Added secondary axis support to Line

pygal/graph/__init__.py

@@ -36,5 +36,4 @@ CHARTS_NAMES = [
     'VerticalPyramid',
     'Dot',
     'Gauge',
-    'DoubleYLine',
 ]

pygal/graph/line.py

@@ -48,9 +48,13 @@ class Line(Graph):
                 values +
                 [(values[-1][0], zero)])
 
-    def line(self, serie_node, serie):
+    def line(self, serie_node, serie, rescale=False):
         """Draw the line serie"""
-        view_values = map(self.view, serie.points)
+        if rescale and self.secondary_series:
+            points = list ((x, self._scale_diff+(y - self._scale_min_2nd) * self._scale) for x, y in serie.points)
+        else:
+            points = serie.points
+        view_values = map(self.view, points)
         if self.show_dots:
             for i, (x, y) in enumerate(view_values):
                 if None in (x, y):
@@ -87,12 +91,23 @@ class Line(Graph):
                 class_='line reactive' + (' nofill' if not self.fill else ''))
 
     def _compute(self):
+        # X Labels
         x_pos = [
             x / (self._len - 1) for x in range(self._len)
         ] if self._len != 1 else [.5]  # Center if only one value
 
+        # XXX: we need to have rescaled serie.values to execute this
         self._points(x_pos)
 
+        x_labels = zip(self.x_labels, x_pos)
+
+        if self.x_labels_num_limit and len(x_labels)>self.x_labels_num_limit:
+            step = (len(x_labels)-1)/(self.x_labels_num_limit-1)
+            x_labels = list(x_labels[int(i*step)] for i in range(self.x_labels_num_limit))
+
+        self._x_labels = self.x_labels and x_labels
+        # Y Label
+
         if self.include_x_axis:
             self._box.ymin = min(self._min, 0)
             self._box.ymax = max(self._max, 0)
@@ -104,15 +119,32 @@ class Line(Graph):
             self._box.ymin, self._box.ymax, self.logarithmic, self.order_min
         ) if not self.y_labels else map(float, self.y_labels)
 
-        x_labels = zip(self.x_labels, x_pos)
+        self._y_labels = zip(map(self._format, y_pos), y_pos)
+        # secondary y axis support
+        if self.secondary_series:
+            if self.include_x_axis:
+                ymin = min(self._secondary_min, 0)
+                ymax = max(self._secondary_max, 0)
+            else:
+                ymin = self._secondary_min
+                ymax = self._secondary_max
+            print("ymin: %f, ymax: %f" % (ymin, ymax))
+            steps = len(y_pos)
+            left_range = abs(y_pos[-1] -  y_pos[0])
+            right_range = abs(ymax - ymin)
+            scale = right_range / (steps-1)
+            self._y_2nd_labels = list((self._format(ymin+i*scale), pos) for i, pos in enumerate(y_pos))
+
+            min_2nd = float(self._y_2nd_labels[0][0])
+            self._scale = left_range / right_range
+            self._scale_diff = y_pos[0]
+            self._scale_min_2nd = min_2nd
+
 
-        if self.x_labels_num_limit and len(x_labels)>self.x_labels_num_limit:
-            step = (len(x_labels)-1)/(self.x_labels_num_limit-1)
-            x_labels = list(x_labels[int(i*step)] for i in range(self.x_labels_num_limit))
 
-        self._x_labels = self.x_labels and x_labels
-        self._y_labels = zip(map(self._format, y_pos), y_pos)
 
     def _plot(self):
         for index, serie in enumerate(self.series):
             self.line(self._serie(index), serie)
+        for index, serie in enumerate(self.secondary_series, len(self.series)):
+            self.line(self._serie(index), serie, True)