如何将数字向量列表转换为具有公共前缀的文本向量列表？

Question

So I have a list of numeric vectors, and I need to convert it to a similar list of character "strings", each with a common prefix.

So I start out simple:

> aNumVect = c(1,2,3,4,5,6)
> aNumVect
[1] 1 2 3 4 5 6
> paste(sep="", "X", aNumVect)
[1] "X1" "X2" "X3" "X4" "X5" "X6"
> 

Ah, perfect! Exactly what I need. Except I need to do it to a list of numeric vectors:

> aListOfNumVects = list(c(1,2,3,4,5,6), c(7,8,9,10,11,12))
> aListOfNumVects
[[1]]
[1] 1 2 3 4 5 6

[[2]]
[1]  7  8  9 10 11 12

> paste(sep="", "X", aListOfNumVects)
[1] "Xc(1, 2, 3, 4, 5, 6)"    "Xc(7, 8, 9, 10, 11, 12)"

OK, no, that is NOT what I need. I need the result to look like this:

[[1]]
[1] "X1" "X2" "X3" "X4" "X5" "X6"

[[2]]
[1]  "X7"  "X8"  "X9" "X10" "X11" "X12"

How can I get that, short of manually looping & converting the list one vector at a time? Which, by the way, isn't too difficult....

> XprefixedListOfNumVects = list()
> for (i in 1:length(aListOfNumVects))
+    XprefixedListOfNumVects[[i]] = paste(sep="", "X", aListOfNumVects[[i]])
> XprefixedListOfNumVects
[[1]]
[1] "X1" "X2" "X3" "X4" "X5" "X6"

[[2]]
[1] "X7"  "X8"  "X9"  "X10" "X11" "X12"

....but I know there's gotta be a smarter way.

Answer 1

You can use lapply() , which applies a function to each element of a list:

lapply(aListOfNumVects, function(y) paste0("X", y))
[[1]]
[1] "X1" "X2" "X3" "X4" "X5" "X6"

[[2]]
[1] "X7"  "X8"  "X9"  "X10" "X11" "X12"