point.md

Point

Point scales are a special case of band scales that the bandwidth always fixed to zero.

Usage

import { Point, PointOptions } from '@antv/scale';

const options: PointOptions = {
  domain: ["A", "B", "C", "D"],
  padding: 0.5,
  round: true,
  range: [0, 600]
}

const x = new Point(options);

scale.map('A') // 75
scale.getStep(); // 150
scale.getBandWidth(); // always 0

Options

Key	Description	Type	Default
domain	Sets the scale’s domain to the specified array of values.	number[] | string[] | Date[]	[]
range	Sets the scale’s range to the specified array of values.	number[]	[0, 1]
unknown	Sets the output value of the scale for undefined (or NaN) input values.	any	undefined
round	If round option is truthy, the start and stop of each point will be integers.	boolean	false
padding	Set the scale's padding. In fact, this is the outerPadding of the band option. For more info about this, please see example.	number	0
align	The align option specifies how outer padding is distributed in the range, the value should in the range [0, 1]. For example, value of 0.5 means that points should be centered within the range, value of 0 or 1 may be used to shift the points to one side.	number	0.5
compare	Sets the comparator for sorting the domain before mapping.	(a: string or number, b: string or number) => number	undefined

Example

We can easily find that point scale's bandwidth is always zero.

PO = Padding = PaddingInner
domain =  ["A", "B", "C"]


|<------------------------------------------- range ------------------------------------------->|
|             |                                 |                                 |             |
|<--step*PO-->|<--------------step------------->|<--------------step------------->|<--step*PO-->|
|             |                                 |                                 |             |
|             A                                 B                                 C             |
|-----------------------------------------------------------------------------------------------|

Methods

# map(x: number | string): number

Given a value in the input domain, returns the corresponding value in the output range if it is not undefined (or NaN), otherwise options.unknown

# invert(x: number): number | string

Given a value from the range, returns the corresponding value from the domain.

# update(options: PointOptions): void

Update the scale's options and rescale.

# getOptions(): PointOptions

Returns the scale's current options.

# clone(): Point

Returns a new point scale with the independent and same options as the original one.

# getStep(): number

Returns point scale's step, for more info about this, please see example.

# getBandWidth(): number

Returns point scale's bandWidth, In fact, the value is always 0. For more info about this, please see example.

# getRange(): number[]

Returns band scale's adjusted range example.