# Axis

### Axis Types

#### Scalar Axis

#### DateTime Axis

#### Categorical Axis

### Axis Scales

Axis scales are only available to scalar axis.

#### Identity Scale (default)

#### Log Scale

#### Exponential Scale

#### Custom Scale

### Tick Locators

A tick locator determines major ticks, minor ticks, and tick labels, and "nice numbers".

#### Wilkinson

#### Talbot

An extension of Wilkinson algorithm. It is described in "An Extension of Wilkinson’s Algorithm for Positioning Tick Labels on Axes".

#### Cryptowatch

A 2-level datetime axis motivated by Cryptowatch. This design reduces the amount of label text, making a clean look without losing the required level of details.

The below is an example of typical datetime labeling. "2020-05-" is unnecessarily repeated and the label space is dense. If there were more ticks, we would have overlapping labels or would have to skip some labels.

On the other hand, 2-level layout has 2 rows of labels. The less important unit (2022-04-xx) is extracted out to the second level. The interval of the first level (5 hours) is determined from the current zoom state, label density, and datetime resolution.

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