Prevent exceptions on empty logarithmic graphs

pygal/graph/base.py

@@ -52,9 +52,10 @@ class BaseGraph(object):
         self.view = None
         if self.logarithmic and self.zero == 0:
             # Explicit min to avoid interpolation dependency
-            self.zero = min(filter(
+            positive_values = filter(
                 lambda x: x > 0,
-                [val for serie in self.series for val in serie.safe_values]))
+                [val for serie in self.series for val in serie.safe_values])
+            self.zero = min(positive_values) if positive_values else 0
         self._draw()
         self.svg.pre_render()
 

pygal/graph/graph.py

@@ -198,6 +198,7 @@ class Graph(BaseGraph):
             ))
             x = -5
             y = self.view.y(position)
+            if not y: continue
             if draw_axes:
                 self.svg.node(
                     guides, 'path',

pygal/view.py

@@ -293,8 +293,8 @@ class LogView(View):
         self.width = width
         self.height = height
         self.box = box
-        self.log10_ymax = log10(self.box.ymax)
+        self.log10_ymax = log10(self.box.ymax) if self.box.ymax > 0 else 0
-        self.log10_ymin = log10(self.box.ymin)
+        self.log10_ymin = log10(self.box.ymin) if self.box.ymin > 0 else 0
         self.box.fix(False)
 
     # pylint: enable-msg=W0231