R/rcspline.restate.s

Defines functions rcsplineFunction rcspline.restate

Documented in rcsplineFunction rcspline.restate

rcspline.restate <- function(knots, coef, type=c("ordinary","integral"),
                             x="X", lx=nchar(x),norm=2, 
                             columns=65, before="& &", after="\\", 
                             begin="", nbegin=0,
                             digits=max(8,.Options$digits))
{
  type <- match.arg(type)
  k <- length(knots)
  if(k<3)
    stop("must have >=3 knots in a restricted cubic spline")
  
  p <- length(coef)
  if(p == k)
    {
      Intc <- coef[1]
      coef <- coef[-1]
      p <- p-1
    }
  else Intc <- 0
  
  if(k-1 != p)
    stop("coef must be of length # knots - 1")

  knotnk <- knots[k]
  knotnk1 <- knots[k-1]
  knot1 <- knots[1]
  
  kd <- if(norm==0) 1 else if(norm==1)(knotnk-knotnk1)^3 else (knotnk-knot1)^2
  
  coef[-1] <- coef[-1]/kd

  d <- c(0, knots-knotnk)[1:p]
  coefk <- sum(coef*d)/(knotnk-knotnk1)

  d <- c(0, knots-knotnk1)[1:p]
  coefk1 <- sum(coef*d)/(knotnk1-knotnk)

  if(!length(names(coef)))
    names(coef) <- paste(x,1:length(coef),sep="")
  
  coef <- c(coef, coefk, coefk1)
  names(coef)[k] <- "1st restricted coef"
  names(coef)[k+1] <- "2nd restricted coef"

  if(type=="integral")
    coef <- c(.5*coef[1],.25*coef[-1])

  cof <- formatSep(coef, digits)
  kn <- formatSep(-knots, digits)
  if(Intc!=0)
    {
      txt <- txt2 <- formatSep(Intc, digits)
      if(type=="integral")
        {
          txt <- paste(txt, "* x")
          txt2 <- paste(txt2, '*', x)
        }
      
      if(coef[1]>=0)
        {
          txt <- paste(txt, "+");
          txt2 <- paste(txt2, '+')
        }
    }
  else txt <- txt2 <- ""

  if(cof[1]!=0)
    {
      txt <- paste(txt, cof[1],
                   if(type=="ordinary")"* x"
                   else "* x^2",
                   sep="")
    
      txt2 <- paste(txt2, cof[1],
                    if(type=="ordinary") paste("*",x)
                    else paste("*",x,"^2"),
                    sep="")
    }
  
  for(i in 2:(p+2))
    {
      nam <- paste("pmax(x",
                   if(knots[i-1]<0) "+"
                   else NULL, 
                   if(knots[i-1]!=0) kn[i-1]
                   else NULL,
                   ",0)^",
                   if(type=="ordinary")"3"
                   else "4",
                   sep="")
    
      nam2 <- paste("pmax(",x,
                    if(knots[i-1]<0) "+"
                    else NULL,
                    if(knots[i-1]!=0) kn[i-1]
                    else NULL,
                    ",0)^",
                    if(type=="ordinary")"3"
                    else "4",
                    sep="")
      
      z <- paste(if(coef[i]>0 & (i>2 | coef[1]!=0 | Intc!=0)) "+"
      else NULL,
                 cof[i], "*", nam, sep="")
      
      z2 <- paste(if(coef[i]>0 & (i>2 | coef[1]!=0 | Intc!=0)) "+"
      else NULL,
                  cof[i], "*", nam2, sep="")
      
      txt <- paste(txt , z,  sep="")
      txt2<- paste(txt2, z2, sep="")
    }

  func <- parse(text=paste('function(x)', txt))

  cof <- formatSep(coef, digits)
  kn <- formatSep(-knots, digits)

  lcof <- nchar(cof)
  cof <- latexSN(cof)
  
