From 06102aa21e624781a653f50cf8f38d965fbfe3e0 Mon Sep 17 00:00:00 2001 From: vinayak Date: Sun, 27 Sep 2026 16:18:06 +0530 Subject: [PATCH 1/3] Fix px scrambling categorical axis order when data is split into traces --- CHANGELOG.md | 1 + plotly/express/_core.py | 31 +++++++++++++++++++++++++ tests/test_optional/test_px/test_px.py | 32 ++++++++++++++++++++++++++ 3 files changed, 64 insertions(+) diff --git a/CHANGELOG.md b/CHANGELOG.md index c92c3ea6d64..ef14740f37d 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -17,6 +17,7 @@ This project adheres to [Semantic Versioning](http://semver.org/). - Fix Plotly Express mutating lists passed to the `x` or `y` arguments in wide mode [[#5727](https://github.com/plotly/plotly.py/pull/5727)], with thanks to @cpruijsen for the contribution! - Fix `px.sunburst`, `px.treemap` and `px.icicle` listing sectors in a different order on every run when `path` is used with a Polars DataFrame; sectors now follow their order of first appearance for all dataframe backends [[#5766](https://github.com/plotly/plotly.py/pull/5766)], with thanks to @Irahan2 for the contribution! - Fix `mpl_to_plotly` conversion of matplotlib contour lines and line collections: close contour rings ending with `Z` codes, support dash styles, convert date x-axes, separate disjoint subpaths with `None` separators, hide line collection traces from the legend by default, and group consecutive same-style lines into single traces [[#5770](https://github.com/plotly/plotly.py/pull/5770)], with thanks to @robertoffmoura for the contribution! +- Fix Plotly Express scrambling the order of categorical axes when the data is split into several traces (e.g. by `color`); the axis now follows the order of first appearance in the underlying data [[#3198](https://github.com/plotly/plotly.py/issues/3198), [#3291](https://github.com/plotly/plotly.py/issues/3291)] ## [7.1.0] - 2026-09-15 diff --git a/plotly/express/_core.py b/plotly/express/_core.py index 9994720b094..d51ab6b1cb0 100644 --- a/plotly/express/_core.py +++ b/plotly/express/_core.py @@ -2530,6 +2530,36 @@ def get_groups_and_orders(args, grouper): return groups, orders +def _default_category_orders_for_axes(args, groups, orders): + """ + Add data-appearance orders for categorical x/y columns. + + When the data is split into several traces (e.g. by `color`), plotly.js + orders categories by first appearance across traces, which can differ from + the order in the underlying data. Recording the data-appearance order here + lets `set_cartesian_axis_opts` emit an explicit `categoryarray`, matching + the documented behavior that Plotly Express lays out categorical data in + the order in which it appears in the data. See #3198. + """ + if len(groups) <= 1: + return orders + df = args["data_frame"] + for letter in ("x", "y"): + col = args.get(letter) + if not isinstance(col, str) or col in orders or col not in df.columns: + continue + uniques = df.get_column(col).unique(maintain_order=True).to_list() + categories = [ + value + for value in uniques + if value is not None + and not (isinstance(value, float) and math.isnan(value)) + ] + if categories and all(isinstance(value, str) for value in categories): + orders[col] = categories + return orders + + def make_figure(args, constructor, trace_patch=None, layout_patch=None): trace_patch = trace_patch or {} layout_patch = layout_patch or {} @@ -2556,6 +2586,7 @@ def make_figure(args, constructor, trace_patch=None, layout_patch=None): ) grouper = [x.grouper or one_group for x in grouped_mappings] or [one_group] groups, orders = get_groups_and_orders(args, grouper) + orders = _default_category_orders_for_axes(args, groups, orders) col_labels = [] row_labels = [] diff --git a/tests/test_optional/test_px/test_px.py b/tests/test_optional/test_px/test_px.py index d4773de66f8..4b9f8163c00 100644 --- a/tests/test_optional/test_px/test_px.py +++ b/tests/test_optional/test_px/test_px.py @@ -361,6 +361,38 @@ def test_category_order_with_category_as_x(backend): assert set(trace["x"]) == {"Thur", "Fri", "Sat", "Sun"} +def test_category_order_defaults_to_data_order_with_color(): + # https://github.com/plotly/plotly.py/issues/3198 + # Splitting into one trace per color must not change the axis order: + # it should follow first appearance in