R/utilities.R

######################################################################
## These functions are minor modifications or directly
#   copied from the
## glmnet package:
## Jerome Friedman, Trevor Hastie, Robert Tibshirani
#   (2010).
## Regularization Paths for Generalized Linear Models via
#   Coordinate Descent.
##        Journal of Statistical Software, 33(1), 1-22.
##        URL http://www.jstatsoft.org/v33/i01/.
## The reason they are copied here is because they are
#   internal functions
## and hence are not exported into the global environment.
## The original comments and header are preserved.


err <- function(n, maxit, pmax) {
    if (n == 0) 
        msg <- ""
    if (n > 0) {
        if (n < 7777) 
            msg <- "Memory allocation error"
        if (n == 7777) 
            msg <- "All used predictors have zero variance"
        if (n == 10000) 
            msg <- "All penalty factors are <= 0"
        n <- 1
        msg <- paste("in gcdnet fortran code -", msg)
    }
    if (n < 0) {
        if (n > -10000) 
            msg <- paste("Convergence for ", -n, "th lambda value not reached after maxit=", 
                maxit, " iterations; solutions for larger lambdas returned", 
                sep = "")
        if (n < -10000) 
            msg <- paste("Number of nonzero coefficients along the path exceeds pmax=", 
                pmax, " at ", -n - 10000, "th lambda value; solutions for larger lambdas returned", 
                sep = "")
        n <- -1
        msg <- paste("from gcdnet fortran code -", msg)
    }
    list(n = n, msg = msg)
}



error.bars <- function(x, upper, lower, width = 0.02, 
    ...) {
    xlim <- range(x)
    barw <- diff(xlim) * width
    segments(x, upper, x, lower, ...)
    segments(x - barw, upper, x + barw, upper, ...)
    segments(x - barw, lower, x + barw, lower, ...)
    range(upper, lower)
}


getmin <- function(lambda, cvm, cvsd) {
    cvmin <- min(cvm)
    idmin <- cvm <= cvmin
    lambda.min <- max(lambda[idmin])
    idmin <- match(lambda.min, lambda)
    semin <- (cvm + cvsd)[idmin]
    idmin <- cvm <= semin
    # cat('\n\nidmin\n\n',idmin)
    # cat('\n\nlambda[idmin]\n\n',lambda[idmin])
    # cat('\n\nmax\n\n',max(lambda[idmin]))
    lambda.1se <- max(lambda[idmin])
    list(lambda.min = lambda.min, lambda.1se = lambda.1se)
}


getoutput <- function(fit, maxit, pmax, nvars, vnames) {
    nalam <- fit$nalam
    nbeta <- fit$nbeta[seq(nalam)]
    nbetamax <- max(nbeta)
    lam <- fit$alam[seq(nalam)]
    stepnames <- paste("s", seq(nalam) - 1, sep = "")
    errmsg <- err(fit$jerr, maxit, pmax)
    switch(paste(errmsg$n), `1` = stop(errmsg$msg, call. = FALSE), 
        `-1` = print(errmsg$msg, call. = FALSE))
    dd <- c(nvars, nalam)
    if (nbetamax > 0) {
        beta <- matrix(fit$beta[seq(pmax * nalam)], pmax, nalam)[seq(nbetamax), 
            , drop = FALSE]
        df <- apply(abs(beta) > 0, 2, sum)
        ja <- fit$ibeta[seq(nbetamax)]
        oja <- order(ja)
        ja <- rep(ja[oja], nalam)
        ibeta <- cumsum(c(1, rep(nbetamax, nalam)))
        beta <- new("dgCMatrix", Dim = dd, Dimnames = list(vnames, 
            stepnames), x = as.vector(beta[oja, ]), p = as.integer(ibeta - 
            1), i = as.integer(ja - 1))
    } else {
        beta <- zeromat(nvars, nalam, vnames, stepnames)
        df <- rep(0, nalam)
    }
    b0 <- fit$b0
    if (!is.null(b0)) {
        b0 <- b0[seq(nalam)]
        names(b0) <- stepnames
    }
    list(b0 = b0, beta = beta, df = df, dim = dd, lambda = lam)
}



lambda.interp <- function(lambda, s) {
    ### lambda is the index sequence that is produced by the
    #   model
    ### s is the new vector at which evaluations are required.
    ### the value is a vector of left and right indices, and a
    #   vector of fractions.
    ### the new values are interpolated bewteen the two using
    #   the
    #   fraction
    ### Note: lambda decreases. you take:
    ### sfrac*left+(1-sfrac*right)
    if (length(lambda) == 1) {
        nums <- length(s)
        left <- rep(1, nums)
        right <- left
        sfrac <- rep(1, nums)
    } else {
        s[s > max(lambda)] <- max(lambda)
        s[s < min(lambda)] <- min(lambda)
        k <- length(lambda)
        sfrac <- (lambda[1] - s)/(lambda[1] - lambda[k])
        lambda <- (lambda[1] - lambda)/(lambda[1] - lambda[k])
        coord <- approx(lambda, seq(lambda), sfrac)$y
        left <- floor(coord)
        right <- ceiling(coord)
        sfrac <- (sfrac - lambda[right])/(lambda[left] - lambda[right])
        sfrac[left == right] <- 1
    }
    list(left = left, right = right, frac = sfrac)
}


lamfix <- function(lam) {
    llam <- log(lam)
    lam[1] <- exp(2 * llam[2] - llam[3])
    lam
}


nonzero <- function(beta, bystep = FALSE) {
    ns <- ncol(beta)
    ##beta should be in 'dgCMatrix' format
    if (nrow(beta) == 1) {
        if (bystep) 
            apply(beta, 2, function(x) if (abs(x) > 0) 
                1 else NULL) else {
            if (any(abs(beta) > 0)) 
                1 else NULL
        }
    } else {
        beta <- t(beta)
        which <- diff(beta@p)
        which <- seq(which)[which > 0]
        if (bystep) {
            nzel <- function(x, which) if (any(x)) 
                which[x] else NULL
            beta <- abs(as.matrix(beta[, which])) > 0
            if (ns == 1) 
                apply(beta, 2, nzel, which) else apply(beta, 1, nzel, which)
        } else which
    }
}



zeromat <- function(nvars, nalam, vnames, stepnames) {
    ca <- rep(0, nalam)
    ia <- seq(nalam + 1)
    ja <- rep(1, nalam)
    dd <- c(nvars, nalam)
    new("dgCMatrix", Dim = dd, Dimnames = list(vnames, stepnames), 
        x = as.vector(ca), p = as.integer(ia - 1), i = as.integer(ja - 
            1))
} 

Try the gcdnet package in your browser

Any scripts or data that you put into this service are public.

gcdnet documentation built on May 2, 2019, 5:42 a.m.