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Aperture version 1.0
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Class aperture.MapKey

A MapKey object maps from a Range object, representing a variable in data, to a color or numeric visual property such as a size or coordinate. MapKey is abstract. Instances are constructed by calling range.mappedTo(), and are used by mappings.

Method Summary

Method Detail

  • {aperture.Range} from()
    Returns the Range object that this maps from.
  • {String} label(value)
    A label for this map key reflecting the data property being mapped in readable form. This value is initialized from the label in the range but may be subsequently changed here.
    {String} value
    If a parameter given, acts as a setter and sets the label.
    {String} If no parameter given, returns the MapKey's label. Otherwise sets and returns the label.
  • map(dataValue)
    Returns a visual property value mapped from a data value. This method is abstract and implemented by different types of map keys.
    the value to be mapped using the key.
    the result of the mapping.
  • {Array} to()
    Returns the set of values that this maps to.
  • {this|Function} type(type)
    This method is mostly relevant to scalar mappings, where it can be used to set a non-linear mapping function. A string can be passed indicating a standard non linear-function, or a custom function may be supplied. Standard types include 'linear' and 'area', for area based visual properties (such as a circle's radius).

    An ordinal map key returns a type of 'ordinal'.
    {String|Function} type Optional
    if setting the value, the type of mapping function which will map the progression of 0 to 1 input values to 0 to 1 output values, or a custom function.
    {this|Function} if getting the mapping function, the type or custom function, else if setting the function a reference to this is returned for convenience of chaining method calls.