changeData(_this) {
            this.animation = true
            // remove the old bars
            _this.focus.selectAll("*")
                 //  .transition()
                 //  .duration(300)
                 //  .attr("y", 0)
                 // .style("fill-opacity", 1e-6)
                  .remove();

            // redraw the chart
            _this.draw();

            // move the chart to the previous zoomed state
            if (_this.lastTransform != null) _this.zoomed(_this);

    }