fix(crosssection): make view x/y override symmetric, validate input

autotest/test_plot_cross_section.py

@@ -195,6 +195,56 @@ def test_cross_section_invalid_line_representations_fail(line):
         flopy.plot.PlotCrossSection(modelgrid=grid, line={"line": line})
 
 
+@requires_pkg("shapely")
+@pytest.mark.parametrize("view", ["bogus", "diagonal", "X", "Y"])
+def test_cross_section_invalid_view_raises_error(view):
+    grid = structured_square_grid(side=10)
+    if view in ("X", "Y"):
+        # view is case-insensitive, these should not raise
+        flopy.plot.PlotCrossSection(
+            modelgrid=grid, line={"line": [(0, 0), (10, 10)]}, view=view
+        )
+        return
+    with pytest.raises(ValueError):
+        flopy.plot.PlotCrossSection(
+            modelgrid=grid, line={"line": [(0, 0), (10, 10)]}, view=view
+        )
+
+
+@requires_pkg("shapely")
+@pytest.mark.parametrize(
+    "line, expected_auto_direction",
+    [
+        # horizontal: x-span > y-span
+        ([(0, 5.5), (10, 5.5)], "x"),
+        # vertical: y-span > x-span
+        ([(5.5, 0), (5.5, 10)], "y"),
+        # diagonal, equal spans: falls to the "else" (y) branch since the
+        # comparison is a strict ">"
+        ([(0, 0), (10, 10)], "y"),
+    ],
+)
+def test_cross_section_view_forces_direction(line, expected_auto_direction):
+    grid = structured_square_grid(side=10)
+
+    auto_xc = flopy.plot.PlotCrossSection(modelgrid=grid, line={"line": line})
+    assert auto_xc.direction == expected_auto_direction
+
+    x_xc = flopy.plot.PlotCrossSection(modelgrid=grid, line={"line": line}, view="x")
+    assert x_xc.direction == "x"
+
+    y_xc = flopy.plot.PlotCrossSection(modelgrid=grid, line={"line": line}, view="y")
+    assert y_xc.direction == "y"
+
+
+@pytest.mark.parametrize("onkey, expected_direction", [("row", "x"), ("column", "y")])
+@pytest.mark.parametrize("view", ["auto", "x", "y"])
+def test_cross_section_view_ignored_for_row_column(onkey, expected_direction, view):
+    grid = structured_square_grid(side=10)
+    xc = flopy.plot.PlotCrossSection(modelgrid=grid, line={onkey: 4}, view=view)
+    assert xc.direction == expected_direction
+
+
 def test_plot_limits():
     xymin, xymax = 0, 1000
     cellsize = 50

flopy/plot/crosssection.py

@@ -52,12 +52,16 @@ class PlotCrossSection:
         cross-sectional width less than min_segment_length will be ignored
         and not included in the plot. Default is 1e-02.
     view : str
-        view can be used to force the view of the cross section when a line is provided.
-        "auto" is default and mimics the long term behavior of flopy, which decides
-        on the view by taking the maximum of the x and y direction of the cross
-        sectional line. "x" forces the view to be plotted from the x direction
-        (bottom of the unrotated grid). and "y" forces the view to be plotted from the
-        y-direction "left" or "right" side of the unrotated grid.
+        view can be used to force the view of the cross section when an
+        arbitrary line (line["line"]) is provided. "auto" is default and
+        mimics the long term behavior of flopy, which decides on the view
+        by taking the maximum of the x and y direction of the cross
+        sectional line. "x" forces the view to be plotted from the x
+        direction (bottom of the unrotated grid) and "y" forces the view to
+        be plotted from the y-direction ("left" or "right" side of the
+        unrotated grid). view has no effect when the cross section is
+        specified with line["row"] or line["column"], since the view is
+        already unambiguous in that case.
     """
 
     def __init__(
@@ -72,6 +76,8 @@ def __init__(
         view="auto",
     ):
         view = view.lower()
+        if view not in ("auto", "x", "y"):
+            raise ValueError(f"view must be 'auto', 'x', or 'y', got {view!r}")
         self.ax = ax
         self.geographic_coords = geographic_coords
         self.model = model
@@ -168,10 +174,8 @@ def __init__(
                 yp.append(v2)
 
             xp, yp = self.mg.get_local_coords(xp, yp)
-            if (np.max(xp) - np.min(xp) > np.max(yp) - np.min(yp)) or view not in (
-                "auto",
-                "y",
-            ):
+            xspan_gt_yspan = np.max(xp) - np.min(xp) > np.max(yp) - np.min(yp)
+            if view == "x" or (view == "auto" and xspan_gt_yspan):
                 # this is x-projection and we should buffer x by small amount
                 idx0 = np.argmax(xp)
                 idx1 = np.argmin(xp)