Cartesian Axes

Axes that follow a cartesian grid are known as ‘Cartesian Axes’. Cartesian axes are used for line, bar, and bubble charts. Four cartesian axes are included in Chart.js by default.

• linear
• logarithmic
• category
• time
• timeseries

Visual Components

A cartesian axis is composed of visual components that can be individually configured. These components are:

• border
• grid lines
• tick
• tick mark
• title

Border

The axis border is drawn at the edge of the axis, beside the chart area. In the image below, it is drawn in red.

config setup

const config = {
  type: 'line',
  data,
  options: {
    scales: {
      x: {
        grid: {
          borderColor: 'red'
        }
      }
    }
  }
};

const labels = Utils.months({count: 7});
const data = {
  labels: labels,
  datasets: [{
    label: 'My First dataset',
    backgroundColor: 'rgba(54, 162, 235, 0.5)',
    borderColor: 'rgb(54, 162, 235)',
    borderWidth: 1,
    data: [10, 20, 30, 40, 50, 0, 5],
  }]
};

Grid lines

The grid lines for an axis are drawn on the chart area. In the image below, they are red.

config setup

const config = {
  type: 'line',
  data,
  options: {
    scales: {
      x: {
        grid: {
          color: 'red',
          borderColor: 'grey',
          tickColor: 'grey'
        }
      }
    }
  }
};

const labels = Utils.months({count: 7});
const data = {
  labels: labels,
  datasets: [{
    label: 'My First dataset',
    backgroundColor: 'rgba(54, 162, 235, 0.5)',
    borderColor: 'rgb(54, 162, 235)',
    borderWidth: 1,
    data: [10, 20, 30, 40, 50, 0, 5],
  }]
};

Ticks and Tick Marks

Ticks represent data values on the axis that appear as labels. The tick mark is the extension of the grid line from the axis border to the label. In this example, the tick mark is drawn in red while the tick label is drawn in blue.

config setup

const config = {
  type: 'line',
  data,
  options: {
    scales: {
      x: {
        grid: {
          tickColor: 'red'
        },
        ticks: {
          color: 'blue',
        }
      }
    }
  }
};

const labels = Utils.months({count: 7});
const data = {
  labels: labels,
  datasets: [{
    label: 'My First dataset',
    backgroundColor: 'rgba(54, 162, 235, 0.5)',
    borderColor: 'rgb(54, 162, 235)',
    borderWidth: 1,
    data: [10, 20, 30, 40, 50, 0, 5],
  }]
};

Title

The title component of the axis is used to label the data. In the example below, it is shown in red.

config setup

const config = {
  type: 'line',
  data,
  options: {
    scales: {
      x: {
        title: {
          color: 'red',
          display: true,
          text: 'Month'
        }
      }
    }
  }
};

const labels = Utils.months({count: 7});
const data = {
  labels: labels,
  datasets: [{
    label: 'My First dataset',
    backgroundColor: 'rgba(54, 162, 235, 0.5)',
    borderColor: 'rgb(54, 162, 235)',
    borderWidth: 1,
    data: [10, 20, 30, 40, 50, 0, 5],
  }]
};

Common Configuration

Common options to all cartesian axes

Namespace: options.scales[scaleId]

Common options to all axes

Namespace: options.scales[scaleId]

Axis Position

An axis can either be positioned at the edge of the chart, at the center of the chart area, or dynamically with respect to a data value.

To position the axis at the edge of the chart, set the position option to one of: 'top', 'left', 'bottom', 'right'. To position the axis at the center of the chart area, set the position option to 'center'. In this mode, either the axis option is specified or the axis ID starts with the letter ‘x’ or ‘y’. To position the axis with respect to a data value, set the position option to an object such as:

{
    x: -20
}

This will position the axis at a value of -20 on the axis with ID “x”. For cartesian axes, only 1 axis may be specified.

Scale Bounds

The bounds property controls the scale boundary strategy (bypassed by min/max options).

• 'data': makes sure data are fully visible, labels outside are removed
• 'ticks': makes sure ticks are fully visible, data outside are truncated

Tick Configuration

Common tick options to all cartesian axes

Namespace: options.scales[scaleId].ticks

Common tick options to all axes

Namespace: options.scales[scaleId].ticks

Tick Alignment

The alignment of ticks is primarily controlled using two settings on the tick configuration object: align and crossAlign. The align setting configures how labels align with the tick mark along the axis direction (i.e. horizontal for a horizontal axis and vertical for a vertical axis). The crossAlign setting configures how labels align with the tick mark in the perpendicular direction (i.e. vertical for a horizontal axis and horizontal for a vertical axis). In the example below, the crossAlign setting is used to left align the labels on the Y axis.

config setup

const config = {
  type: 'bar',
  data,
  options: {
    indexAxis: 'y',
    scales: {
      y: {
        ticks: {
          crossAlign: 'far',
        }
      }
    }
  }
};

const labels = Utils.months({count: 7});
const data = {
  labels: labels,
  datasets: [{
    label: 'My First dataset',
    backgroundColor: [
      'rgba(255, 99, 132, 0.2)',
      'rgba(255, 159, 64, 0.2)',
      'rgba(255, 205, 86, 0.2)',
      'rgba(75, 192, 192, 0.2)',
      'rgba(54, 162, 235, 0.2)',
      'rgba(153, 102, 255, 0.2)',
      'rgba(201, 203, 207, 0.2)'
    ],
    borderColor: [
      'rgb(255, 99, 132)',
      'rgb(255, 159, 64)',
      'rgb(255, 205, 86)',
      'rgb(75, 192, 192)',
      'rgb(54, 162, 235)',
      'rgb(153, 102, 255)',
      'rgb(201, 203, 207)'
    ],
    borderWidth: 1,
    data: [65, 59, 80, 81, 56, 55, 40],
  }]
};

Note

The crossAlign setting is only effective when these preconditions are met:

• tick rotation is 0
• axis position is 'top', ‘left', 'bottom' or 'right'

Axis ID

The properties dataset.xAxisID or dataset.yAxisID have to match to scales property. This is especially needed if multi-axes charts are used.

var myChart = new Chart(ctx, {
    type: 'line',
    data: {
        datasets: [{
            // This dataset appears on the first axis
            yAxisID: 'first-y-axis'
        }, {
            // This dataset appears on the second axis
            yAxisID: 'second-y-axis'
        }]
    },
    options: {
        scales: {
            'first-y-axis': {
                type: 'linear'
            },
            'second-y-axis': {
                type: 'linear'
            }]
        }
    }
});

Creating Multiple Axes

With cartesian axes, it is possible to create multiple X and Y axes. To do so, you can add multiple configuration objects to the xAxes and yAxes properties. When adding new axes, it is important to ensure that you specify the type of the new axes as default types are not used in this case.

In the example below, we are creating two Y axes. We then use the yAxisID property to map the datasets to their correct axes.

var myChart = new Chart(ctx, {
    type: 'line',
    data: {
        datasets: [{
            data: [20, 50, 100, 75, 25, 0],
            label: 'Left dataset',
            // This binds the dataset to the left y axis
            yAxisID: 'left-y-axis'
        }, {
            data: [0.1, 0.5, 1.0, 2.0, 1.5, 0],
            label: 'Right dataset',
            // This binds the dataset to the right y axis
            yAxisID: 'right-y-axis'
        }],
        labels: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun']
    },
    options: {
        scales: {
            'left-y-axis': {
                type: 'linear',
                position: 'left'
            },
            'right-y-axis': {
                type: 'linear',
                position: 'right'
            }]
        }
    }
});