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package scalam
import scala.collection.generic.CanBuildFrom
/** Contains useful math functions. */
package object math {
/**
* Smooths a collection of numeric values using the moving-average algorithm.
* The algorithm takes a window of width `width` that "slides" along the whole collection.
* A new collection is created by taking the average of all points located in each window.
*
* @param collection the collection to smooth
* @param width the window's witdh
* @param passes how many times the collection is smoothed (i.e. how often smooth calls itself recursively)
* @tparam Elem the type of the elements contained in the collection
* @tparam Coll[Elem] the type of the collection to be smoothed
*/
def smooth[Elem, Coll[Elem]](collection: Coll[Elem], width: Int, passes: Int = 1)(implicit fractional: Fractional[Elem], cbf: CanBuildFrom[Coll[Elem], Elem, Coll[Elem]], view: Coll[Elem] => Seq[Elem]): Coll[Elem] = {
def average(xs: Seq[Elem]): Elem = {
import fractional._
xs.sum / fromInt(xs.length)
}
if (passes <= 0) collection
else {
val b = cbf(collection)
collection.sliding(width).foreach(neighbours => b += average(neighbours))
smooth(b.result(), width, passes - 1)
}
}
}
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