An item chart in Highcharts is a series type where the values are represented as individual dots or symbols, so that for example a quantity of ten is represented by ten dots. This is similar to a dot chart, except that in the dot chart, the items are rendered on X and Y axis, while in the item chart, they are laid out sequentially.
The item chart is used for infographics, typically for a low number of individual items within a low number of groups. The most common use case is a parliament, and other use cases may be the distribution of a feature within a group of persons, or percentages represented by a count rather than a scalar value.
Item charts can be laid out either as a rectangle or a circle. The circular layout is enabled by setting a startAngle and an endAngle. To achieve the typical parliament hemisphere, set the
startAngle to -100 and the
endAngle to 100. Then, as the default center is in the middle of the plot area and the default size is that the full circle will fill out the plot area, we can adjust the
center. These options provide a reasonable fit for the parliament:
// Circular optionscenter: ['50%', '88%'],size: '170%',startAngle: -100,endAngle: 100
Also part of the circular layout is the innerSize and rows settings. If the
innerSize is 0, the circle will be filled with dots, while in the typical parliament view we would like the center of the semi-circle to be clear. So the default
innerSize is 40%. In some cases we also want to set a fixed number of rows in order to reflect the real-world parliament. In this case we can set the
rows option, which will take precedence over the
When the angles are not given, the layout will be rectangular, and the layout option can be set either to
For the full set of available options, see the API.