Return specific element of vector in list

I have a list of vectors of strings. And I have a vector with indexes. I would like to return the indexed string in each list element.

> list = list(c("monday","tuesday","wednesday"),c("thursday","friday","saturday"),"sunday")
> list
[[1]]
[1] "monday"    "tuesday"   "wednesday"

[[2]]
[1] "thursday" "friday"   "saturday"

[[3]]
[1] "sunday"

> vector = c(2,3,1)
> vector
[1] 2 3 1

> goal=c("tuesday","saturday","sunday")
> goal
[1] "tuesday"  "saturday" "sunday" 

I can get the first element like this:

lapply(list,"[[",1)

but I cannot index the vector.

I also tried making the vector a list and append it:

mapply(append,list,as.list(vector),simplify=F)

And I get a list where the last string in each element is a string of the index. But I cannot return the index and use it as a numeric to find the respective string.

I am unsure why you are trying to use append at all here. Your first approach was essentially correct: Use [[. But you need to map over the indices as well as the list, using mapply:

mapply(`[[`, list, vector)

There is also the option of using purrr from the tidyverse collection of packages. The main advantage of using map_* instead of mapply is the consistent interface between map variants.

map2_chr(list, vector, `[[`)

Another option:

unlist(Map(function(x, i) x[i], list, vector))
[1] "tuesday"  "saturday" "sunday"