如何将两个向量的元素合并到列表中并根据原始向量保留名称？

Question

I'm trying to find an elegant way to link function parameters and an httr 's call query list. Assume we have two character vectors, indicating animals and colors

animals = "dog"
colors = "red"

If I use the query parameter

list(animal=animals,color=colors)

it will produce the expected result. On the other hand, if I want multiple parameters for one of the components

animals = c("dog","cat")

the same list would create

$animal
[1] "dog" "cat"

$color
[1] "red"

when httr requires a list like

$animal
[1] "dog"

$animal
[1] "cat"

$color
[1] "red"

How can I elegantly create the appropriate list, where instead of having a character vector as an element, multiple elements with the same name would be created?

Answer 1

Try:

foo <- list(animals = c("dog","cat"), color = "red")
foo <- as.list(unlist(foo))
foo <- setNames(foo, gsub("[[:digit:]]", "", names(foo)))

The list becomes less useful since selecting by name doesn't work, but should be the format you want. Renaming isn't great if your list has numbers, but that might be something you have to work out separately.

Update:

I don't like renaming with regular expressions. You can also try something like this to remove that last line:

as.list(setNames(unlist(foo), rep(names(foo), sapply(foo, length))))

It's a little more exact that using setNames and gsub .

Answer 2

c(animals=as.list(animals),colors=colors)
$animals1
[1] "dog"

$animals2
[1] "cat"

$colors
[1] "red"