-impl.js:42:5)
at HTMLCanvasElement.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\generated\HTMLCanvasElement.js:131:58)
at node_modules/detect-kerning/index.js (about:blank:163622:24)
at __require (about:blank:42:52)
at node_modules/gl-text/dist.js (about:blank:163834:21)
at __require (about:blank:42:52)
at src/traces/scattergl/plot.js (about:blank:172852:18)
at __require (about:blank:42:52)
at src/traces/scattergl/index.js (about:blank:173168:20) undefined
Error: Not implemented: HTMLCanvasElement.prototype.getContext (without installing the canvas npm package)
at module.exports (...\plotly.js\node_modules\jsdom\lib\jsdom\browser\not-implemented.js:9:17)
at HTMLCanvasElementImpl.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\nodes\HTMLCanvasElement-impl.js:42:5)
at HTMLCanvasElement.getContext (...\plotly.js\node_modules\jsdom\lib\jsdom\living\generated\HTMLCanvasElement.js:131:58)
at node_modules/gl-text/dist.js (about:blank:164409:48)
at __require (about:blank:42:52)
at src/traces/scattergl/plot.js (about:blank:172852:18)
at __require (about:blank:42:52)
at src/traces/scattergl/index.js (about:blank:173168:20)
at __require (about:blank:42:52)
at lib/scattergl.js (about:blank:173177:24) undefined
ok plot-schema.json

camdecoster · 2025-11-25T20:10:58Z

@my-tien could you please add some more information to the OP? I'm interested in seeing sections describing:

Changes
Before/after pictures or videos
Testing instructions

With that, I'll be able to better review the changes.

… is provided.

…d instead of labels.

my-tien · 2025-11-26T12:43:59Z

Hi @camdecoster,
Thx for looking at my PR! Regarding my error above, this was resolved by completely deleting my node_modules and re-installing again.

I also updated the OP and added a better description of the properties for the plot schema. Please let me know if anything is unclear or missing!

camdecoster

Thanks for adding this feature! There are a few changes to make, but it seems to work well.

src/components/legend/defaults.js

camdecoster · 2025-11-26T19:30:09Z

src/components/legend/defaults.js

+                        !Array.isArray(trace.showlegend)
+                        ? trace.showlegend || trace._dfltShowLegend
+                        : trace.showlegend[index] == null
+                        ? trace._dfltShowLegend
+                        : trace.showlegend[index]


Could you please refactor this to avoid nested ternary expressions?

Hope it's clearer now! Leaving the conversation unresolved for your judgement :)

src/components/legend/defaults.js

test/image/mocks/zz-pie-slice-legend.json

test/image/mocks/zz-pie-slice-legend3.json

src/lib/coerce.js

test/image/mocks/zz-pie-slice-legend2.json

test/image/mocks/zz-pie-slice-legend.json

….legend is an array

figure width was changed.

camdecoster

Here are a few more suggestions.

camdecoster · 2025-11-28T22:17:16Z

src/components/legend/defaults.js

+                    var showInLegend = trace.showlegend || trace._dfltShowLegend;
+                    if (Array.isArray(trace.showlegend)) {
+                        showInLegend = trace.showlegend[index] ?? trace._dfltShowLegend;
+                    }
+                    if(showInLegend) {
+                        legendReallyHasATrace = true;
+                        legendTraceCount++;
+                    }


What about something like this? I'm not sure if you really need the nullish coalescing operator. If you do, then this will need to be adjusted.

Suggested change

var showInLegend = trace.showlegend || trace._dfltShowLegend;

if (Array.isArray(trace.showlegend)) {

showInLegend = trace.showlegend[index] ?? trace._dfltShowLegend;

}

if(showInLegend) {

legendReallyHasATrace = true;

legendTraceCount++;

}

const showInLegend = Array.isArray(trace.showlegend) ? trace.showlegend[index] : trace.showlegend;

if (showInLegend || trace._dfltShowLegend) {

legendReallyHasATrace = true;

legendTraceCount++;

}

camdecoster · 2025-11-28T22:34:26Z

src/lib/coerce.js

+            function isBoolean(value) {
+                return value === true || value === false;
+            }


