# Axes

Axes are an integral part of a chart. They are used to determine how data maps to a pixel value on the chart. In a cartesian chart, there is 1 or more X axis and 1 or more Y axis to map points onto the 2 dimensional canvas. These axes are know as 'cartesian axes'.

In a radial chart, such as a radar chart or a polar area chart, there is a single axis that maps points in the angular and radial directions. These are known as 'radial axes'.

Scales in Chart.js >V2.0 are significantly more powerful, but also different than those of v1.0.

- Multiple X & Y axes are supported.
- A built-in label auto-skip feature detects would-be overlapping ticks and labels and removes every nth label to keep things displaying normally.
- Scale titles are supported
- New scale types can be extended without writing an entirely new chart type

# Common Configuration

The following properties are common to all axes provided by Chart.js

Name | Type | Default | Description
--- | --- | --- | ---
`display` | `Boolean` | `true` | If set to `false` the axis is hidden from view. Overrides gridLines.display, scaleLabel.display, and ticks.display.
`callbacks` | `Object` |  | Callback functions to hook into the axis lifecycle. more...
`weight` | `Number` | `0` | The weight used to sort the axis. Higher weights are further away from the chart area.

## Callbacks

There are a number of config callbacks that can be used to change parameters in the scale at different points in the update process.

Name | Arguments | Description
--- | --- | ---
`beforeUpdate` | `axis` | Callback called before the update process starts.
`beforeSetDimensions` | `axis` | Callback that runs before dimensions are set.
`afterSetDimensions` | `axis` | Callback that runs after dimensions are set.
`beforeDataLimits` | `axis` | Callback that runs before data limits are determined.
`afterDataLimits` | `axis` | Callback that runs after data limits are determined.
`beforeBuildTicks` | `axis` | Callback that runs before ticks are created.
`afterBuildTicks` | `axis` | Callback that runs after ticks are created. Useful for filtering ticks.
`beforeTickToLabelConversion` | `axis` | Callback that runs before ticks are converted into strings.
`afterTickToLabelConversion` | `axis` | Callback that runs after ticks are converted into strings.
`beforeCalculateTickRotation` | `axis` | Callback that runs before tick rotation is determined.
`afterCalculateTickRotation` | `axis` | Callback that runs after tick rotation is determined.
`beforeFit` | `axis` | Callback that runs before the scale fits to the canvas.
`afterFit` | `axis` | Callback that runs after the scale fits to the canvas.
`afterUpdate` | `axis` | Callback that runs at the end of the update process.

## Updating Axis Defaults

The default configuration for a scale can be easily changed using the scale service. All you need to do is to pass in a partial configuration that will be merged with the current scale default configuration to form the new default.

For example, to set the minimum value of 0 for all linear scales, you would do the following. Any linear scales created after this time would now have a minimum of 0.

    Chart.scaleService.updateScaleDefaults('linear', {
        ticks: {
            min: 0
        }
    });

## Creating New Axes

To create a new axis, see the developer docs.

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