text: export function initControlLabels() {
      const chart = this;
      const config = this.config;
  
      //Add settings label
      const first_setting = this.controls.wrap
          .selectAll('div.control-group')
          .filter(f => f.type != 'subsetter')
          .filter(f => f.option != 'r_ratio[0]')
          .filter((f, i) => i == 0)
          .attr('class', 'first-setting');
  
      this.controls.setting_header = this.controls.wrap
          .insert('div', '.first-setting')
          .attr('class', 'subtitle')
          .style('border-top', '1px solid black')
          .style('border-bottom', '1px solid black')
          .style('margin-right', '1em')
          .style('margin-bottom', '1em');
  
      this.controls.setting_header
          .append('span')
          .text('Settings')
          .style('font-weight', 'strong')
          .style('display', 'block');
  
      //Add filter label if at least 1 filter exists
      if (config.r_ratio_filter || config.filters.length > 0) {
          //insert a header before the first filter
          const control_wraps = this.controls.wrap
              .selectAll('div')
              .filter(
                  controlInput =>
                      controlInput.label === 'R Ratio Range' || controlInput.type === 'subsetter'
              )
              .classed('subsetter', true);
  
          this.controls.filter_header = this.controls.wrap
              .insert('div', 'div.subsetter')
              .attr('class', 'subtitle')
              .style('border-top', '1px solid black')
              .style('border-bottom', '1px solid black')
              .style('margin-right', '1em')
              .style('margin-bottom', '1em');
          this.controls.filter_header
              .append('span')
              .text('Filters')
              .style('font-weight', 'strong')
              .style('display', 'block');
          const population = d3.set(this.initial_data.map(m => m[config.id_col])).values().length;
          this.controls.filter_header
              .append('span')
              .attr('class', 'popCount')
              .html(
                  '<span class="numerator">' +
                      population +
                      '</span> of <span class="denominator">' +
                      population +
                      '</span> participants shown.'
              )
              .style('font-size', '0.8em');
  
          this.controls.filter_numerator = this.controls.filter_header
              .select('span.popCount')
              .select('span.numerator');
          this.controls.filter_denominator = this.controls.filter_header
              .select('span.popCount')
              .select('span.denominator');
      }
  }
  