Let's make this a one-liner:

Suggested change

function isBoolean(value) {

return value === true || value === false;

}

const isBoolean = value => value === true || value === false;

Or

Suggested change

function isBoolean(value) {

return value === true || value === false;

}

const isBoolean = value => typeof value === "boolean";

camdecoster · 2025-11-28T22:35:15Z

src/lib/coerce.js

+                return value === true || value === false;
+            }
+
+            if (opts.arrayOk && isArrayOrTypedArray(v) && v.length > 0 && v.every(isBoolean)) {


Do you anticipate typed arrays being used here?

camdecoster · 2025-11-28T22:38:11Z

src/lib/coerce.js

+            if (opts.arrayOk && isArrayOrTypedArray(v) && v.length > 0 && v.every(isBoolean)) {
+                propOut.set(v);
+            } else if(isBoolean(v)) {
+                propOut.set(v);


Could you combine these two paths since they result in the same call?

camdecoster · 2025-12-01T16:33:45Z

src/lib/coerce.js

+            function isSubplotId(value) {
+                return typeof value === 'string' && regex.test(value);
+            }


Suggested change

function isSubplotId(value) {

return typeof value === 'string' && regex.test(value);

}

const isSubplotId = value => typeof value === 'string' && regex.test(value);

camdecoster · 2025-12-01T16:34:05Z

src/lib/coerce.js

+            if (opts.arrayOk && isArrayOrTypedArray(v) && v.length > 0 && v.every(isSubplotId)) {
                propOut.set(v);
-                return;
+            } else if(isSubplotId(v)) {
+                propOut.set(v);


Could you combine these two paths since they result in the same call?

my-tien added 9 commits October 13, 2025 09:14

Make pie.showlegend accept a boolean array to configure individual sl…

4fc0e3b

…ice legend visibility.

Make pie.legend accept a boolean array to configure individual slice …

417ca2e

…legend assignment.

Mocks for testing pie.legend and pie.showlegend arrays.

449598d

Add draftlog for plotly#7580

178959e

Add missing plot-schema change

3f9143d

Baselines for tests zz-pie-slice-legend and zz-pie-slice-legend2

f9c65da

Fix defaults for legend when pie has no slices.

09bcc61

Change pie influence on default legend visibility only for non-empty …

dd73d5a

…pies with showlegend and/or legend as arrays

debugger statement…

71c01fb

alexshoe self-assigned this Oct 14, 2025

gvwilson added feature something new community community contribution P1 needed for current cycle labels Oct 28, 2025

Merge remote-tracking branch 'origin-plotly/master' into pie-legend-v…

177dca3

…isibility # Conflicts: # test/plot-schema.json

robertclaus assigned camdecoster and unassigned alexshoe Nov 25, 2025

robertclaus requested a review from camdecoster November 25, 2025 19:25

my-tien added 2 commits November 26, 2025 13:34

Clarify that pie legend and showlegend can only be arrays if values…

3e5e53f

… is provided.

Add baseline test for pie legend/showlegend arrays when label0 is use…

ab11db2

…d instead of labels.

baseline image for zz-pie-slice-legend3.png

73c531e

camdecoster requested changes Nov 26, 2025

View reviewed changes

my-tien added 4 commits November 27, 2025 14:28

Fix indentation in zz-pie-slice-legend mocks

8f983db

Enhance readability in legend groupdefaults

a115e4e

Fix default legend's groupdefaults calculation being skipped when pie…

ef93f2c

….legend is an array

coerce.js boolean and subplotid: Actually do checks on array values.

7ec5316

my-tien requested a review from camdecoster November 27, 2025 13:36

my-tien added 3 commits November 27, 2025 17:22

Fix missing opts param in boolean coerceFunction

795b911

Revert accidental change in zz-pie-slice-legend3 mock

a73c4f9

Replace baseline images for zz-pie-slice[2].png

2636c7b

figure width was changed.

camdecoster reviewed Dec 1, 2025

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Changes:

Result

Old behavior

Testing

Note:

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