R:从嵌套列表中按名称获取元素 [英] R: get element by name from a nested list
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问题描述
我有一个像这样的嵌套列表:
I have a nested list like so:
smth <- list()
smth$a <- list(a1=1, a2=2, a3=3)
smth$b <- list(b1=4, b2=5, b3=6)
smth$c <- "C"
列表中每个元素的名称都是唯一的.
The names of every element in the list are unique.
我只想通过名称从这样的列表中获取一个元素,而不知道它的位置.
I would like to get an element from such a list merely by name without knowing where it is located.
示例:
getByName(smth, "c")
="C"
getByName(smth, "b2")
= 5
我也不希望使用unlist
,因为实际列表中包含很多繁重的元素.
Also I don't really want to use unlist
since the real list has a lot of heavy elements in it.
推荐答案
到目前为止,最佳的解决方案是:
The best solution so far is the following:
rmatch <- function(x, name) {
pos <- match(name, names(x))
if (!is.na(pos)) return(x[[pos]])
for (el in x) {
if (class(el) == "list") {
out <- Recall(el, name)
if (!is.null(out)) return(out)
}
}
}
rmatch(smth, "a1")
[1] 1
rmatch(smth, "b3")
[1] 6
Full credit goes to @akrun for finding it and mbedward for posting it here
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