#' Estimate the normalized columns μ of the β matrix parameter in a mixture of
#' logistic regressions models, with a spectral method described in the package vignette.
#'
+#' @name computeMu
+#'
#' @param X Matrix of input data (size nxd)
#' @param Y Vector of binary outputs (size n)
#' @param optargs List of optional argument:
#' and \code{generateSampleIO} for I/O random generation.
#'
#' @examples
-#' io = generateSampleIO(10000, 1/2, matrix(c(1,0,0,1),ncol=2), c(0,0), "probit")
-#' μ = computeMu(io$X, io$Y, list(K=2)) #or just X and Y for estimated K
+#' io <- generateSampleIO(10000, 1/2, matrix(c(1,0,0,1),ncol=2), c(0,0), "probit")
+#' μ <- computeMu(io$X, io$Y, list(K=2)) #or just X and Y for estimated K
+#'
#' @export
-computeMu = function(X, Y, optargs=list())
+computeMu <- function(X, Y, optargs=list())
{
- if (!is.matrix(X) || !is.numeric(X) || any(is.na(X)))
- stop("X: real matrix, no NA")
- n = nrow(X)
- d = ncol(X)
- if (!is.numeric(Y) || length(Y)!=n || any(Y!=0 & Y!=1))
- stop("Y: vector of 0 and 1, size nrow(X), no NA")
- if (!is.list(optargs))
- stop("optargs: list")
+ if (!is.matrix(X) || !is.numeric(X) || any(is.na(X)))
+ stop("X: real matrix, no NA")
+ n <- nrow(X)
+ d <- ncol(X)
+ if (!is.numeric(Y) || length(Y)!=n || any(Y!=0 & Y!=1))
+ stop("Y: vector of 0 and 1, size nrow(X), no NA")
+ if (!is.list(optargs))
+ stop("optargs: list")
- # Step 0: Obtain the empirically estimated moments tensor, estimate also K
- M = if (is.null(optargs$M)) computeMoments(X,Y) else optargs$M
- K = optargs$K
- if (is.null(K))
- {
- # TODO: improve this basic heuristic
- Σ = svd(M[[2]])$d
- large_ratio <- ( abs(Σ[-d] / Σ[-1]) > 3 )
- K <- if (any(large_ratio)) max(2, which.min(large_ratio)) else d
- }
+ # Step 0: Obtain the empirically estimated moments tensor, estimate also K
+ M <- if (is.null(optargs$M)) computeMoments(X,Y) else optargs$M
+ K <- optargs$K
+ if (is.null(K))
+ {
+ # TODO: improve this basic heuristic
+ Σ <- svd(M[[2]])$d
+ large_ratio <- ( abs(Σ[-d] / Σ[-1]) > 3 )
+ K <- if (any(large_ratio)) max(2, which.min(large_ratio)) else d
+ }
+ else if (K > d)
+ stop("K: integer >= 2, <= d")
- # Step 1: generate a family of d matrices to joint-diagonalize to increase robustness
- d = ncol(X)
- fixed_design = FALSE
- jd_nvects = ifelse(!is.null(optargs$jd_nvects), optargs$jd_nvects, 0)
- if (jd_nvects == 0)
- {
- jd_nvects = d
- fixed_design = TRUE
- }
- M2_t = array(dim=c(d,d,jd_nvects))
- for (i in seq_len(jd_nvects))
- {
- rho = if (fixed_design) c(rep(0,i-1),1,rep(0,d-i)) else normalize( rnorm(d) )
- M2_t[,,i] = .T_I_I_w(M[[3]],rho)
- }
+ # Step 1: generate a family of d matrices to joint-diagonalize to increase robustness
+ d <- ncol(X)
+ fixed_design <- FALSE
+ jd_nvects <- ifelse(!is.null(optargs$jd_nvects), optargs$jd_nvects, 0)
+ if (jd_nvects == 0)
+ {
+ jd_nvects <- d
+ fixed_design <- TRUE
+ }
+ M2_t <- array(dim=c(d,d,jd_nvects))
+ for (i in seq_len(jd_nvects))
+ {
+ rho <- if (fixed_design) c(rep(0,i-1),1,rep(0,d-i)) else normalize( rnorm(d) )
+ M2_t[,,i] <- .T_I_I_w(M[[3]],rho)
+ }
- # Step 2: obtain factors u_i (and their inverse) from the joint diagonalisation of M2_t
- jd_method = ifelse(!is.null(optargs$jd_method), optargs$jd_method, "uwedge")
- V =
- if (jd_nvects > 1) {
- #NOTE: increasing itermax does not help to converge, thus we suppress warnings
- suppressWarnings({jd = jointDiag::ajd(M2_t, method=jd_method)})
-# if (jd_method=="uwedge") jd$B else solve(jd$A)
- if (jd_method=="uwedge") jd$B else MASS::ginv(jd$A)
- }
- else
- eigen(M2_t[,,1])$vectors
+ # Step 2: obtain factors u_i (and their inverse) from the joint diagonalisation of M2_t
+ jd_method <- ifelse(!is.null(optargs$jd_method), optargs$jd_method, "uwedge")
+ V <-
+ if (jd_nvects > 1) {
+ # NOTE: increasing itermax does not help to converge, thus we suppress warnings
+ suppressWarnings({jd = jointDiag::ajd(M2_t, method=jd_method)})
+ if (jd_method=="uwedge") jd$B else MASS::ginv(jd$A)
+ }
+ else
+ eigen(M2_t[,,1])$vectors
- # Step 3: obtain final factors from joint diagonalisation of T(I,I,u_i)
- M2_t = array(dim=c(d,d,K))
- for (i in seq_len(K))
- M2_t[,,i] = .T_I_I_w(M[[3]],V[,i])
- suppressWarnings({jd = jointDiag::ajd(M2_t, method=jd_method)})
-# U = if (jd_method=="uwedge") solve(jd$B) else jd$A
- U = if (jd_method=="uwedge") MASS::ginv(jd$B) else jd$A
- μ = normalize(U[,1:K])
+ # Step 3: obtain final factors from joint diagonalisation of T(I,I,u_i)
+ M2_t <- array(dim=c(d,d,K))
+ for (i in seq_len(K))
+ M2_t[,,i] <- .T_I_I_w(M[[3]],V[,i])
+ suppressWarnings({jd = jointDiag::ajd(M2_t, method=jd_method)})
+ U <- if (jd_method=="uwedge") MASS::ginv(jd$B) else jd$A
+ μ <- normalize(U[,1:K])
- # M1 also writes M1 = sum_k coeff_k * μ_k, where coeff_k >= 0
- # ==> search decomposition of vector M1 onto the (truncated) basis μ (of size dxK)
- # This is a linear system μ %*% C = M1 with C of size K ==> C = psinv(μ) %*% M1
- C = MASS::ginv(μ) %*% M[[1]]
- μ[,C < 0] = - μ[,C < 0]
- μ
+ # M1 also writes M1 = sum_k coeff_k * μ_k, where coeff_k >= 0
+ # ==> search decomposition of vector M1 onto the (truncated) basis μ (of size dxK)
+ # This is a linear system μ %*% C = M1 with C of size K ==> C = psinv(μ) %*% M1
+ C <- MASS::ginv(μ) %*% M[[1]]
+ μ[,C < 0] <- - μ[,C < 0]
+ μ
}