Classic Gauge

Chart Tutorials  

Classic Gauge

Gauge type specific features.

🔗Introduction

The gauges are represented by series where each point of the series represents a gauge needle. The point marker.length values represent the needle lengths.

Multiple series can also be combined into a single gauge where each needle is represented by the sum of a series y values. In such a case, the series default point can be used to define the marker.length value indicating needle length.

🔗Single Gauge

A single gauge chart is achieved by setting the chart config type property to 'gauge' defined by the chartType enum.

{
  type: "gauge";
}

When the chart has only one series, each point of that series is shown as a gauge needle.

When the chart has multiple series, the sum of each series y values is represented by a needle.

🔗Multiple Gauges

Multiple gauge charts are achieved by setting the chart config defaultSeries type property to 'gauge' defined by the chartType enum.

{
  defaultSeries_type: "gauge";
}

🔗Axis Settings

🔗Single Gauge Axes

In a single gauge chart, the main chart config property chart.yAxis defines the gauge axis settings.

The following code specifies scale ranges for the y axis on the gauge chart.

{
  /*Single Gauge Chart*/
  type: "gauge",
  yAxis: {
    scale_range: [0, 100]
  }
}

🔗Multiple Gauge Axes

Each gauge can have its own y axis. However, if an axis is not specified for the series, the main axis or the first axis in the yAxis array is used.

{
  defaultSeries_type: "gauge",
  yAxis: [
    {
      scaleRange: [0, 80],
      defaultTick_label_color: "orange"
    },
    {
      id: "y2",
      scaleRange: [0, 200],
      defaultTick_label_color: "blue"
    }
  ],
  series: [
    {
      points: [
        {
          y: 65,
          z: 0.8
        }
      ]
    },
    {
      yAxis: "y2",
      points: [
        {
          y: 45,
          z: 0.8
        }
      ]
    }
  ]
}

The above code creates the following multiple gauge chart.

Figure 1.
Multiple gauges using different axes.

🔗Axis Markers

🔗Needle Length

The marker.length value specifies the needle length. The value must be between 0 and 1 where 0 has no length, and 1 is the max possible needle length.

If the value is not specified the needle lengths default to .8.

Setting a start and end value such as [.2,.9] is also supported.

The following code and image demonstrate the needle length behaviors:

{
  type: "gauge",
  yAxis_scale_range: [0, 80],
  series: [
    {
      palette: "default",
      points: [
        {
          y: 40,
          marker_length: 0.2
        },
        {
          y: 45,
          marker_length: 0.5
        },
        {
          y: 50,
          marker_length: 1
        }
      ]
    }
  ]
}
Figure 2.
Gauge with needles of varying lengths

🔗Styling

🔗Angles And Arcs

Starting and ending angles can be used together to define the gauge arcs as with the following example.

{
  defaultSeries_angle: {
    start: 80,
    end: 100
  }
}

The angleArc object also provides properties for orientation and sweep. Orientation is the center angle between start and end angles.

The following has the same effect as the above start and end angle settings, however, it is given in orientation and sweep which makes it easier to think about.

{
  defaultSeries_angle: {
    orientation: 90,
    sweep: 20
  }
}

Sweep can be given in numeric degrees or as a percentage string such as '50%' which is equivalent to 180 degrees.

With gauge charts, using orientation and sweep may be the most convenient approach.

🔗Clipping

Gauges utilize a clipping algorithm to maximize gauge sizes. The following sample illustrates clipping of different arc sweeps.

{
  defaultSeries_type: "gauge",
  series: [
    {
      points: [
        {
          y: 65
        }
      ]
    },
    {
      angle_sweep: 180,
      points: [
        {
          y: 45
        }
      ]
    },
    {
      angle_sweep: 100,
      points: [
        {
          y: 45
        }
      ]
    }
  ]
}

Figure 3.
Default gauge clipping and scaling.

This clipping behavior is the default but can be disabled to produce a standard circular gauge despite the gauge arcs. This option is defined within the chart type enum chain.

{
  defaultSeries_type: "gaugeCircle"
}
Figure 4.
Gauges with no clipping.

🔗Backgrounds

The series shape property allows setting the fill of the individual gauges the series is plotted on.

The following example shows how to specify the background shading of 3 different gauges.

{
  series: [
    {
      shape_fill: "#fff0f0"
    },
    {
      shape_fill: "#f0fff1"
    },
    {
      shape_fill: ["#a0f1ff", "white", 45]
    }
  ];
}
Figure 5.
Gauges with different backgrounds.

🔗Layout

🔗Scaling

Depending on gauge arc angles, gauges are overall smaller in size than they would be as a full circle. JSC scales these up to match the width or height of all other gauges as seen in figure 3.

🔗Default Layout

Gauge layout uses an algorithm that determines the most efficient number of columns and rows to maximize gauge sizes.

🔗Padding Gauges

In cases where gauges or other similar series are too crowded, a general padding value can be applied for all gauges on the chart.

{
  defaultSeries: {
    shape_padding: 0.2;
  }
}

🔗