cherry-pick https://github.com/Shopify/dashing/pull/513/files

Author: gottfrois

vendor/assets/javascripts/dashing/default_widgets/graph.coffee

@@ -11,6 +11,37 @@ class Dashing.Graph extends Dashing.Widget
     # Gross hacks. Let's fix this.
     width = (Dashing.widget_base_dimensions[0] * container.data("sizex")) + Dashing.widget_margins[0] * 2 * (container.data("sizex") - 1)
     height = (Dashing.widget_base_dimensions[1] * container.data("sizey"))
+
+    y_scale_type = @get("yscale")
+
+    # If log scale is requested or required, we need to know the range to populate the axis
+    min = Number.MAX_VALUE
+    max = Number.MIN_VALUE
+    data = [ {x:0, y:0} ]
+    data = @get('points') if @get('points')
+
+    for d in data
+       min = Math.min(min, d.y)
+       max = Math.max(max, d.y)
+
+    if (!y_scale_type)
+       if ((min>0 && max>0 && max/min>500) || (min<0 && max<0 && min/max>500))
+          y_scale_type = 'log'
+       else
+          y_scale_type = 'linear'
+
+    if y_scale_type.match ///log(?:\(((?:\d+(?:\.\d+)?)|e)\))?///
+       y_base=RegExp.$1 || 10
+       (y_base=="e") && (y_base=Math.E)
+       y_scale=d3.scale.log().base(y_base).domain([min, max])
+       log_y_scale_base=Math.log(y_scale.base())
+       tickValues=[]
+       for p in [Math.ceil(Math.log(min)/log_y_scale_base)..Math.floor(Math.log(max)/log_y_scale_base)] by 1
+           tickValues.push(Math.pow(y_base,p))
+    else
+       y_scale=d3.scale.linear()
+       tickValues=null
+
     @graph = new Rickshaw.Graph(
       element: @node
       width: width
@@ -19,16 +50,16 @@ class Dashing.Graph extends Dashing.Widget
       series: [
         {
         color: "#fff",
-        data: [{x:0, y:0}]
+        data: data
+        scale: y_scale
         }
       ]
-      padding: {top: 0.02, left: 0.02, right: 0.02, bottom: 0.02}
     )
 
     @graph.series[0].data = @get('points') if @get('points')
 
-    x_axis = new Rickshaw.Graph.Axis.Time(graph: @graph)
-    y_axis = new Rickshaw.Graph.Axis.Y(graph: @graph, tickFormat: Rickshaw.Fixtures.Number.formatKMBT)
+    x_axis = new Rickshaw.Graph.Axis.Time(graph: @graph, timeFixture: new Rickshaw.Fixtures.Time.Local())
+    y_axis = new Rickshaw.Graph.Axis.Y.Scaled(graph: @graph, tickFormat: Rickshaw.Fixtures.Number.formatKMBT, scale:y_scale, tickValues: tickValues)
     @graph.render()
 
   onData: (data) ->