                g = data.geno[marker][i]
                return "2" if g < 0
                "1")
+          .on("mouseover", indtip)
+          .on("mouseout", -> d3.selectAll("#indtip").remove())
+
 
   # function to revise phenotype vs genotype plot
   revPXG = (chr, marker) ->

            "red")
         .attr("stroke", "black")
         .attr("stroke-width", "2")


  # background rectangles for each chromosome, alternate color

          .attr("opacity", 0)
          .on("mouseover", (td) ->
                 d3.select(this).attr("opacity", 1) unless markerClick[td]
                 martip.call(this,td))
          .on "mouseout", (td) ->
                 d3.select(this).attr("opacity", markerClick[td])
                 d3.selectAll("#martip").remove()
          .on "click", (td) ->
                 pos = data.lod[chr].pos[data.markerindex[chr][td]]
                 title = "#{td} (chr #{chr}, #{onedig(pos)} cM)"
