96 lines
3.7 KiB
R
96 lines
3.7 KiB
R
# Generated by using Rcpp::compileAttributes() -> do not edit by hand
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# Generator token: 10BE3573-1514-4C36-9D1C-5A225CD40393
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#' Stiefel Optimization.
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#'
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#' Stiefel Optimization for \code{V} given a dataset \code{X} and responces
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#' \code{Y} for the model \deqn{Y\sim g(B'X) + \epsilon}{Y ~ g(B'X) + epsilon}
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#' to compute the matrix `B` such that \eqn{span{B} = span(V)^{\bot}}{%
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#' span(B) = orth(span(B))}.
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#'
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#' @param X data points
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#' @param Y response
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#' @param k assumed \eqn{rank(B)}
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#' @param nObs parameter for bandwidth estimation, typical value
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#' \code{nObs = nrow(X)^lambda} with \code{lambda} in the range [0.3, 0.8].
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#' @param tau Initial step size
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#' @param tol Tolerance for update error used for stopping criterion
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#' \eqn{|| V(j) V(j)' - V(j+1) V(j+1)' ||_2 < tol}{%
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#' \| V_j V_j' - V_{j+1} V_{j+1}' \|_2 < tol}.
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#' @param maxIter Upper bound of optimization iterations
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#'
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#' @return List containing the bandwidth \code{h}, optimization objective \code{V}
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#' and the matrix \code{B} estimated for the model as a orthogonal basis of the
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#' orthogonal space spaned by \code{V}.
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#'
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#' @rdname optStiefel
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#' @name optStiefel
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#' @keywords internal
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NULL
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#' Estimated bandwidth for CVE.
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#'
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#' Estimates a propper bandwidth \code{h} according
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#' \deqn{h = \chi_{p-q}^{-1}\left(\frac{nObs - 1}{n-1}\right)\frac{2 tr(\Sigma)}{p}}{%
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#' h = qchisq( (nObs - 1)/(n - 1), p - q ) 2 tr(Sigma) / p}
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#'
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#' @param X data matrix of dimension (n x p) with n data points X_i of dimension
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#' q. Therefor each row represents a datapoint of dimension p.
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#' @param k Guess for rank(B).
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#' @param nObs Ether numeric of a function. If specified as numeric value
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#' its used in the computation of the bandwidth directly. If its a function
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#' `nObs` is evaluated as \code{nObs(nrow(x))}. The default behaviou if not
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#' supplied at all is to use \code{nObs <- nrow(x)^0.5}.
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#'
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#' @seealso [qchisq()]
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#'
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#' @export
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estimateBandwidth <- function(X, k, nObs) {
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.Call('_CVE_estimateBandwidth', PACKAGE = 'CVE', X, k, nObs)
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}
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#' Random element from Stiefel Manifold `S(p, q)`.
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#'
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#' Draws an element of \eqn{S(p, q)} which is the Stiefel Manifold.
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#' This is done by taking the Q-component of the QR decomposition
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#' from a `(p, q)` Matrix with independent standart normal entries.
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#' As a semi-orthogonal Matrix the result `V` satisfies \eqn{V'V = I_q}.
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#'
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#' @param p Row dimension
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#' @param q Column dimension
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#'
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#' @return Matrix of dim `(p, q)`.
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#'
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#' @seealso <https://en.wikipedia.org/wiki/Stiefel_manifold>
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#'
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#' @export
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rStiefel <- function(p, q) {
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.Call('_CVE_rStiefel', PACKAGE = 'CVE', p, q)
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}
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#' Conditional Variance Estimation (CVE) method.
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#'
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#' This version uses a "simple" stiefel optimization schema.
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#'
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#' @param X data points
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#' @param Y response
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#' @param k assumed \eqn{rank(B)}
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#' @param nObs parameter for bandwidth estimation, typical value
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#' \code{nObs = nrow(X)^lambda} with \code{lambda} in the range [0.3, 0.8].
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#' @param tau Initial step size (default 1)
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#' @param tol Tolerance for update error used for stopping criterion (default 1e-5)
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#' @param slack Ratio of small negative error allowed in loss optimization (default -1e-10)
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#' @param maxIter Upper bound of optimization iterations (default 50)
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#' @param attempts Number of tryes with new random optimization starting points (default 10)
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#'
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#' @return List containing the bandwidth \code{h}, optimization objective \code{V}
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#' and the matrix \code{B} estimated for the model as a orthogonal basis of the
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#' orthogonal space spaned by \code{V}.
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#'
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#' @rdname cve_cpp_V1
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#' @export
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cve_cpp <- function(X, Y, k, nObs, tauInitial = 1., tol = 1e-5, slack = -1e-10, maxIter = 50L, attempts = 10L) {
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.Call('_CVE_cve_cpp', PACKAGE = 'CVE', X, Y, k, nObs, tauInitial, tol, slack, maxIter, attempts)
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}
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