Distance Matrix: Show negative distances using divergent palettes

maze516 · Feb 3, 2023 · df24757 · df24757
1 parent 0dec358
commit df24757
Showing 1 changed file with 22 additions and 5 deletions.
diff --git a/Orange/widgets/utils/distmatrixmodel.py b/Orange/widgets/utils/distmatrixmodel.py
@@ -8,6 +8,7 @@
 
 from Orange.misc import DistMatrix
 from Orange.widgets import gui
+from Orange.widgets.utils import colorpalettes
 from Orange.widgets.utils.itemdelegates import FixedFormatNumericColumnDelegate
 
 
@@ -17,10 +18,19 @@ class LabelData(NamedTuple):
 
 
 class DistMatrixModel(QAbstractTableModel):
+    _brushes = np.array([QBrush(QColor.fromHsv(120, int(i / 255 * 170), 255))
+                         for i in range(256)])
+
+    _diverging_brushes = np.array([
+        QBrush(col) for col in
+        colorpalettes.ContinuousPalettes['diverging_tritanopic_cwr_75_98_c20'
+        ].qcolors])
+
     def __init__(self):
         super().__init__()
         self.distances: Optional[DistMatrix] = None
         self.colors: Optional[np.ndarray] = None
+        self.brushes: Optional[np.ndarray] = None
         self.__header_data: Dict[Any, Optional[LabelData]] = {
             Qt.Horizontal: LabelData(),
             Qt.Vertical: LabelData()}
@@ -35,12 +45,19 @@ def set_data(self, distances):
         self.distances = distances
         self.__header_data = dict.fromkeys(self.__header_data, LabelData())
         if distances is None:
-            self.__span = self.colors = None
+            self.__span = self.colors = self.brushes = None
             return
-        self.__span = span = np.max(distances)
+        minc = min(0, np.min(distances))
+        maxc = np.max(distances)
+        if minc < 0:
+            self.__span = max(-minc, maxc)
+            self.brushes = self._diverging_brushes
+            self.colors = 127 + (distances / self.__span * 128).astype(int)
+        else:
+            self.__span = maxc
+            self.brushes = self._brushes
+            self.colors = (distances / self.__span * 255).astype(int)
 
-        self.colors = \
-            (distances * (170 / span if span > 1e-10 else 0)).astype(int)
         self.__zero_diag = \
             distances.is_symmetric() and np.allclose(np.diag(distances), 0)
         self.endResetModel()
@@ -73,7 +90,7 @@ def data(self, index, role=Qt.DisplayRole):
         if role == Qt.DisplayRole and not (self.__zero_diag and row == col):
             return float(self.distances[row, col])
         if role == Qt.BackgroundRole:
-            return QBrush(QColor.fromHsv(120, self.colors[row, col], 255))
+            return self.brushes[self.colors[row, col]]
         if role == Qt.ForegroundRole:
             return QColor(Qt.black)  # the background is light-ish
         if role == FixedFormatNumericColumnDelegate.ColumnDataSpanRole: