Error Bars
Error bars visualize errors, or high and low values, in statistical data. They typically represent high and low values in data, or a standard deviation, a percentile, or a quantile. The high and low values are represented as horizontal lines, or "whiskers", connected by a vertical stem.
Although error bars are technically a chart type (ChartType.ERRORBAR), you normally use them together with some primary chart type, such as a scatter or column chart.
To display the error bars for data points, you need to have a separate data series for the low and high values. The data series needs to use the PlotOptionsErrorBar plot options type.
Source code
Java
// Create a chart of some primary type
Chart chart = new Chart(ChartType.SCATTER);
// Modify the default configuration a bit
Configuration conf = chart.getConfiguration();
conf.setTitle("Average Temperatures in Turku");
conf.getLegend().setEnabled(false);
// The primary data series
ListSeries averages = new ListSeries(
-6, -6.5, -4, 3, 9, 14, 17, 16, 11, 6, 2, -2.5);
// Error bar data series with low and high values
DataSeries errors = new DataSeries();
errors.add(new DataSeriesItem(0, -9, -3));
errors.add(new DataSeriesItem(1, -10, -3));
errors.add(new DataSeriesItem(2, -8, 1));
...
// Need to be used for series to be recognized as error bar
PlotOptionsErrorbar barOptions = new PlotOptionsErrorbar();
errors.setPlotOptions(barOptions);
// The errors should be drawn lower
conf.addSeries(errors);
conf.addSeries(averages);You should add the error bar series first, to have it rendered lower in the chart.
Plot Options
Plot options for error bar charts have type PlotOptionsErrorBar. See the API documentation for details of the plot options.
|
Note
|
Although most visual styles are defined in CSS, some options, such as whiskerLength, are set through the Java API.
|