#' Calculate PLS component, orthogonalise X and remove orthogonal information
#' @description Calculate PLS component, orthogonalise X and remove orthogonal information. This function is not for general use, rather than part of the opls function.
#' @param X Input matrix with rows and columns representing observations and variables
#' @param Y Dependend variable, in form of dummy matrix (multi-levels allowed) or numeric column vector
#' @return Returned is a list with the following entries:
#' \item{Filtered X}{Orthogonal filtered X matrix.}
#' \item{Scores X pred}{PLS component scores.}
#' \item{Loadings X pred}{PLS component loadings for X.}
#' \item{Weights pred}{PLS component variable weights for X.}
#' \item{Scores X orth}{Orthogonal component scores.}
#' \item{Loaadings X orth}{Orthogonal component loadings for X.}
#' \item{Weights X orth}{Orthogonal component X variable weights.}
#' \item{Loadings Y}{PLS component Y loadings.}
#' @author Torben Kimhofer \email{tkimhofer@@gmail.com}
#' @noRd
NIPALS_OPLS_component_mulitlevel <- function(X, Y) {
if (ncol(Y) > 1) {
# 4 initialise scores u with column of Y, this is for two level outcome
W_h <- apply(Y, 2, function(i, x = X) {
(t(i) %*% x)/drop(crossprod(i))
})
ss_T <- ss_W_h <- sum(W_h^2)
# estimate PCA the principal components of W as long as the ratio of SS of current score vector t divided by SS of W is larger than given
# threshold, typicaly 10e-10
count <- 1
while ((ss_T/ss_W_h) > 1e-09) {
# print((ss_T/ss_W_h))
if (count == 1) {
w_pca <- NIPALS_PCAcomponent(W_h)
T_w <- rbind(w_pca$Scores)
} else {
w_pca <- NIPALS_PCAcomponent(w_pca$`Residual X`)
T_w <- cbind(T_w, w_pca$Scores)
}
ss_T <- sum(w_pca$Scores[, 1]^2)
count <- count + 1
if (count > 30) {
stop("endless loop?")
}
}
}
dd <- 1
count <- 1
u <- cbind(Y[, 1])
while (dd > 1e-10) {
# 1 calc weights scores and loadings
w_h <- (t(u) %*% X)/drop(crossprod(u))
# 2 normalise with norm
w_h <- t(w_h)/sqrt(sum(w_h[1, ]^2)) # normalisation
# 3 calc scores X
t_h <- (X %*% w_h)/crossprod(w_h)[1, 1]
# 4 calc loadings Y -> c is q
c_h <- (t(t_h) %*% Y)/drop(crossprod(t_h))
# 5. cal new u and compare with one in previus iteration (stop criterion)
u_new <- (Y %*% t(c_h))/drop(crossprod(t(c_h)))
if (count > 1) {
dd <- sum((u_new - u)^2)/sum(as.numeric(u_new)^2) #print(dd)
}
u <- u_new
count <- count + 1
}
# 6 calc loadings
p_h <- (t(t_h) %*% X)/drop(crossprod(t_h))
# for multicolumn Y: estimate orthogonal component
if (ncol(Y) > 1) {
# 11: orthogonalise p_h (use the PCA scores of Y weights: T_w)
for (i in 1:ncol(T_w)) {
t_w <- cbind(T_w[, i])
p_h <- p_h - ((t(t_w) %*% t(p_h)/crossprod(t_w)[1, 1]) %*% t(t_w))
}
w_o <- p_h
} else {
w_o <- p_h - ((t(w_h) %*% t(p_h)/drop(crossprod(w_h))) %*% t(w_h))
}
# 8: normalise
w_o <- w_o/sqrt(sum(w_o[1, ]^2)) # normalisation
# 9: orthogonal scores
t_o <- (X %*% t(w_o))/drop(crossprod(t(w_o)))
# 10 orthogonal laodings
p_o <- (t(t_o) %*% X)/drop(crossprod(t_o))
# 11: Filter data
E_opls <- X - (t_o %*% p_o)
# Y_res = Y - u %*% c_h 16: return paramters
res <- list(`Filtered X` = E_opls, `Scores X pred` = t_h, `Loadings X pred` = p_h, `Weights pred` = w_h, `Scores X orth` = t_o, `Loadings X orth` = p_o,
`Weights X orth` = w_o, `Loadings Y` = c_h)
return(res)
}
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