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package spark.util
class Vector(val elements: Array[Double]) extends Serializable {
def length = elements.length
def apply(index: Int) = elements(index)
def + (other: Vector): Vector = {
if (length != other.length)
throw new IllegalArgumentException("Vectors of different length")
return Vector(length, i => this(i) + other(i))
}
def - (other: Vector): Vector = {
if (length != other.length)
throw new IllegalArgumentException("Vectors of different length")
return Vector(length, i => this(i) - other(i))
}
def dot(other: Vector): Double = {
if (length != other.length)
throw new IllegalArgumentException("Vectors of different length")
var ans = 0.0
var i = 0
while (i < length) {
ans += this(i) * other(i)
i += 1
}
return ans
}
/**
* return (this + plus) dot other, but without creating any intermediate storage
* @param plus
* @param other
* @return
*/
def plusDot(plus: Vector, other: Vector): Double = {
if (length != other.length)
throw new IllegalArgumentException("Vectors of different length")
if (length != plus.length)
throw new IllegalArgumentException("Vectors of different length")
var ans = 0.0
var i = 0
while (i < length) {
ans += (this(i) + plus(i)) * other(i)
i += 1
}
return ans
}
def +=(other: Vector) {
if (length != other.length)
throw new IllegalArgumentException("Vectors of different length")
var ans = 0.0
var i = 0
while (i < length) {
elements(i) += other(i)
i += 1
}
}
def * (scale: Double): Vector = Vector(length, i => this(i) * scale)
def / (d: Double): Vector = this * (1 / d)
def unary_- = this * -1
def sum = elements.reduceLeft(_ + _)
def squaredDist(other: Vector): Double = {
var ans = 0.0
var i = 0
while (i < length) {
ans += (this(i) - other(i)) * (this(i) - other(i))
i += 1
}
return ans
}
def dist(other: Vector): Double = math.sqrt(squaredDist(other))
override def toString = elements.mkString("(", ", ", ")")
}
object Vector {
def apply(elements: Array[Double]) = new Vector(elements)
def apply(elements: Double*) = new Vector(elements.toArray)
def apply(length: Int, initializer: Int => Double): Vector = {
val elements = new Array[Double](length)
for (i <- 0 until length)
elements(i) = initializer(i)
return new Vector(elements)
}
def zeros(length: Int) = new Vector(new Array[Double](length))
def ones(length: Int) = Vector(length, _ => 1)
class Multiplier(num: Double) {
def * (vec: Vector) = vec * num
}
implicit def doubleToMultiplier(num: Double) = new Multiplier(num)
implicit object VectorAccumParam extends spark.AccumulatorParam[Vector] {
def addInPlace(t1: Vector, t2: Vector) = t1 + t2
def zero(initialValue: Vector) = Vector.zeros(initialValue.length)
}
}
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