 applyFilter = do ->
   filters = {}
   (attrName, values) ->
-    filters[attrName] = values
+    if values?
+      filters[attrName] = values
+    else
+      delete filters[attrName]
+
     loadData filters
 
 

  #   colorsBetween("#e0f3f8","#313695", 6).reverse()  # negative
  #   .concat(colorsBetween("#e5f5e0","#00441b", 6))   # positive

  colorsBetween = (start, end, numColors) ->
    scale = d3.scale.linear()
      .range([start, end])

          #   if y1 <= 0
          #     negative = true
          #     continue
          #   canvas.fillRect i, y1 = ys(y1), 1, y0 - y1
          #   ++i

          for d in data
