plotly · emilykl · Jun 16, 2026 · Jun 16, 2026 · Jun 16, 2026 · Jun 16, 2026
diff --git a/draftlogs/7843_change.md b/draftlogs/7843_change.md
@@ -0,0 +1 @@
+- Change `splom.axis.matches` default from `false` to `true` [[#7843](https://github.com/plotly/plotly.js/pull/7843)]
diff --git a/src/traces/splom/attributes.js b/src/traces/splom/attributes.js
@@ -90,10 +90,9 @@ module.exports = {
                 ].join(' ')
             },
 
-            // TODO make 'true' the default in v3?
             matches: {
                 valType: 'boolean',
-                dflt: false,
+                dflt: true,
                 editType: 'calc',
                 description: [
                     'Determines whether or not the x & y axes generated by this',

diff --git a/src/types/generated/schema.d.ts b/src/types/generated/schema.d.ts
@@ -10038,7 +10038,7 @@ export interface SplomData {
         axis?: {
             /**
              * Determines whether or not the x & y axes generated by this dimension match. Equivalent to setting the `matches` axis attribute in the layout with the correct axis id.
-             * @default false
+             * @default true
              */
             matches?: boolean;
             /** Sets the axis type for this dimension's generated x and y axes. Note that the axis `type` values set in layout take precedence over this attribute. */

diff --git a/test/image/baselines/splom_0.png b/test/image/baselines/splom_0.png
diff --git a/test/image/baselines/splom_array-styles.png b/test/image/baselines/splom_array-styles.png
diff --git a/test/image/baselines/splom_dates.png b/test/image/baselines/splom_dates.png
diff --git a/test/image/baselines/splom_iris.png b/test/image/baselines/splom_iris.png
diff --git a/test/image/baselines/splom_large.png b/test/image/baselines/splom_large.png
diff --git a/test/image/baselines/splom_log.png b/test/image/baselines/splom_log.png
diff --git a/test/image/baselines/splom_lower-nodiag.png b/test/image/baselines/splom_lower-nodiag.png
diff --git a/test/image/baselines/splom_lower.png b/test/image/baselines/splom_lower.png
diff --git a/test/image/baselines/splom_mismatched-axis-types.png b/test/image/baselines/splom_mismatched-axis-types.png
diff --git a/test/image/baselines/splom_multi-axis-type.png b/test/image/baselines/splom_multi-axis-type.png
diff --git a/test/image/baselines/splom_nodiag.png b/test/image/baselines/splom_nodiag.png
diff --git a/test/image/baselines/splom_ragged-via-axes.png b/test/image/baselines/splom_ragged-via-axes.png
diff --git a/test/image/baselines/splom_ragged-via-visible-false.png b/test/image/baselines/splom_ragged-via-visible-false.png
diff --git a/test/image/baselines/splom_symbol_numbers.png b/test/image/baselines/splom_symbol_numbers.png
diff --git a/test/image/baselines/splom_upper-nodiag.png b/test/image/baselines/splom_upper-nodiag.png
diff --git a/test/image/baselines/splom_upper.png b/test/image/baselines/splom_upper.png
diff --git a/test/image/baselines/splom_with-cartesian.png b/test/image/baselines/splom_with-cartesian.png
diff --git a/test/jasmine/tests/splom_test.js b/test/jasmine/tests/splom_test.js
@@ -695,26 +695,26 @@ describe('Test splom interactions:', function() {
         }
 
         _newPlot(gd, fig).then(function() {
-            _assert([1198, 16558, 3358, 118]);
+            _assert([1198, 16798, 3358, 118]);
             return Plotly.restyle(gd, 'showupperhalf', false);
         })
         .then(function() {
-            _assert([1198, 8476, 1768, 4]);
+            _assert([1198, 8704, 1768, 4]);
             return Plotly.restyle(gd, 'diagonal.visible', false);
         })
         .then(function() {
-            _assert([1138, 7534, 1600]);
+            _assert([1138, 7864, 1600]);
             return Plotly.restyle(gd, {
                 showupperhalf: true,
                 showlowerhalf: false
             });
         })
         .then(function() {
-            _assert([7966, 112, 1588]);
+            _assert([7978, 112, 1588]);
             return Plotly.restyle(gd, 'diagonal.visible', true);
         })
         .then(function() {
-            _assert([58, 8908, 1756, 118]);
+            _assert([58, 8932, 1756, 118]);
             return Plotly.relayout(gd, {
                 'xaxis.gridcolor': null,
                 'xaxis.gridwidth': null,
@@ -725,7 +725,7 @@ describe('Test splom interactions:', function() {
         .then(function() {
             // one batch for all 'grid' lines
             // and another for all 'zeroline' lines
-            _assert([8968, 1876]);
+            _assert([8992, 1876]);
         })
         .then(done, done.fail);
     });
@@ -1237,7 +1237,7 @@ describe('Test splom update switchboard:', function() {
 
             expect(scene.matrixOptions.size).toBe(20, msg);
             expect(gd._fullLayout.xaxis.range)
-                .toBeCloseToArray([0.753, 3.246], 1, 'xrng ' + msg);
+                .toBeCloseToArray([0.58, 3.42], 1, 'xrng ' + msg);
 
             return Plotly.restyle(gd, 'marker.size', [[4, 10, 20]]);
         })
@@ -1255,7 +1255,7 @@ describe('Test splom update switchboard:', function() {
 
             expect(scene.matrixOptions.sizes).toBeCloseToArray([4, 10, 20], 1, msg);
             expect(gd._fullLayout.xaxis.range)
-                .toBeCloseToArray([0.853, 3.235], 1, 'xrng ' + msg);
+                .toBeCloseToArray([0.81, 3.38], 1, 'xrng ' + msg);
 
             return Plotly.restyle(gd, 'marker.symbol', 'square');
         })
@@ -1484,11 +1484,11 @@ describe('Test splom drag:', function() {
             expect(scene.matrix.draw).toHaveBeenCalledTimes(3);
 
             _assertRanges('after drag', [
-                [2.9, 7.3],
+                [4.0, 8.5],
                 [1.7, 4.7],
                 [0.3, 7.6]
             ], [
-                [5.1, 9.6],
+                [4.0, 8.5],
                 [1.7, 4.7],
                 [0.3, 7.6]
             ]);

diff --git a/test/plot-schema.json b/test/plot-schema.json
@@ -75855,7 +75855,7 @@
                 "editType": "calc+clearAxisTypes",
                 "matches": {
                   "description": "Determines whether or not the x & y axes generated by this dimension match. Equivalent to setting the `matches` axis attribute in the layout with the correct axis id.",
-                  "dflt": false,
+                  "dflt": true,
                   "editType": "calc",
                   "valType": "boolean"
                 },
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		- Change `splom.axis.matches` default from `false` to `true` [[#7843](https://github.com/plotly/plotly.js/pull/7843)]