[英]How to merge two lists in parallel in R?
我在問如何並行地合並兩個列表,而不是按以下代碼順序附加。
例如,
A <- list(c(1,2,3), c(3,4,5), c(6,7,8))
B <- list(c("a", "b", "c"), c("d", "e", "f"), c("g", "h", "i"))
結果,
[[1]]
[[1]][[1]]
[1] 1 2 3
[[1]][[2]]
[1] "a" "b" "c"
[[2]]
[[2]][[1]]
[1] 3 4 5
[[2]][[2]]
[1] "d" "e" "f"
[[3]]
[[3]][[1]]
[1] 6 7 8
[[3]][[2]]
[1] "g" "h" "i"
簡單地使用Map
:
Map(list,A,B)
更長的方法(尚未遞歸,直到第二級合並):
A <- list(c(1,2,3), c(3,4,5), c(6,7,8))
B <- list(c("a", "b", "c"), c("d", "e", "f"), c("g", "h", "i"))
mergepar <- function(x = A, y = B) { # merge two lists in parallel
ln <- max(length(x), length(y)) # max length
newlist <- as.list(rep(NA, ln)) # empty list of max length
for (i in 1:ln) { # for1, across length
# two level subsetting (first with [ and then [[, so no subscript out of bound error) and lapply
newlist[[i]] <- lapply(list(A, B), function(x) "[["("["(x, i), 1))
}
return(newlist)
}
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