var pointGroup = stereonetGroup.append('g')
this.addPoints = function(pointData, settings) {
  var plottedData = pointGroup.selectAll('circle').data()
  var combinedData = pointData.concat(plottedData)
  console.log(combinedData)
  console.log(plottedData.length,pointData.length)
  var structurePoints = pointGroup.selectAll('circle')
    .data(combinedData.filter(function(datum) {
      if (datum.orientable != 'N') {
        return datum
      }
    }))
    .enter()
    .append('circle')

  var structurePointAttributes = structurePoints
    .attr('cx', function(d) { return xScale(cnijs.toEqualArea({'ddr': d.structure_ddr, 'dip': d.structure_dip}).x) })
    .attr('cy', function(d) { return yScale(cnijs.toEqualArea({'ddr': d.structure_ddr, 'dip': d.structure_dip}).y) })
    .attr('r', '2')
    .attr('fill', settings.color)
    .attr('stroke', settings.color)
    .attr('id', settings.id)
}