PWCEmpiricalCDF

class PWCEmpiricalCDF(breakPoints: DoubleArray, proportions: DoubleArray = DoubleArray(breakPoints.size - 1) { 1.0 / (breakPoints.size - 1) }, name: String? = null) : Distribution, ContinuousDistributionIfc, InverseCDFIfc, GetRVariableIfc

Represents a piecewise constant empirical cumulative distribution function (CDF).

This class defines a distribution based on breakpoints and proportions, where the breakpoints represent partitioned intervals of the distribution and the proportions define the probability mass assigned to each corresponding interval.

Parameters

breakPoints

Array of doubles representing the breakpoints. The array must be sorted and values must be finite. There must be at least two breakpoints, and the values must strictly increase. These define the boundaries of the distribution's intervals.

proportions

Optional array of proportions corresponding to each interval between breakpoints. The array size should be one less than the size of the breakPoints array. By default, all intervals are assigned equal portions of probability. The proportions must form a valid probability distribution and be in the range (0,1).

name

Optional name for the distribution, defaulting to null if not provided.

Throws

If the input parameters do not adhere to the necessary constraints (e.g., invalid proportions, breakpoints not sorted, etc.).

Constructors

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constructor(breakPoints: DoubleArray, proportions: DoubleArray = DoubleArray(breakPoints.size - 1) { 1.0 / (breakPoints.size - 1) }, name: String? = null)

Creates an instance of PWCEmpiricalCDF.

Properties

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open override val id: Int
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open override var label: String?
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open override val name: String

Functions

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Returns an array of probabilities each representing F(x_i). The CDF is evaluated for each point in the input array x and the probabilities are returned in the returned array.

open fun cdf(interval: Interval): Double

Returns the probability of being in the interval, F(upper limit) - F(lower limit) Be careful, this is Pr{lower limit < = X < = upper limit} which includes the lower limit and has implications if the distribution is discrete

open fun cdf(x1: Double, x2: Double): Double

Returns the Pr{x1 <= X <= x2} for the distribution. Be careful, this is Pr{x1 <= X <= x2} which includes the lower limit and has implications if the distribution is discrete

open override fun cdf(x: Double): Double

Returns the F(x) = Pr{X <= x} where F represents the cumulative distribution function

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Computes the complementary cumulative probability distribution function for given value of x. This is P{X > x}

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open override fun domain(): Interval
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open override fun instance(): PWCEmpiricalCDF
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open fun invCDF(probabilities: DoubleArray): DoubleArray

Computes x_p where P(X <= x_p) = p for the supplied array of probabilities. Requires that the values within the supplied array are in (0,1)

open override fun invCDF(p: Double): Double

Provides the inverse cumulative distribution function for the distribution

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open fun likelihood(data: DoubleArray): Double

Assuming that the observations in the array data are from a random sample, this function computes the likelihood function. This is computed using as the sum of the log-likelihood function raised to e. Implementation may want to specify other computationally efficient formulas for this function or (most likely) the sum of the log-likelihood function.

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open override fun logLikelihood(x: Double): Double

Computes the natural log of the pdf function evaluated at x. Implementations may want to specify computationally efficient formulas for this function.

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open override fun mean(): Double

Returns the mean or expected value of a distribution

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open override fun parameters(): DoubleArray
open override fun parameters(params: DoubleArray)

n = number of break points k = number of proportions k = n - 1 param0 = n param1..n param(n+1)..(n+1+k)

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open override fun pdf(x: Double): Double

Returns the f(x) where f represents the probability density function for the distribution. Note this is not a probability.

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open override fun randomVariable(streamNumber: Int, streamProvider: RNStreamProviderIfc): PWCEmpiricalRV

Promises to return a random variable that uses the supplied stream number using the supplied stream provider

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Returns the standard deviation for the distribution as the square root of the variance if it exists

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Computes the sum of the log-likelihood function evaluated at each observation in the data. Implementations may want to specify computationally efficient formulas for this function.

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open override fun toString(): String
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open override fun variance(): Double

Returns the variance of the distribution if defined