OWBoxPlot: Fix crash on discrete variables with no values

Orange/widgets/visualize/owboxplot.py

@@ -297,6 +297,8 @@ def compute_score(attr):
             else:
                 # Chi-square with the given distribution into groups
                 # (see degrees of freedom in computation of the p-value)
+                if not attr.values or not group_var.values:
+                    return 2
                 observed = np.array(
                     contingency.get_contingency(data, group_var, attr))
                 observed = observed[observed.sum(axis=1) != 0, :]
@@ -368,10 +370,11 @@ def compute_box_data(self):
         if not attr:
             return
         dataset = self.dataset
-        if dataset is None:
+        self.is_continuous = attr.is_continuous
+        if dataset is None or not self.is_continuous and not attr.values or \
+                        self.group_var and not self.group_var.values:
             self.stats = self.dist = self.conts = []
             return
-        self.is_continuous = attr.is_continuous
         if self.group_var:
             self.dist = []
             self.conts = contingency.get_contingency(
@@ -554,6 +557,8 @@ def stat_ttest():
             df = pooled_var ** 2 / \
                 ((d1.var / d1.n) ** 2 / (d1.n - 1) +
                  (d2.var / d2.n) ** 2 / (d2.n - 1))
+            if pooled_var == 0:
+                return np.nan, np.nan
             t = abs(d1.mean - d2.mean) / math.sqrt(pooled_var)
             p = 2 * (1 - scipy.special.stdtr(df, t))
             return t, p

Orange/widgets/visualize/tests/test_owboxplot.py

@@ -56,15 +56,37 @@ def test_input_data_missings_cont_no_group_var(self):
     def test_input_data_missings_disc_group_var(self):
         """Check widget with discrete data with missing values and group variable"""
         data = self.zoo
-        data.X[:, 0] = np.nan
+        data.X[:, 1] = np.nan
+        data.domain.attributes[1].values = []
         self.send_signal("Data", data)
+        self.widget.controls.order_by_importance.setChecked(True)
+        self._select_list_items(self.widget.controls.attribute)
+        self._select_list_items(self.widget.controls.group_var)
 
     def test_input_data_missings_disc_no_group_var(self):
         """Check widget discrete data with missing values and no group variable"""
         data = self.zoo
         data.domain.class_var = ContinuousVariable("cls")
-        data.X[:, 0] = np.nan
+        data.X[:, 1] = np.nan
+        data.domain.attributes[1].values = []
+        self.send_signal("Data", data)
+        self.widget.controls.order_by_importance.setChecked(True)
+        self._select_list_items(self.widget.controls.attribute)
+        self._select_list_items(self.widget.controls.group_var)
+
+    def test_attribute_combinations(self):
+        data = Table("anneal")
         self.send_signal("Data", data)
+        group_list = self.widget.controls.group_var
+        m = group_list.selectionModel()
+        for i in range(len(group_list.model())):
+            m.setCurrentIndex(group_list.model().index(i), m.ClearAndSelect)
+            self._select_list_items(self.widget.controls.attribute)
+
+    def _select_list_items(self, _list):
+        model = _list.selectionModel()
+        for i in range(len(_list.model())):
+            model.setCurrentIndex(_list.model().index(i), model.ClearAndSelect)
 
     def test_apply_sorting(self):
         controls = self.widget.controls