Make blank plot instead of raising on all nan

src/plopp/core/limits.py

@@ -59,7 +59,7 @@ def find_limits(
     v = x.values
     finite_inds = np.isfinite(v)
     if np.sum(finite_inds) == 0:
-        raise ValueError("No finite values were found in array. Cannot compute limits.")
+        return (sc.scalar(np.nan, unit=x.unit), sc.scalar(np.nan, unit=x.unit))
     finite_vals = v[finite_inds]
     finite_max = None
     if scale == "log":
@@ -98,6 +98,8 @@ def fix_empty_range(
     """
     Range correction in case xmin == xmax
     """
+    if np.isnan(lims[0].value) or np.isnan(lims[1].value):
+        lims = (sc.scalar(0.0, unit=lims[0].unit), sc.scalar(0.0, unit=lims[1].unit))
     if lims[0].value != lims[1].value:
         return lims
     if lims[0].value == 0.0:

src/plopp/graphics/bbox.py

@@ -7,6 +7,7 @@
 from dataclasses import dataclass
 from typing import Literal
 
+import numpy as np
 import scipp as sc
 
 from ..core.limits import find_limits, fix_empty_range
@@ -108,7 +109,11 @@ def axis_bounds(
         Whether to pad the limits.
     """
     try:
-        values = fix_empty_range(find_limits(x, scale=scale, pad=pad))
+        values = find_limits(x, scale=scale, pad=pad)
+        if np.isnan(values[0].value) or np.isnan(values[1].value):
+            return dict.fromkeys(keys, None)
+        else:
+            values = fix_empty_range(values)
     except ValueError:
         return dict.fromkeys(keys, None)
     bounds = dict(zip(keys, (val.value for val in values), strict=True))

tests/core/limits_test.py

@@ -2,7 +2,6 @@
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 
 import numpy as np
-import pytest
 import scipp as sc
 
 from plopp.core.limits import find_limits, fix_empty_range
@@ -53,12 +52,15 @@ def test_find_limits_with_ninf():
     assert sc.identical(lims[1], sc.scalar(10.0, unit='m'))
 
 
-def test_find_limits_no_finite_values_raises():
+def test_find_limits_no_finite_values_returns_nan_range():
     da = sc.DataArray(
         data=sc.array(dims=['x'], values=[np.nan, np.inf, -np.inf, np.nan], unit='m')
     )
-    with pytest.raises(ValueError, match="No finite values were found in array"):
-        _ = find_limits(da)
+    lims = find_limits(da)
+    assert np.isnan(lims[0].value)
+    assert np.isnan(lims[1].value)
+    assert lims[0].unit == 'm'
+    assert lims[1].unit == 'm'
 
 
 def test_find_limits_all_zeros():

tests/graphics/artists_test.py

@@ -3,7 +3,9 @@
 
 from functools import partial
 
+import numpy as np
 import pytest
+import scipp as sc
 
 import plopp as pp
 from plopp.data import examples
@@ -84,3 +86,50 @@ def test_opacity(self, set_backend, backend, func, data):
         assert artist.opacity in (None, 1.0)
         artist.opacity = 0.5
         assert artist.opacity == 0.5
+
+
+LINE_CASES = {k: v for k, v in CASES.items() if k.startswith("line")}
+
+
+@pytest.mark.parametrize(
+    ("backend", "func", "data"), LINE_CASES.values(), ids=LINE_CASES.keys()
+)
+class TestLineBBox:
+    def test_line_bbox(self, set_backend, backend, func, data):
+        fig = func(**data)
+        [artist] = fig.artists.values()
+        bbox = artist.bbox(xscale='linear', yscale='linear')
+        # Tolerance of 3 because there is padding around the line
+        assert np.isclose(bbox.xmin, data['obj'].coords['x'].min().value, atol=3.0)
+        assert np.isclose(bbox.xmax, data['obj'].coords['x'].max().value, atol=3.0)
+
+        if data['obj'].variances is not None:
+            ymin = (data['obj'] - sc.stddevs(data['obj'])).min()
+        else:
+            ymin = data['obj'].min()
+        # Tolerance of 0.2 because there is padding below the line
+        assert np.isclose(bbox.ymin, ymin.value, atol=0.2)
+
+        if data['obj'].variances is not None:
+            ymax = (data['obj'] + sc.stddevs(data['obj'])).max()
+        else:
+            ymax = data['obj'].max()
+        # Tolerance of 0.2 because there is padding above the line
+        assert np.isclose(bbox.ymax, ymax.value, atol=0.2)
+
+
+LINE_BACKENDS = {k: v[0] for k, v in CASES.items() if k.startswith("line")}
+
+
+@pytest.mark.parametrize(("backend"), LINE_BACKENDS.values(), ids=LINE_BACKENDS.keys())
+class TestLineBBoxAllNan:
+    def test_line_bbox_all_nan(self, set_backend, backend):
+        a = pp.data.data1d()
+        a.values[...] = np.nan
+        fig = pp.plot(obj=a)
+        [artist] = fig.artists.values()
+        bbox = artist.bbox(xscale='linear', yscale='linear')
+        assert bbox.xmin is not None
+        assert bbox.xmax is not None
+        assert bbox.ymin is None
+        assert bbox.ymax is None

tests/plotting/plot_1d_test.py

@@ -708,3 +708,9 @@ def test_plot_multiple_inputs_custom_type_keys():
 
     fig = pp.plot({A: a, B: b})
     assert len(fig.view.artists) == 2
+
+
+def test_plot_data_with_all_nans_does_not_raise():
+    da = data_array(ndim=1)
+    da.values[...] = np.nan
+    _ = da.plot()

tests/plotting/plot_2d_test.py

@@ -521,3 +521,9 @@ def test_clabel():
     da = data_array(ndim=2)
     fig = da.plot(clabel='MyColorLabel')
     assert fig.view.colormapper.clabel == 'MyColorLabel'
+
+
+def test_plot_data_with_all_nans_does_not_raise():
+    da = data_array(ndim=2)
+    da.values[...] = np.nan
+    _ = da.plot()

tests/plotting/slicer_test.py

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 
+import numpy as np
 import pytest
 import scipp as sc
 from scipp.testing import assert_allclose, assert_identical
@@ -240,6 +241,12 @@ def test_different_operations(self, operation, mode):
         da = data_array(ndim=2)
         SlicerPlot(da, keep=['xx'], mode=mode, operation=operation)
 
+    @pytest.mark.parametrize("mode", ["single", "range", "combined"])
+    def test_slicer_with_first_all_nan_slice_does_not_raise(self, mode):
+        da = data_array(ndim=2)
+        da['yy', 0].values[...] = np.nan
+        SlicerPlot(da, keep=['xx'], mode=mode)
+
 
 @pytest.mark.usefixtures("_parametrize_interactive_2d_backends")
 class TestSlicer2d:
@@ -407,3 +414,9 @@ def test_create_with_non_dimension_coord(self):
     def test_different_operations(self, operation, mode):
         da = data_array(ndim=3)
         SlicerPlot(da, keep=['xx', 'yy'], mode=mode, operation=operation)
+
+    @pytest.mark.parametrize("mode", ["single", "range", "combined"])
+    def test_slicer_with_first_all_nan_slice_does_not_raise(self, mode):
+        da = data_array(ndim=3)
+        da['zz', 0].values[...] = np.nan
+        SlicerPlot(da, keep=['xx'], mode=mode)