  cur <- begin; colcnt <- nbegin; tex <- NULL
  if(Intc!=0)
    {
      fint <- formatSep(Intc, digits)
      if(type=="integral")
        {
          fint <- paste(fint, x)
          colcnt <- colcnt+2
        }
    
      cur <- paste(cur, fint, sep="")
      colcnt <- colcnt + nchar(fint)
      if(coef[1]>0)
        {
          cur <- paste(cur, " + ", sep="");
          colcnt <- colcnt+3
        }
    }
  
  if(coef[1]!=0)
    {
      sp <- if(substring.location(cof[1],"times")$first > 0) "\\:"
      else NULL
    
      cur <- paste(cur, cof[1], sp, x,
                   if(type=="integral") "^2",
                   sep="")
      
      ##\:=medium space in LaTeX
      colcnt <- colcnt+lcof[1]+lx+(type=="integral")
    }

  tex.names <- character(p+2)
  size <- lx+lcof[-1]+nchar(kn)+3

  for(i in 2:(p+2))
    {
      nam <- paste("(", x,
                   if(knots[i-1]<0) "+"
                   else NULL,
                   if(knots[i-1]!=0) kn[i-1]
                   else NULL, 
                   ")_{+}^{",
                   if(type=="ordinary")"3}"
                   else "4}",
                   sep="")
      
      q <- paste(if(coef[i]>0 & (i>2 | coef[1]!=0 | Intc!=0)) "+"
      else NULL,
                 cof[i], nam, sep="")
      
      n <- size[i-1]
      if(colcnt+n > columns)
        {
          tex <- c(tex, cur)
          cur <- ""
          colcnt <- 0
        }
    
      cur <- paste(cur, q, sep="")
      colcnt <- colcnt+n
    }

  tex <- c(tex, cur)
  tex <- paste(before, tex, after)

  if(Intc!=0) coef <- c(Intercept=Intc, coef)

  attr(coef, "knots") <- knots
  attr(coef, "function") <- func
  attr(coef, "function.text") <- txt2
  attr(coef, "latex")   <- tex
  names(colcnt) <- NULL
  attr(coef, "columns.used") <- colcnt
  
  coef
}

rcsplineFunction <- function(knots, coef=numeric(0), norm=2,
                             type=c('ordinary', 'integral')) {
  type <- match.arg(type)
  k <- length(knots)
  kd <- if(norm==0) 1 else if(norm==1) knots[k]-knots[k-1] else
  (knots[k]-knots[1])^.66666666666666666666666
  
  f <- function(x, knots, coef, kd, type) {
    k       <- length(knots)
    knotnk  <- knots[k]
    knotnk1 <- knots[k - 1]
    knot1   <- knots[1]
    if(length(coef) < k) coef <- c(0, coef)
    if(type == 'ordinary') {
      y <- coef[1] + coef[2] * x
      for(j in 1 : (k - 2))
        y <- y + coef[j + 2] *
          (pmax((x - knots[j]) / kd, 0) ^ 3 +
             ((knotnk1 - knots[j]) *
                pmax((x - knotnk) / kd, 0) ^ 3 -
                  (knotnk -  knots[j]) *
                    (pmax((x - knotnk1) / kd, 0) ^ 3)) /
                      (knotnk -  knotnk1))
      return(y)
    }
    y <- coef[1] * x + 0.5 * coef[2] * x * x
    for(j in 1 : (k - 2))
      y <- y + 0.25 * coef[j + 2] * kd *
        (pmax((x - knots[j]) / kd, 0) ^ 4 +
           ((knotnk1 - knots[j]) *
              pmax((x - knotnk) / kd, 0) ^ 4 -
                (knotnk -  knots[j]) *
                  (pmax((x - knotnk1) / kd, 0) ^ 4)) /
                    (knotnk -  knotnk1))
    y
  }
  formals(f) <- list(x=numeric(0), knots=knots, coef=coef, kd=kd, type=type)
  f
}
harrelfe/Hmisc documentation built on Oct. 3, 2019, 9:34 p.m.