Support for negative bars and columns. Closes #52.

wireservice · May 20, 2016 · f6bf87f · f6bf87f
1 parent a8f027f
commit f6bf87f
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Showing 3 changed files with 29 additions and 26 deletions.
diff --git a/leather/shapes/bars.py b/leather/shapes/bars.py
@@ -25,22 +25,31 @@ def to_svg(self, width, height, x_scale, y_scale, series):
         group = ET.Element('g')
         group.set('class', 'series bars')
 
+        zero_x = x_scale.project(0, 0, width)
+
         for i, (x, y, row) in enumerate(series):
             if x is None or y is None:
                 continue
 
-            proj_x = x_scale.project(x, 0, width)
             y1, y2 = y_scale.project_interval(y, height, 0)
+            proj_x = x_scale.project(x, 0, width)
+
+            if x < 0:
+                bar_x = proj_x
+                bar_width = zero_x - proj_x
+            else:
+                bar_x = zero_x
+                bar_width = proj_x - zero_x
 
             if callable(self._fill_color):
                 color = self._fill_color(x, y, row, i)
             else:
                 color = self._fill_color
 
             group.append(ET.Element('rect',
-                x=six.text_type(0),
+                x=six.text_type(bar_x),
                 y=six.text_type(y2),
-                width=six.text_type(proj_x),
+                width=six.text_type(bar_width),
                 height=six.text_type(y1 - y2),
                 fill=color
             ))

diff --git a/leather/shapes/columns.py b/leather/shapes/columns.py
@@ -25,23 +25,32 @@ def to_svg(self, width, height, x_scale, y_scale, series):
         group = ET.Element('g')
         group.set('class', 'series columns')
 
+        zero_y = y_scale.project(0, height, 0)
+
         for i, (x, y, row) in enumerate(series):
             if x is None or y is None:
                 continue
 
             x1, x2 = x_scale.project_interval(x, 0, width)
             proj_y = y_scale.project(y, height, 0)
 
+            if y < 0:
+                column_y = zero_y
+                column_height = proj_y - zero_y
+            else:
+                column_y = proj_y
+                column_height = zero_y - proj_y
+
             if callable(self._fill_color):
                 color = self._fill_color(x, y, row, i)
             else:
                 color = self._fill_color
 
             group.append(ET.Element('rect',
                 x=six.text_type(x1),
-                y=six.text_type(proj_y),
+                y=six.text_type(column_y),
                 width=six.text_type(x2 - x1),
-                height=six.text_type(height - proj_y),
+                height=six.text_type(column_height),
                 fill=color
             ))
 

diff --git a/test.py b/test.py
@@ -1,26 +1,11 @@
 import leather
 
-data1    = [
-    (0, 3),
-    (4, 5),
-    (7, 9),
-    (8, 4)
+data = [
+    (-3, 'foo', -3),
+    (5, 'bar', 5),
+    (-9, 'baz', -9)
 ]
 
-data2 = [
-    (2, 4),
-    (7, 3),
-    (6, 2),
-    (5, 9)
-]
-
-data3 = [
-    (2, 7),
-    (7, 2)
-]
-
-chart = leather.Chart('Multiple series')
-chart.add_dots(data1, name="This is a really insanely long series name......")
-chart.add_dots(data2, name="And this one is almost as long!")
-chart.add_dots(data3, name="But this one's short.")
+chart = leather.Chart('Negative columns')
+chart.add_bars(data)
 chart.to_svg('test.svg')