获取match.call()以使用*apply&;普利尔?(re:递归引用数据帧)
以下功能的目的是更方便地进行自参考作业。(如此处所示:) 因此获取match.call()以使用*apply&;普利尔?(re:递归引用数据帧),r,plyr,apply,assign,sapply,R,Plyr,Apply,Assign,Sapply,以下功能的目的是更方便地进行自参考作业。(如此处所示:) 因此 # this myDataFrame$variable[is.na(myDataFrame$variable)] <- 0 # we can have this: NAto0(myDataFrame$variable) 也许在selfAssign中有类似于sys.parent(n)(我试过了,要么我没有弄好,要么它不起作用) 如有任何建议,将不胜感激 功能 这些函数是自我分配的包装器,是将在*apply调用
# this
myDataFrame$variable[is.na(myDataFrame$variable)] <- 0
# we can have this:
NAto0(myDataFrame$variable)
也许在selfAssign中有类似于sys.parent(n)
(我试过了,要么我没有弄好,要么它不起作用)
如有任何建议,将不胜感激
功能 这些函数是自我分配的包装器,是将在
*apply
调用中使用的函数
NAtoNULL <- function(obj, n=1) {
# replace NA's with NULL
selfAssign(match.call()[[2]], is.na(obj), NULL, n=n+1)
}
NAto0 <- function(obj, n=1) {
# replace NA's with 0
selfAssign(match.call()[[2]], is.na(obj), 0, n=n+1)
}
NAtoVal <- function(obj, val, n=1) {
selfAssign(match.call()[[2]], is.na(obj), val, n=n+1)
}
ZtoNA <- function(obj, n=1) {
# replace 0's with NA
# TODO: this may have to be modified if obj is matrix
ind <- obj == 0
selfAssign(match.call()[[2]], ind, NA, n=n+1)
}
注意,我不支持这种类型的东西,但我支持理解R是如何工作的,这样你就可以做这些东西,如果你想做的话 以下内容仅适用于
sapply
,因此它只能部分回答您的问题,但它确实列出了您可以采取的策略。正如我在前面的评论中所指出的那样,要使这一功能变得强大是非常困难的,但我可以在sapply
调用的特定上下文中回答1和2
sys.calls
获取跟踪堆栈sys.frame
和sys.parents
获得适当的评估环境get_sapply_call <- function(x) get_sapply_call_core(x) # To emulate your in-between functions
get_sapply_call_core <- function(x) {
if((c.len <- length(s.calls <- sys.calls())) < 4L) return("NULL")
if(s.calls[[c.len - 2L]][[1L]] == quote(lapply) & # Target sapply calls only
s.calls[[c.len - 3L]][[1L]] == quote(sapply) &
s.calls[[c.len - 1L]][[1L]] == quote(FUN)) {
mc.FUN <- s.calls[[c.len - 1L]]
mc.sa <- match.call(definition=sapply, s.calls[[c.len - 3L]]) # only need to match sapply b/c other calls are not user calls and as such structure is known
call.txt <- paste0(
as.character(mc.sa[[2L]]), "[[", mc.FUN[[2L]][[3L]],
"]] <- rep(NA, length(", as.character(mc.sa[[2L]]), "[[", mc.FUN[[2L]][[3L]],
"]]))"
)
call <- parse(text=call.txt)
eval(call, envir=sys.frame(sys.parents()[c.len - 3L]))
return(call.txt)
}
return("NULL")
}
df <- data.frame(a=1:10, b=letters[1:10])
sapply(df, get_sapply_call)
