githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/data_connectedscatter.csv", function(data) {

    // List of groups (here I have one group per column)
    var allGroup = ["valueA", "valueB", "valueC"]

    // add the options to the button
    d3.select("#selectButton")
      .selectAll('myOptions')
     	.data(allGroup)
      .enter()
    	.append('option')
      .text(function (d) { return d; }) // text showed in the menu
      .attr("value", function (d) { return d; }) // corresponding value ret