for (ind=0; ind<unique_values.length; ind++){
    dataset_a=dataset.filter(function(d) { return (d.o_name==unique_values[ind])})
    var linegraph=svg.append("path")
           .attr("d", lineFunction(dataset_a))
           .attr("stroke", cScale(ind))
           .on("click", function(d){
                            d3.select(this).remove()});
  } // end ind