Fix/norm inputs

ultraplot/axes/plot.py

@@ -4120,9 +4120,30 @@ def _parse_cmap(
         # Parse keyword args
         cmap_kw = cmap_kw or {}
         norm_kw = norm_kw or {}
-        # If norm is given we use it to set vmin and vmax
-        if (vmin is not None or vmax is not None) and norm is not None:
-            raise ValueError("If 'norm' is given, 'vmin' and 'vmax' must not be set.")
+        # Tuple/list specs like ``('linear', 0, 1)`` pack positional args for
+        # ``constructor.Norm``. Build the Normalize now so downstream code can
+        # treat it uniformly with pre-constructed Normalize instances instead
+        # of risking a positional/kwarg collision when vmin/vmax are forwarded.
+        if (
+            np.iterable(norm)
+            and not isinstance(norm, str)
+            and not isinstance(norm, mcolors.Normalize)
+            and len(norm) > 1
+        ):
+            norm = constructor.Norm(norm, **norm_kw)
+            norm_kw = {}
+        # A ``Normalize`` instance already carries vmin/vmax, so combining it
+        # with explicit vmin/vmax is ambiguous. String / single-element list or
+        # tuple specs are just names for ``constructor.Norm`` and accept
+        # vmin/vmax as kwargs.
+        if (vmin is not None or vmax is not None) and isinstance(
+            norm, mcolors.Normalize
+        ):
+            raise ValueError(
+                "If 'norm' is a Normalize instance, 'vmin' and 'vmax' must not be "
+                "set. Pass them through the Normalize constructor, or specify "
+                "'norm' as a string / list / tuple to let vmin and vmax apply."
+            )
         if isinstance(norm, mcolors.Normalize):
             vmin = norm.vmin
             vmax = norm.vmax

ultraplot/tests/test_colorbar.py

@@ -1226,3 +1226,49 @@ def test_colorbar_span_position_matches_target_rows():
     ), f"Panel y0={panel_pos.y0:.3f} != row1 y0={row1_pos.y0:.3f}"
     # Sanity: panel must be taller than a single row
     assert panel_pos.height > row0_pos.height * 1.5
+
+
+@pytest.mark.parametrize(
+    "norm",
+    ["linear", ["linear"], ("linear",)],
+)
+def test_colorbar_norm_str_with_limits(norm):
+    """
+    Should allow to pass vmin or vmax when we are passing a norm specification
+    as a string, list, or tuple (per the ``constructor.Norm`` contract).
+    """
+    data = np.random.rand(10, 10)
+    fig, ax = uplt.subplots()
+    cm = ax.pcolormesh(data, vmin=0.1, norm=norm, vmax=1)
+    assert cm.norm.vmin == pytest.approx(0.1)
+    assert cm.norm.vmax == pytest.approx(1)
+
+
+@pytest.mark.parametrize(
+    "norm", [("linear", 0.1, 1), ["linear", 0.1, 1], ("linear", 0.1, 1, False)]
+)
+def test_colorbar_norm_tuple_positional_limits(norm):
+    """
+    Tuple / list form ``(name, vmin, vmax)`` should construct the normalizer
+    with the positional arguments and not collide with implicit vmin/vmax
+    kwargs when the user does not separately specify them.
+    """
+    data = np.random.rand(10, 10)
+    fig, ax = uplt.subplots()
+    cm = ax.pcolormesh(data, norm=norm)
+    assert cm.norm.vmin == pytest.approx(0.1)
+    assert cm.norm.vmax == pytest.approx(1)
+
+
+def test_colorbar_norm_with_limits():
+    """ "
+    Should allow to pass vmin or vmax when we are passing a str formatter
+    """
+    data = np.random.rand(10, 10)
+    fig = None
+    with pytest.raises(ValueError):
+        fig, ax = uplt.subplots()
+        ax.pcolormesh(
+            data, vmin=0, norm=uplt.colors.mcolors.Normalize(vmin=0, vmax=1), vmax=1
+        )
+    return fig