How to assign from a function with multiple outputs? [duplicate]

Answer 1

The return() object needs to be one thing ... a list or a vector. If you want to "push" something else into the global (or other environment), you can use <<-, although that is considered poor practice.

Answer 2

I believe you are limited to using lists, but you can combine them like:

> list(list(a=1, b=2), list(c=3, d=4))
[[1]]
[[1]]$a
[1] 1

[[1]]$b
[1] 2


[[2]]
[[2]]$c
[1] 3

[[2]]$d
[1] 4

Answer 3

I found list2env ideal for what you're describing; the trickiest bit, for me, was working out what to give for the env parameter:

f=function(){
    list(a=1,b="my string")
}

ret=f()
list2env(ret,env=environment())
#a=ret$a;b=ret$b    #Same as previous line

print(a);print(b)   #1  and "my string"

Answer 4

You can only return one object in a function. But you have some other options. You could assign intermediate objects to the global environment (you need to be careful not to overwrite anything) or you could pass an environment to your function and assign objects to it.

Here's an example of the latter suggestion:

fun <- function(x, env) {
  env$x2 <- x^2
  x^3
}
set.seed(21)
x <- rnorm(10)
myEnv <- new.env()
fun(x, myEnv)
#  [1]  4.987021e-01  1.424421e-01  5.324742e+00 -2.054855e+00  1.061014e+01
#  [6]  8.125632e-02 -3.871369e+00 -8.171530e-01  2.559674e-04 -1.370917e-08
myEnv$x2
#  [1] 6.288699e-01 2.727464e-01 3.049292e+00 1.616296e+00 4.828521e+00
#  [6] 1.876023e-01 2.465527e+00 8.740486e-01 4.031405e-03 5.728058e-06