Allow gaps between histogram bars and fix axis labels

doc/PlotlyViewerExample.ipynb

@@ -161,6 +161,25 @@
     "# viewer = app.new_data_viewer(PlotlyHistogramView, data=data)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "26be6106-c61a-4d84-82e3-136ccfcee588",
+   "metadata": {},
+   "source": [
+    "You can adjust whether there are gaps between the bars and, if so, what fraction of the plot they occupy"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "821b6397-80e2-443c-b6c3-50bf954abbf2",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "histogram_viewer.state.gaps = True\n",
+    "histogram_viewer.state.gap_fraction = 0.15"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "588347a7-8f4d-4f47-9838-a4a2e4106b02",

glue_plotly/viewers/common/viewer.py

@@ -96,10 +96,10 @@ def axis_y(self):
         return self.figure.layout.yaxis
 
     def update_x_axislabel(self, label):
-        self.axis_x['title'] = label
+        self.axis_x['title'].update(text=label)
 
     def update_y_axislabel(self, label):
-        self.axis_y['title'] = label
+        self.axis_y['title'].update(text=label)
 
     def _update_selection_layer_bounds(self):
         x0 = 0.5 * (self.state.x_min + self.state.x_max)

glue_plotly/viewers/histogram/state.py

@@ -0,0 +1,17 @@
+from glue.viewers.histogram.state import DDCProperty, HistogramViewerState
+
+
+__all__ = ["PlotlyHistogramViewerState"]
+
+
+class PlotlyHistogramViewerState(HistogramViewerState):
+
+    gaps = DDCProperty(False, docstring='Whether to include gaps between histogram bars')
+    gap_fraction = DDCProperty(0.15,
+                               docstring='The gap fraction if using gaps. For example, '
+                                         '0 means that no gap between bars, 0.5 means '
+                                         'that the bars and gaps are evenly sized, and 1 '
+                                         'means that the entire bar mark is gap.')
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)

glue_plotly/viewers/histogram/tests/test_viewer.py

@@ -0,0 +1,77 @@
+from glue.core import Data
+from glue_jupyter import JupyterApplication
+from plotly.graph_objects import Bar
+
+from glue_plotly.common import DEFAULT_FONT
+from glue_plotly.viewers.histogram import PlotlyHistogramView
+
+
+class TestHistogramViewer:
+
+    def setup_method(self, method):
+        self.data = Data(label="histogram", x=[1, 1, 1, 2, 2, 3, 3, 3, 4, 6, 6])
+        self.app = JupyterApplication()
+        self.app.session.data_collection.append(self.data)
+        self.viewer = self.app.new_data_viewer(PlotlyHistogramView)
+        self.viewer.add_data(self.data)
+
+        viewer_state = self.viewer.state
+        viewer_state.x_min = 0.5
+        viewer_state.hist_x_min = 0.5
+        viewer_state.x_max = 6.5
+        viewer_state.hist_x_max = 6.5
+        viewer_state.hist_n_bin = 6
+        viewer_state.y_min = 0
+        viewer_state.y_max = 5
+        viewer_state.x_axislabel = 'X Axis'
+        viewer_state.y_axislabel = 'Y Axis'
+        viewer_state.normalize = False
+
+        self.layer = self.viewer.layers[0]
+        self.layer.state.color = "#abcdef"
+        self.layer.state.alpha = 0.75
+
+    def teardown_method(self, method):
+        self.viewer = None
+        self.app = None
+
+    def test_basic(self):
+        assert len(self.viewer.layers) == 1
+        traces = list(self.layer.traces())
+        assert len(traces) == 1
+        bars = traces[0]
+        assert isinstance(bars, Bar)
+        assert bars.marker.color == "#abcdef"
+        assert bars.marker.opacity == 0.75
+        assert bars.x == tuple(range(1, 7))
+        expected_y = [3, 2, 3, 1, 0, 2]
+        assert all(a == b for a, b in zip(bars.y, expected_y))
+
+    def test_axes(self):
+        x_axis = self.viewer.figure.layout.xaxis
+        y_axis = self.viewer.figure.layout.yaxis
+
+        assert x_axis.title.text == 'X Axis'
+        assert y_axis.title.text == 'Y Axis'
+        assert x_axis.type == 'linear'
+        assert y_axis.type == 'linear'
+
+        assert x_axis.range == (0.5, 6.5)
+        assert y_axis.range == (0, 5)
+
+        assert all(f.family == DEFAULT_FONT for f in
+                   (x_axis.title.font, x_axis.tickfont, y_axis.title.font, y_axis.tickfont))
+
+        common_items = dict(showgrid=False, showline=False, mirror=True, rangemode='normal',
+                            zeroline=False, showspikes=False, showticklabels=True)
+        for axis in x_axis, y_axis:
+            assert all(axis[key] == value for key, value in common_items.items())
+
+    def test_gaps(self):
+        assert self.viewer.figure.layout.bargap == 0
+        self.viewer.state.gaps = True
+        assert self.viewer.figure.layout.bargap == 0.15
+        self.viewer.state.gap_fraction = 0.36
+        assert self.viewer.figure.layout.bargap == 0.36
+        self.viewer.state.gaps = False
+        assert self.viewer.figure.layout.bargap == 0

glue_plotly/viewers/histogram/viewer.py

@@ -1,12 +1,12 @@
 from glue.core.subset import XRangeROI, roi_to_subset_state
-from glue.viewers.histogram.state import HistogramViewerState
 from glue_plotly.common import base_layout_config, base_rectilinear_axis
 from glue_plotly.viewers import PlotlyBaseView
 from glue_plotly.viewers.histogram.layer_artist import PlotlyHistogramLayerArtist
 
 from glue_jupyter.registries import viewer_registry
 from glue_jupyter.common.state_widgets.layer_histogram import HistogramLayerStateWidget
 from glue_jupyter.common.state_widgets.viewer_histogram import HistogramViewerStateWidget
+from glue_plotly.viewers.histogram.state import PlotlyHistogramViewerState
 
 
 __all__ = ["PlotlyHistogramView"]
@@ -22,7 +22,7 @@ class PlotlyHistogramView(PlotlyBaseView):
     allow_duplicate_data = False
     allow_duplicate_subset = False
 
-    _state_cls = HistogramViewerState
+    _state_cls = PlotlyHistogramViewerState
     _options_cls = HistogramViewerStateWidget
     _data_artist_cls = PlotlyHistogramLayerArtist
     _subset_artist_cls = PlotlyHistogramLayerArtist
@@ -32,6 +32,8 @@ def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.state.add_callback('x_att', self._update_axes)
         self.state.add_callback('normalize', self._update_axes)
+        self.state.add_callback('gaps', self._gaps_changed)
+        self.state.add_callback('gap_fraction', self._gaps_changed)
         self._update_axes()
 
     def _create_layout_config(self):
@@ -54,6 +56,10 @@ def _update_axes(self, *args):
         else:
             self.state.y_axislabel = 'Number'
 
+    def _gaps_changed(self, *args):
+        gap = self.state.gap_fraction if self.state.gaps else 0
+        self.figure.layout.update(bargap=gap)
+
     def _roi_to_subset_state(self, roi):
         return roi_to_subset_state(roi, x_att=self.state.x_att)