the underlying data. + fig = px.line( + x=["A", "B", None, "B", "C", None, "C", "D", None, "D", "E", None], + y=[1, 1, None, 2, 2, None, 3, 3, None, 4, 4, None], + color=[1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 1], + ) + assert fig["layout"]["xaxis"]["categoryorder"] == "array" + assert fig["layout"]["xaxis"]["categoryarray"] == ("A", "B", "C", "D", "E") + + +def test_category_order_defaults_to_data_order_with_color_bar(): + # https://github.com/plotly/plotly.py/issues/3291 + df = pd.DataFrame( + {"x": ["a", "b", "c", "d"], "y": [1, 2, 3, 4], "z": ["p", "q", "p", "q"]} + ) + fig = px.bar(df, x="x", y="y", color="z") + assert fig["layout"]["xaxis"]["categoryorder"] == "array" + assert fig["layout"]["xaxis"]["categoryarray"] == ("a", "b", "c", "d") + + +def test_no_default_category_array_for_single_trace_or_numeric(): + # A single trace already follows data order, and numeric axes + # must never get a category array. + fig = px.line(x=["A", "B", "C"], y=[1, 2, 3]) + assert fig["layout"]["xaxis"]["categoryorder"] is None + fig = px.line(x=[1, 2, 3], y=[1, 2, 3], color=["a", "b", "a"]) + assert fig["layout"]["xaxis"]["categoryorder"] is None + + def test_permissive_defaults(): msg = "'PxDefaults' object has no attribute 'should_not_work'" with pytest.raises(AttributeError, match=msg): From 16ab376c917c63ebdcd8a6416fcc74ade6ccb276 Mon Sep 17 00:00:00 2001 From: vinayak Date: Sat, 10 Oct 2026 17:48:48 +0530 Subject: [PATCH 2/3] Scope default category order to x-axis only Address review on #5776: y categoricals stay untouched so the autorange=reversed pattern from doc/python/gantt.md keeps listing tasks top-down instead of double-reversing. Adds guard test that px.timeline and horizontal px.bar with color emit no y categoryarray, while x data-order fix for #3198/#3291 is kept. --- CHANGELOG.md | 4 +++- plotly/express/_core.py | 33 +++++++++++++++----------- tests/test_optional/test_px/test_px.py | 19 +++++++++++++++ 3 files changed, 41 insertions(+), 15 deletions(-) diff --git a/CHANGELOG.md b/CHANGELOG.md index ef14740f37d..ef2079656f8 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -17,7 +17,9 @@ This project adheres to [Semantic Versioning](http://semver.org/). - Fix Plotly Express mutating lists passed to the `x` or `y` arguments in wide mode [[#5727](https://github.com/plotly/plotly.py/pull/5727)], with thanks to @cpruijsen for the contribution! - Fix `px.sunburst`, `px.treemap` and `px.icicle` listing sectors in a different order on every run when `path` is used with a Polars DataFrame; sectors now follow their order of first appearance for all dataframe backends [[#5766](https://github.com/plotly/plotly.py/pull/5766)], with thanks to @Irahan2 for the contribution! - Fix `mpl_to_plotly` conversion of matplotlib contour lines and line collections: close contour rings ending with `Z` codes, support dash styles, convert date x-axes, separate disjoint subpaths with `None` separators, hide line collection traces from the legend by default, and group consecutive same-style lines into single traces [[#5770](https://github.com/plotly/plotly.py/pull/5770)], with thanks to @robertoffmoura for the contribution! -- Fix Plotly Express scrambling the order of categorical axes when the data is split into several traces (e.g. by `color`); the axis now follows the order of first appearance in the underlying data [[#3198](https://github.com/plotly/plotly.py/issues/3198), [#3291](https://github.com/plotly/plotly.py/issues/3291)] +- Fix Plotly Express scrambling the order of the categorical x-axis when the data is split into several traces (e.g. by `color`); the x-axis now follows the order of first appearance in the underlying data [[#3198](https://github.com/plotly/plotly.py/issues/3198), [#3291](https://github.com/plotly/plotly.py/issues/3291)] + +## [7.1.0] - 2026-09-15 ## [7.1.0] - 2026-09-15 diff --git a/plotly/express/_core.py b/plotly/express/_core.py index d51ab6b1cb0..5800ede4ac2 100644 --- a/plotly/express/_core.py +++ b/plotly/express/_core.py @@ -2532,7 +2532,7 @@ def get_groups_and_orders(args, grouper): def _default_category_orders_for_axes(args, groups, orders): """ - Add data-appearance orders for categorical x/y columns. + Add data-appearance order for the categorical x column. When the data is