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`numPerms` <- function(object, control = how()) {
## constant holding types where something is permuted
TYPES <- c("free","grid","series","none")
## expand object if a numeric or integer vector of length 1
if((is.numeric(object) || is.integer(object)) &&
(length(object) == 1))
object <- seq_len(object)
## number of observations in data
n <- nobs(object)
## get the permutation levels from control
WI <- getWithin(control)
PL <- getPlots(control)
BL <- getBlocks(control)
## any strata to permute within / blocking?
BLOCKS <- getStrata(control, which = "blocks")
PSTRATA <- getStrata(control, which = "plots")
typeP <- getType(control, which = "plots")
typeW <- getType(control, which = "within")
## mirroring?
mirrorP <- getMirror(control, which = "plots")
mirrorW <- getMirror(control, which = "within")
## constant - i.e. same perm within each plot?
constantW <- getConstant(control)
## grid dimensions
colW <- getCol(control, which = "within")
colP <- getRow(control, which = "plots")
## Some checks; i) Plot strata must be of same size when permuting strata
## or having the same constant permutation within strata
## ii) In grid designs, grids must be of the same size for all
## strata
##
## FIXME - this probably should be in check()!
if(!is.null(PSTRATA)) {
tab <- table(PSTRATA)
same.n <- length(unique(tab))
if((typeP != "none" || isTRUE(constantW)) && same.n > 1) {
stop("All levels of strata must have same number of samples for chosen scheme")
}
if(typeP == "grid" && same.n > 1) {
stop("Unbalanced grid designs are not supported")
}
}
## the various designs allowed imply multipliers to number of samples
## for the restricted permutations
mult.p <- mult.wi <- 1
## within types
if(typeW %in% c("series","grid")) {
mult.wi <- 2
if(isTRUE(all.equal(typeW, "grid")) && !is.null(colW) && colW > 2) {
mult.wi <- 4
} else {
if(isTRUE(all.equal(n, 2)))
mult.wi <- 1
}
}
## plot-level types
if(typeP %in% c("series","grid")) {
mult.p <- 2
if(isTRUE(all.equal(typeP, "grid")) && !is.null(colP) && colP > 2) {
mult.p <- 4
} else {
if(isTRUE(all.equal(n, 2)))
mult.p <- 1
}
}
## within
## another check - shouldn't this be moved? FIXME
if(!typeW %in% TYPES) {
stop("Ambiguous permutation type in 'control$within$type'")
}
## calculate the number of possible permutations
## Compute number of permutations for each block
if(is.null(BLOCKS))
BLOCKS <- factor(rep(1, n))
## split an index vector
indv <- seq_len(n)
spl <- split(indv, BLOCKS)
## loop over the components of spl & apply doNumPerms
np <- sapply(spl, doNumPerms, mult.p, mult.wi, typeP, typeW, PSTRATA,
mirrorP, mirrorW, constantW)
## multiply up n perms per block
prod(np)
}
`doNumPerms` <- function(obs, mult.p, mult.wi, typeP, typeW, PSTRATA,
mirrorP, mirrorW, constantW) {
n <- nobs(obs) ## obs is index vector for object, split by blocks
if(!is.null(PSTRATA)) {
## take only the PSTRATA needed for this block, drop unused levels
PSTRATA <- droplevels(PSTRATA[obs])
## need only those strata for the current block. As obs is the index
## vector, split by block, this now gives nobs per plot strata
tab <- table(PSTRATA)
same.n <- length(unitab <- unique(tab))
}
## plots
num.p <- if(isTRUE(all.equal(typeP, "free"))) {
exp(lfactorial(length(levels(PSTRATA))))
} else if(typeP %in% c("series", "grid")) {
if(isTRUE(mirrorP)) {
mult.p * n
} else {
n
}
} else {
1
}
num.wi <- if(isTRUE(all.equal(typeW, "none"))) {
## no within permutations. note we multiply num.p by this
## values so it is 1 not 0!!
1
} else if(isTRUE(all.equal(typeW, "free"))) {
if(!is.null(PSTRATA)) {
if(constantW) {
factorial(tab[1])
} else {
prod(factorial(tab))
}
} else {
exp(lfactorial(n))
}
} else {
if(!is.null(PSTRATA)) {
if(same.n > 1) {
multi <- rep(2, length = length(tab))
multi[which(tab == 2)] <- 1
if(mirrorW) {
prod(multi * tab)
} else {
prod(tab)
}
} else {
if(mirrorW) {
if(constantW)
mult.wi * unitab
else
prod(mult.wi * tab)
} else {
if(constantW)
unitab ## FIXME: unitab[1]?? (unique(tab)[1])
else
prod(tab)
}
}
} else {
if(mirrorW)
mult.wi * n
else
n
}
}
## return
num.p * num.wi
}
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