Development/plot dist comparison warning

.gitignore

@@ -70,6 +70,9 @@ saved_animations/
 # mypy
 .mypy_cache
 
+# MacOS generated files
+.DS_Store
+
 # Stan file
 doc/getting_started/*.stan
 

arviz/plots/distcomparisonplot.py

@@ -1,9 +1,10 @@
 """Density Comparison plot."""
+import warnings
 from ..labels import BaseLabeller
 from ..rcparams import rcParams
 from ..utils import _var_names, get_coords
 from .plot_utils import get_plotting_function
-from ..sel_utils import xarray_var_iter
+from ..sel_utils import xarray_var_iter, xarray_sel_iter
 
 
 def plot_dist_comparison(
@@ -134,6 +135,19 @@ def plot_dist_comparison(
         for data, var in zip(datasets, var_names)
     ]
 
+    total_plots = sum(
+        1 for _ in xarray_sel_iter(datasets[0], var_names=var_names[0], combined=True)
+    )
+    maxplots = len(dc_plotters[0]) * (len(groups) + 1)
+
+    if total_plots > rcParams["plot.max_subplots"]:
+        warnings.warn(
+            "rcParams['plot.max_subplots'] ({max_plots}) is smaller than the number "
+            "of variables to plot ({len_plotters}), generating only {max_plots} "
+            "plots".format(max_plots=maxplots, len_plotters=total_plots),
+            UserWarning,
+        )
+
     nvars = len(dc_plotters[0])
     ngroups = len(groups)
 

arviz/tests/base_tests/test_plots_matplotlib.py

@@ -235,6 +235,13 @@ def test_plot_trace_max_subplots_warning(models):
     assert axes.shape == (3, 2)
 
 
+def test_plot_dist_comparison_warning(models):
+    with pytest.warns(UserWarning):
+        with rc_context(rc={"plot.max_subplots": 6}):
+            axes = plot_dist_comparison(models.model_1)
+    assert axes.shape == (2, 3)
+
+
 @pytest.mark.parametrize("kwargs", [{"var_names": ["mu", "tau"], "lines": [("hey", {}, [1])]}])
 def test_plot_trace_invalid_varname_warning(models, kwargs):
     with pytest.warns(UserWarning, match="valid var.+should be provided"):