Linear Radial Axis

The linear scale is used to chart numerical data. As the name suggests, linear interpolation is used to determine where a value lies in relation the center of the axis.

The following additional configuration options are provided by the radial linear scale.

Configuration Options

The axis has configuration properties for ticks, angle lines (line that appear in a radar chart outward from the center), pointLabels (labels around the edge in a radar chart). The following sections define each of the properties in those sections.

Tick Options

The following options are provided by the linear scale. They are all located in the ticks sub options. The common tick configuration options are supported by this axis.

Axis Range Settings

Given the number of axis range settings, it is important to understand how they all interact with each other.

The suggestedMax and suggestedMin settings only change the data values that are used to scale the axis. These are useful for extending the range of the axis while maintaining the auto fit behaviour.

let minDataValue = Math.min(mostNegativeValue, options.ticks.suggestedMin);
let maxDataValue = Math.max(mostPositiveValue, options.ticks.suggestedMax);

In this example, the largest positive value is 50, but the data maximum is expanded out to 100. However, because the lowest data value is below the suggestedMin setting, it is ignored.

let chart = new Chart(ctx, {
    type: 'radar',
    data: {
        datasets: [{
            label: 'First dataset',
            data: [0, 20, 40, 50]
        }],
        labels: ['January', 'February', 'March', 'April']
    },
    options: {
        scale: {
            ticks: {
                suggestedMin: 50,
                suggestedMax: 100
            }
        }
    }
});

In contrast to the suggested* settings, the min and max settings set explicit ends to the axes. When these are set, some data points may not be visible.

Step Size

If set, the scale ticks will be enumerated by multiple of stepSize, having one tick per increment. If not set, the ticks are labeled automatically using the nice numbers algorithm.

This example sets up a chart with a y axis that creates ticks at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5.

let options = {
    scale: {
        ticks: {
            max: 5,
            min: 0,
            stepSize: 0.5
        }
    }
};

Angle Line Options

The following options are used to configure angled lines that radiate from the center of the chart to the point labels. They can be found in the angleLines sub options.

Point Label Options

The following options are used to configure the point labels that are shown on the perimeter of the scale. They can be found in the pointLabels sub options.