在R
我想转换(强制?)从stats::spectrum
(类'spec')返回的对象到新的S4类中。 S3类'spec'本质上是一个混合格式的各种信息列表(我已经评论了屏幕输出):
psd3 <- spectrum(rnorm(1e3), plot=FALSE)
summary(psd3)
# Length Class Mode
# freq 500 -none- numeric
# spec 500 -none- numeric
# coh 0 -none- NULL
# phase 0 -none- NULL
# kernel 0 -none- NULL
# df 1 -none- numeric
# bandwidth 1 -none- numeric
# n.used 1 -none- numeric
# orig.n 1 -none- numeric
# series 1 -none- character
# snames 0 -none- NULL
# method 1 -none- character
# taper 1 -none- numeric
# pad 1 -none- numeric
# detrend 1 -none- logical
# demean 1 -none- logical
class(unclass(psd3))
# [1] "list"
is.object(psd3) & !isS4(psd3)
# [1] TRUE
现在假设我们为名为'specS4'的类定义一个新的S4生成器,其中插槽名称是'spec'对象中的名称
specS4 <- setClass("specS4",
representation = representation(freq="numeric", spec="numeric", coh="numeric", phase="numeric", kernel="numeric", df="numeric", bandwidth="numeric", n.used="numeric", orig.n="numeric", series="character", snames="character", method="character", taper="numeric", pad="numeric", detrend="logical", demean="logical"),
prototype = prototype(coh=numeric(0), phase=numeric(0), kernel=numeric(0), df=Inf, snames="", detrend=FALSE, demean=FALSE)
)
并从中生成一个新对象:
psd4 <- specS4()
validObject(psd4)
# [1] TRUE
将psd3
的每个组件分配到psd4
中相应的广告位的最佳方法是什么? 一个复杂因素是spectrum
可能会为少数(已知)字段返回NULL
;分配这些值会在checkSlotAssignment
中引发错误(对于给定的表示)。
我有一个痛苦的解决方案是:
nonull.spec <- function(psd){
stopifnot(inherits(psd, 'spec', FALSE))
# as.numeric(NULL) --> numeric(0)
# spec.pgram/.ar both may return NULL for these:
psd$coh <- as.numeric(psd$coh)
psd$phase <- as.numeric(psd$phase)
psd$kernel <- as.numeric(psd$kernel)
psd$snames <- as.character(psd$snames)
return(psd)
}
as.specS4 <- function(psd) UseMethod("as.specS4")
as.specS4.spec <- function(psd){
stopifnot(inherits(psd, 'spec', FALSE))
## deal with possible NULLs
psd <- nonull.spec(psd)
## generate specS4 class
S4spec <- specS4()
## (re)assign from 'spec' list
S4spec@freq <- psd$freq
S4spec@spec <- psd$spec
S4spec@coh <- psd$coh
S4spec@phase <- psd$phase
S4spec@kernel <- psd$kernel
S4spec@snames <- psd$snames
# [more to assign, obviously]
#
# [run a validity check...]
#
return(S4spec)
}
哪个有效,即使as.specS4.spec
故意不完整。
psd4c <- as.specS4(psd3)
validObject(psd4c)
# [1] TRUE
有没有更好的方法来实现as.specS4.spec
的功能?这个解决方案似乎不稳定。
答案 0 :(得分:1)
我刚刚意识到这实际上是多么简单。 卫生署!
将'specS4'对象中的slotNames
与'spec'对象中的names
匹配,然后使用slot
进行匹配(假设问题中的代码已经运行):
as.specS4.spec <- function(psd){
stopifnot(inherits(psd, 'spec', FALSE))
psd <- nonull.spec(psd)
S4spec <- specS4()
spec_slots <- slotNames(S4spec)
spec_slots <- spec_slots[match(names(psd), spec_slots)]
for (what in spec_slots){
slot(S4spec, what) <- as.vector(unlist(psd[what]))
}
return(S4spec)
}
psd4c2 <- as.specS4(psd3)
validObject(psd4c2)
# [1] TRUE
> all.equal(psd4c@freq, psd4c2@freq, psd3$freq)
# [1] TRUE