1141 | Validate canvas width, height

datashader/core.py

@@ -1227,9 +1227,14 @@ def validate_ranges(self, x_range, y_range):
         self.x_axis.validate(x_range)
         self.y_axis.validate(y_range)
 
+    def validate_extend(self, width, height):
+        if width == 0 or height == 0:
+            raise ValueError("Invalid extend plot_width and plot_height must be bigger than 0")
+
     def validate(self):
         """Check that parameter settings are valid for this object"""
         self.validate_ranges(self.x_range, self.y_range)
+        self.validate_extend(self.plot_width, self.plot_height)
 
 
 def bypixel(source, canvas, glyph, agg, *, antialias=False):

datashader/tests/test_dask.py

@@ -1564,3 +1564,18 @@ def test_line_antialias_where(npartitions):
             sol_where_min[j, i] = agg_where_min[j, i] = nan
 
     assert_eq_ndarray(agg_where_min.data, sol_where_min)
+
+def test_canvas_extend():
+
+    cvs_list = [
+        ds.Canvas(plot_width=0, plot_height=6),
+        ds.Canvas(plot_width=5, plot_height=0),
+        ds.Canvas(plot_width=0, plot_height=0)
+    ]
+    msg = r'Invalid extend plot_width and plot_height must be bigger than 0'
+    df = pd.DataFrame(dict(x=[0, 0.2, 1], y=[0, 0.4, 1], z=[10, 20, 30]))
+    ddf = dd.from_pandas(df, 1)
+    for cvs in cvs_list:
+        with pytest.raises(ValueError, match=msg): 
+            cvs.points(ddf, "x", "y", ds.mean("z"))
+

datashader/tests/test_pandas.py

@@ -2393,3 +2393,20 @@ def test_line_coordinate_lengths():
     for ny in (1, 3):
         with pytest.raises(ValueError, match=msg):
             cvs.line(source=df, x=["x0", "x1"], y=np.arange(ny), axis=1)
+
+
+
+def test_canvas_extend():
+
+    cvs_list = [
+        ds.Canvas(plot_width=0, plot_height=6),
+        ds.Canvas(plot_width=5, plot_height=0),
+        ds.Canvas(plot_width=0, plot_height=0)
+    ]
+    msg = r'Invalid extend plot_width and plot_height must be bigger than 0'
+    df = pd.DataFrame(dict(x=[0, 0.2, 1], y=[0, 0.4, 1], z=[10, 20, 30]))
+
+    for cvs in cvs_list:
+        with pytest.raises(ValueError, match=msg): 
+            cvs.points(df, "x", "y", ds.mean("z"))
+