Fix dimension ordering for traceplot with divergences (#2151)

* Transpose diverging to expected order

* Add test for correct behavior

* Use correct keyword argument

* Add new Changelog headers

* Add changelog entry

CHANGELOG.md

@@ -1,5 +1,16 @@
 # Change Log
 
+## v0.x.x Unreleased
+
+### New features
+
+### Maintenance and fixes
+- Fix dimension ordering for `plot_trace` with divergences ([2151](https://github.com/arviz-devs/arviz/pull/2151))
+
+### Deprecation
+
+### Documentation
+
 ## v0.13.0 (2022 Oct 22)
 
 ### New features

arviz/plots/traceplot.py

@@ -174,7 +174,9 @@ def plot_trace(
         divergences = "top" if rug else "bottom"
     if divergences:
         try:
-            divergence_data = convert_to_dataset(data, group="sample_stats").diverging
+            divergence_data = convert_to_dataset(data, group="sample_stats").diverging.transpose(
+                "chain", "draw"
+            )
         except (ValueError, AttributeError):  # No sample_stats, or no `.diverging`
             divergences = None
 

arviz/tests/base_tests/test_plots_matplotlib.py

@@ -294,6 +294,12 @@ def test_plot_trace_invalid_varname_warning(models, kwargs):
     assert axes.shape
 
 
+def test_plot_trace_diverging_correctly_transposed():
+    idata = load_arviz_data("centered_eight")
+    idata.sample_stats["diverging"] = idata.sample_stats.diverging.T
+    plot_trace(idata, divergences="bottom")
+
+
 @pytest.mark.parametrize(
     "bad_kwargs", [{"var_names": ["mu", "tau"], "lines": [("mu", {}, ["hey"])]}]
 )