include view definitions for a layercharts containing a repeat + toplevel selection parameter (#3031)

* add interactive crossfilter example as test

* include assert for test

* include spec to check instance

* blacken

* add new arguments

* change test for incremental views

Author: mattijn

altair/vegalite/v5/api.py

@@ -2661,8 +2661,8 @@ def __init__(
         _spec_as_list = [spec]
         params, _spec_as_list = _combine_subchart_params(params, _spec_as_list)
         spec = _spec_as_list[0]
-        if isinstance(spec, Chart):
-            params = _repeat_names(params, repeat)
+        if isinstance(spec, (Chart, LayerChart)):
+            params = _repeat_names(params, repeat, spec)
         super(RepeatChart, self).__init__(
             repeat=repeat,
             spec=spec,
@@ -3305,15 +3305,21 @@ def _get_repeat_strings(repeat):
     return ["".join(s) for s in itertools.product(*rcstrings)]
 
 
-def _extend_view_name(v, r):
+def _extend_view_name(v, r, spec):
     # prevent the same extension from happening more than once
-    if v.endswith("child__" + r):
-        return v
-    else:
-        return f"{v}_child__{r}"
+    if isinstance(spec, Chart):
+        if v.endswith("child__" + r):
+            return v
+        else:
+            return f"{v}_child__{r}"
+    elif isinstance(spec, LayerChart):
+        if v.startswith("child__" + r):
+            return v
+        else:
+            return f"child__{r}_{v}"
 
 
-def _repeat_names(params, repeat):
+def _repeat_names(params, repeat, spec):
     if params is Undefined:
         return params
 
@@ -3328,10 +3334,17 @@ def _repeat_names(params, repeat):
         views = []
         repeat_strings = _get_repeat_strings(repeat)
         for v in param.views:
-            if any(v.endswith(f"child__{r}") for r in repeat_strings):
-                views.append(v)
-            else:
-                views += [_extend_view_name(v, r) for r in repeat_strings]
+            if isinstance(spec, Chart):
+                if any(v.endswith(f"child__{r}") for r in repeat_strings):
+                    views.append(v)
+                else:
+                    views += [_extend_view_name(v, r, spec) for r in repeat_strings]
+            elif isinstance(spec, LayerChart):
+                if any(v.startswith(f"child__{r}") for r in repeat_strings):
+                    views.append(v)
+                else:
+                    views += [_extend_view_name(v, r, spec) for r in repeat_strings]
+
         p.views = views
         params_named.append(p)
 

tests/vegalite/v5/test_params.py

@@ -163,3 +163,36 @@ def test_selection_condition():
 
     # The else condition
     assert dct["encoding"]["size"]["value"] == 10
+
+
+def test_creation_views_params_layered_repeat_chart():
+    import altair as alt
+    from vega_datasets import data
+
+    source = alt.UrlData(data.flights_2k.url, format={"parse": {"date": "date"}})
+
+    brush = alt.selection_interval(encodings=["x"])
+
+    # Define the base chart, with the common parts of the
+    # background and highlights
+    base = (
+        alt.Chart(width=160, height=130)
+        .mark_bar()
+        .encode(x=alt.X(alt.repeat("column")).bin(maxbins=20), y="count()")
+    )
+
+    # gray background with selection
+    background = base.encode(color=alt.value("#ddd")).add_params(brush)
+
+    # blue highlights on the transformed data
+    highlight = base.transform_filter(brush)
+
+    # layer the two charts & repeat
+    c = (
+        alt.layer(background, highlight, data=source)
+        .transform_calculate("time", "hours(datum.date)")
+        .repeat(column=["distance", "delay", "time"])
+    )
+
+    dct = c.to_dict()
+    assert "child__column_distance_view_" in dct["params"][0]["views"][0]