Scales
###############

format::

    chart.scale(variable,type,min,max,values,range,tickCount,formatter,tickMethod,alias,nice)

variables are optional.


e.g. ::

    chart = G2.Chart(height=500, width=1000)
    chart.data(df)
    chart.point().position('wt*mpg')
    chart.scale('wt',type='pow',exponent=3)
    chart.scale('mpg',type = 'log', base=2, min=4)
    chart.render()

Output:

.. image:: scale.png


There are several types. These type requires additional **optional** arguments.


types:

    cat: classification metric

    timeCat: time classification metrics

    linear: linear metric

    time: continuous time measurement

    log: log metrics

    pow: pow measure

    quantize: segmentation metric, user can specify uneven segmentation

    quantile: equal measure, automatically calculate the segment according to the distribution of data

    identity: constant measure


There are suitable defaults according to the nature of data if you do not specify manually.

    alias: string , name of the axis

    values: domain 

    range: [min,max]

    formatter: a javascript function definition as a string

    tickCount: number of ticks

    tickMethod: a javascript function definition as a string to calculate ticks.

    nice: 'true'/'false' nice numbers

**additional:**

    base: base for type ``log``

    exponent: exponent for typ ``pow``

    ticks: list of values for ticks in ``quantize``