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/**
* Returns a root scale for the specified domain. The arguments to this
* constructor are optional, and equivalent to calling {@link #domain}.
* The default domain and range are [0,1].
*
* @class Represents a root scale; a function that performs a power
* transformation. <style type="text/css">sub{line-height:0}</style> Most
* commonly, a root scale represents a 1-dimensional root transformation from a
* numeric domain of input data [<i>d<sub>0</sub></i>, <i>d<sub>1</sub></i>] to
* a numeric range of pixels [<i>r<sub>0</sub></i>, <i>r<sub>1</sub></i>].
*
* <p>Note that the scale is itself a function, and thus can be used as a
* property directly, assuming that the data associated with a mark is a
* number. While this is convenient for single-use scales, frequently it is
* desirable to define scales globally:
*
* <pre>var y = pv.Scale.root(0, 100).range(0, 640);</pre>
*
* The <tt>y</tt> scale can now be equivalently referenced within a property:
*
* <pre> .height(function(d) y(d))</pre>
*
* Alternatively, if the data are not simple numbers, the appropriate value can
* be passed to the <tt>y</tt> scale (e.g., <tt>d.foo</tt>). The {@link #by}
* method similarly allows the data to be mapped to a numeric value before
* performing the root transformation.
*
* @param {number...} domain... optional domain values.
* @extends pv.Scale.quantitative
*/
pv.Scale.root = function() {
var scale = pv.Scale.quantitative();
/**
* Sets or gets the exponent; defaults to 2.
*
* @function
* @name pv.Scale.root.prototype.power
* @param {number} [v] the new exponent.
* @returns {pv.Scale.root} <tt>this</tt>, or the current base.
*/
scale.power = function(v) {
if (arguments.length) {
var b = Number(v), p = 1 / b;
scale.transform(
function(x) { return Math.pow(x, p); },
function(y) { return Math.pow(y, b); });
return this;
}
return b;
};
scale.domain.apply(scale, arguments);
return scale.power(2);
};
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23 entries across 23 versions & 1 rubygems