filter out property if not set

ultraplot/constructor.py

@@ -881,10 +881,10 @@ def _parse_basic_properties(self, kwargs):
 
     def _handle_empty_args(self, props, kwargs):
         """Handle case when no positional arguments are provided."""
-        props.setdefault("color", "black")
+        props.setdefault("color", ["black"])
         if kwargs:
             warnings._warn_ultraplot(f"Ignoring Cycle() keyword arg(s) {kwargs}.")
-        self._build_cycler(())
+        self._build_cycler((props,))
 
     def _handle_cycler_args(self, args, props, kwargs):
         """Handle case when arguments are cycler objects."""
@@ -928,13 +928,17 @@ def _build_cycler(self, dicts):
                 props.setdefault(key, []).extend(value)
         # Build cycler with matching property lengths
         # Ensure at least a default color property exists
-        if not props:
-            props = {"color": ["black"]}
-
         # Build cycler with matching property lengths
         lengths = [len(value) for value in props.values()]
         maxlen = np.lcm.reduce(lengths)
-        props = {key: value * (maxlen // len(value)) for key, value in props.items()}
+        props = {
+            key: value * (maxlen // len(value))
+            for key, value in props.items()
+            if len(value)
+        }
+        # Set default color property if not present
+        if "color" not in props or not props:
+            props = {"color": ["black"]}
         mcycler = cycler.cycler(**props)
         super().__init__(mcycler)
 

ultraplot/tests/test_constructor.py

@@ -65,6 +65,10 @@ def test_not_allowed_keyword():
 def test_cycler_edge_cases():
     """Test edge cases and error conditions"""
     # Test with empty lists
+    cycle = uplt.Cycle()
+    assert cycle.get_next() == dict(color="black")  # default fallback
+    cycle = uplt.Cycle(color=[])
+    assert cycle.get_next() == dict(color="black")  # default fallback
     cycle = uplt.Cycle(colors=[])
     assert cycle.get_next() == dict(color="black")  # default fallback
 
@@ -74,6 +78,7 @@ def test_cycler_edge_cases():
     props1 = cycle.get_next()
     props2 = cycle.get_next()
     assert props1["marker"] == props2["marker"]  # marker should stay same
+    assert props1["color"] == "red"
     assert props1["color"] != props2["color"]  # color should cycle
 
 
@@ -108,3 +113,12 @@ def test_pass_on_cycle():
     for color in colors:
         assert color == active_cycle.get_next()["color"]
         assert color == cycle.get_next()["color"]
+
+    colors = ["red", "green", "black"]
+    cycle = uplt.Cycle(color=colors)
+    fig, ax = uplt.subplots()
+    ax.set_prop_cycle(cycle)
+    active_cycle = ax.axes._active_cycle
+    for color in colors:
+        assert color == active_cycle.get_next()["color"]
+        assert color == cycle.get_next()["color"]