     w = Math.round((width-chrGap*data.chrnames.length)/totalChrLength*chrLength[i])
     data.chrEnd.push(cur + w)
     cur = data.chrEnd[i] + chrGap
+    # x-axis scales, by chromosome
     data.xscale[chr] = d3.scale.linear()
                          .domain([chrStart[i], chrEnd[i]])
                          .range([data.chrStart[i], data.chrEnd[i]])
 
+  # return data with new stuff added
   data

       .attr("stroke-width", "none")

  ## configuration parameters

  chart.width = (value) ->
    if !arguments.length
      return width

                    .attr("r", pointsize)
                    .attr("fill", pointcolor)
                    .attr("pointer-events", "hidden")
      # these hidden points are what gets selected...a bit larger
      hiddenpoints = g.append("g").attr("id", "markerpoints_hidden")
      markerSelect =
        hiddenpoints.selectAll("empty")
