if (indepType == 'date' || indepType == 'datetime') {
        this.attrs_.xValueParser = Dygraph.dateParser;
        this.attrs_.axes.x.valueFormatter = Dygraph.dateString_;
        this.attrs_.axes.x.ticker = Dygraph.dateTicker;
        this.attrs_.axes.x.axisLabelFormatter = Dygraph.dateAxisFormatter;