This section describes how to create radar charts using the Image-Chart API.
In a radar chart, data points are drawn evenly spaced, clockwise around the chart. The value of the point is represented as the distance from the center of the chart, where the center represents the minimum value, and the chart edge is the maximum value. Each series is drawn as one complete circuit of the chart.
So, a radar chart is essentially a line chart wrapped into a circle, where the y-axis goes from the center of the chart to the perimeter, and the x-axis is the perimeter of the chart, starting and ending at the 12:00 line.
A chart is divided evenly into equal segments; the number of segments is the greater of these two values:
- the number of labels + 1 (as specified by
chxl, if present)
- the number of data values
For instance, a chart with 8 data points and no labels will have its data points spaced
45 degrees apart (
360 / 8 = 45).
A radar chart can support multiple series. Each series is a line in the chart.
A radar chart where the first and last point of each series is the same:
cht=r chxt=r chd=t:81,65,50,67,59,81|77,67,10,79,65,77
A radar chart where the first and last point of each series is not the same:
cht=r chxt=r chd=t:81,65,50,67,59|77,67,10,79,65
Unlike in Google Image Charts, Image-Charts will always connect series points even if first and last point of a series are different so you won't have
Optionally specify the colors of the lines using the
<color>Specify one or more line colors in RRGGBB[AA] hexadecimal format separated by commas. If there are more lines than colors, the extra lines will cycle through the color list from the beginning.