split into several traces (e.g. by `color`), plotly.js orders categories by first appearance across traces, which can differ from @@ -2540,23 +2540,28 @@ def _default_category_orders_for_axes(args, groups, orders): lets `set_cartesian_axis_opts` emit an explicit `categoryarray`, matching the documented behavior that Plotly Express lays out categorical data in the order in which it appears in the data. See #3198. + + Only the x axis is handled: y categoricals are intentionally left alone + because `set_cartesian_axis_opts` reverses y orders for top-down display + and figures such as `px.timeline` / horizontal `px.bar` pair that with + `autorange="reversed"` (see `doc/python/gantt.md`), so an explicit y + `categoryarray` would double-reverse and flip the documented order. """ if len(groups) <= 1: return orders df = args["data_frame"] - for letter in ("x", "y"): - col = args.get(letter) - if not isinstance(col, str) or col in orders or col not in df.columns: - continue - uniques = df.get_column(col).unique(maintain_order=True).to_list() - categories = [ - value - for value in uniques - if value is not None - and not (isinstance(value, float) and math.isnan(value)) - ] - if categories and all(isinstance(value, str) for value in categories): - orders[col] = categories + col = args.get("x") + if not isinstance(col, str) or col in orders or col not in df.columns: + return orders + uniques = df.get_column(col).unique(maintain_order=True).to_list() + categories = [ + value + for value in uniques + if value is not None + and not (isinstance(value, float) and math.isnan(value)) + ] + if categories and all(isinstance(value, str) for value in categories): + orders[col] = categories return orders diff --git a/tests/test_optional/test_px/test_px.py b/tests/test_optional/test_px/test_px.py index 4b9f8163c00..104ac447495 100644 --- a/tests/test_optional/test_px/test_px.py +++ b/tests/test_optional/test_px/test_px.py @@ -393,6 +393,25 @@ def test_no_default_category_array_for_single_trace_or_numeric(): assert fig["layout"]["xaxis"]["categoryorder"] is None +def test_no_default_category_array_for_y_with_color(): + # https://github.com/plotly/plotly.py/pull/5776#pullrequestreview-5478271667 + # y categoricals must stay untouched so the `autorange="reversed"` + # pattern from doc/python/gantt.md keeps listing tasks top-down. + df = pd.DataFrame( + [ + dict(Task="Job A", Start="2009-01-01", Finish="2009-02-28", Resource="Alex"), + dict(Task="Job B", Start="2009-03-05", Finish="2009-04-15", Resource="Alex"), + dict(Task="Job C", Start="2009-02-20", Finish="2009-05-30", Resource="Max"), + ] + ) + fig = px.timeline(df, x_start="Start", x_end="Finish", y="Task", color="Resource") + assert fig["layout"]["yaxis"]["categoryorder"] is None + assert fig["layout"]["yaxis"]["categoryarray"] is None + fig = px.bar(x=[1, 2, 3, 4], y=list("abcd"), color=list("ppqq"), orientation="h") + assert fig["layout"]["yaxis"]["categoryorder"] is None + assert fig["layout"]["yaxis"]["categoryarray"] is None + + def test_permissive_defaults(): msg = "'PxDefaults' object has no attribute 'should_not_work'" with pytest.raises(AttributeError, match=msg): From 55d5c75efb23557eaa6eb61619706c589727648d Mon Sep 17 00:00:00 2001 From: vinayak Date: Mon, 12 Oct 2026 16:47:32 +0530 Subject: [PATCH 3/3] Remove duplicated 7.1.0 heading in CHANGELOG --- CHANGELOG.md | 2 -- 1 file changed, 2 deletions(-) diff --git a/CHANGELOG.md b/CHANGELOG.md index ef2079656f8..7e3ecbc81a3 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -21,8 +21,6 @@ This project adheres to [Semantic Versioning](http://semver.org/). ## [7.1.0] - 2026-09-15 -## [7.1.0] - 2026-09-15 - ### Added - Support `marginal_x`/`marginal_y="heatmap"` in `density_heatmap`, drawing a single-row/column heatmap strip in the margin colored by the same `z`/`histfunc` aggregate as the main plot and sharing its color scale [[#5706](https://github.com/plotly/plotly.py/issues/5706)], with thanks to @lucasjamar for the contribution! - Add support for custom tick values in `mpl_to_plotly` when the matplotlib tick positions don't follow an arithmetic progression, including custom tick labels and tick values on date axes [[#5262](https://github.com/plotly/plotly.py/pull/5262)], with thanks to @robertoffmoura for the contribution!