# a b
# "df[[1]] <- rep(NA, length(df[[1]]))" "df[[2]] <- rep(NA, length(df[[2]]))"
df
# a b
# 1 NA NA
# 2 NA NA
# 3 NA NA
# 4 NA NA
# ...
get\u sapply\u调用同样,我意识到df[is.na(df)]通常的警告:R是一种传递值语言,你试图违背自然,修改传递给函数的对象,而不必用函数的输出重新分配它们,也就是说,你想做f(x)
而不是x,您可能遇到与基本调用功能相同的困难。从文档中可以看出:“Recall”作为函数参数传递时无法正常工作,例如,传递到“apply”函数系列..@flodel,感谢您指出Recall。你可能是对的,有一个类似的原因。至于通常的警告,也谢谢你。这当然很难,但我愿意听到更多关于潜在危险和陷阱的信息。这里的特殊问题(…在不存在的情况下用于SIUTION)是,您正在将sapply发出的调用与您的函数进行匹配,该调用包括…
,但您的函数没有。有很多方法可以解决这个问题,但更大的问题是,即使您匹配调用,sapply使用的变量名也是X
,这可能不是您要设置的变量名。您必须在整个调用堆栈中寻找实际的变量名。对于非常具体的实例(例如sapply),您可能可以这样做,但这几乎不可能概括。
selfAssign <- function(self, ind, val, n=1, silent=FALSE) {
## assigns val to self[ind] in environment parent.frame(n)
## self should be a vector. Currently will not work for matricies or data frames
## GRAB THE CORRECT MATCH CALL
#--------------------------------------
# if nested function, match.call appropriately
if (class(match.call()) == "call") {
mc <- (match.call(call=sys.call(sys.parent(1)))) ## THIS LINE PROBABLY NEEDS MODIFICATION
} else {
mc <- match.call()
}
# needed in case self is complex (ie df$name)
mc2 <- paste(as.expression(mc[[2]]))
## CLEAN UP ARGUMENT VALUES
#--------------------------------------
# replace logical indecies with numeric indecies
if (is.logical(ind))
ind <- which(ind)
# if no indecies will be selected, stop here
if(identical(ind, integer(0)) || is.null(ind)) {
if(!silent) warning("No indecies selected")
return()
}
# if val is a string, we need to wrap it in quotes
if (is.character(val))
val <- paste('"', val, '"', sep="")
# val cannot directly be NULL, must be list(NULL)
if(is.null(val))
val <- "list(NULL)"
## CREATE EXPRESSIONS AND EVAL THEM
#--------------------------------------
# create expressions to evaluate
ret <- paste0("'[['(", mc2, ", ", ind, ") <- ", val)
# evaluate in parent.frame(n)
eval(parse(text=ret), envir=parent.frame(n))
}
get_sapply_call <- function(x) get_sapply_call_core(x) # To emulate your in-between functions
get_sapply_call_core <- function(x) {
if((c.len <- length(s.calls <- sys.calls())) < 4L) return("NULL")
if(s.calls[[c.len - 2L]][[1L]] == quote(lapply) & # Target sapply calls only
s.calls[[c.len - 3L]][[1L]] == quote(sapply) &
s.calls[[c.len - 1L]][[1L]] == quote(FUN)) {
mc.FUN <- s.calls[[c.len - 1L]]
mc.sa <- match.call(definition=sapply, s.calls[[c.len - 3L]]) # only need to match sapply b/c other calls are not user calls and as such structure is known
call.txt <- paste0(
as.character(mc.sa[[2L]]), "[[", mc.FUN[[2L]][[3L]],
"]] <- rep(NA, length(", as.character(mc.sa[[2L]]), "[[", mc.FUN[[2L]][[3L]],
"]]))"
)
call <- parse(text=call.txt)
eval(call, envir=sys.frame(sys.parents()[c.len - 3L]))
return(call.txt)
}
return("NULL")
}
df <- data.frame(a=1:10, b=letters[1:10])
sapply(df, get_sapply_call)
# a b
# "df[[1]] <- rep(NA, length(df[[1]]))" "df[[2]] <- rep(NA, length(df[[2]]))"
df
# a b
# 1 NA NA
# 2 NA NA
# 3 NA NA
# 4 NA NA
# ...