explicitly override minor locator if given (#96)

* explicitly override minor locator if given

* removed print statement

* added comment

* black formatting

* added comments to unittest

* add return

Author: cvanelteren

ultraplot/axes/base.py

@@ -1159,6 +1159,7 @@ def _add_colorbar(
                     locator = mticker.FixedLocator(ticks)
                 else:
                     locator = pticker.DiscreteLocator(ticks)
+
             if tickminor and minorlocator is None:
                 minorlocator = pticker.DiscreteLocator(ticks, minor=True)
 
@@ -1213,6 +1214,10 @@ def _add_colorbar(
         # obj.minorlocator = minorlocator  # backwards compatibility
         obj.update_ticks = guides._update_ticks.__get__(obj)  # backwards compatible
         if minorlocator is not None:
+            # Note we make use of mpl's setters and getters
+            current = obj.minorlocator
+            if current != minorlocator:
+                obj.minorlocator = minorlocator
             obj.update_ticks()
         elif tickminor:
             obj.minorticks_on()

ultraplot/tests/test_colorbar.py

@@ -251,3 +251,20 @@ def test_reversed_levels():
                 ax.pcolormesh(data, colorbar="b", **kw)
                 i += 1
     return fig
+
+
+@pytest.mark.mpl_image_compare
+def test_minor_override():
+    """Test minor ticks override."""
+    # Setting a custom minor tick should override the settings. Here we set the ticks to 1 and the minorticks to half that. We then check that the minor ticks are set correctly
+    data = state.rand(10, 10)
+    left, right, minor, n = 0, 1, 0.05, 11
+    levels = np.linspace(left, right, n)
+    fig, ax = uplt.subplots()
+    m = ax.pcolormesh(data, colorbar="b", levels=levels)
+    cax = ax.colorbar(m, minorticks=minor)
+    assert np.allclose(
+        cax.minorlocator.tick_values(left, right),
+        np.linspace(left - minor, right + minor, n * 2 + 1),
+    )
+    return fig