Putting print in replicate in R

Question

Please look at the following code in R

i=1
a1=function(x){
  print(i)
  i=i+1
  return(x^2)}
a2=replicate(5,a1(2))

I wish to have an output as 1 2 3 4 5

Can anyone help me with this? However I don't want to write for-loops. I wish to keep the replicate function as it is. Thanks for suggestions/help.

You can not change the value `i` inside a function. What are you trying to do? Just print a sequence of numbers? — Psidom, Jul 05 '16 at 21:22
Yes I wish to have a count of that. Please understand that it's a MWE — Sayan, Jul 05 '16 at 21:34
The thing is that there are tons of ways to do that but probably not with `replicate`. `for` loop, `apply` family or `recursive` functions can all accomplish the task, but it may not be what you wanted at the end. — Psidom, Jul 05 '16 at 21:36
to me that feels like an abuse of `replicate()` (which suggests reproducibility, consistent results, etc.). Why not use a function like `Reduce()` or `Recall()` that is better suited to this task? — baptiste, Jul 05 '16 at 21:37
The statement of Psidom is wrong. See the answer below. If you want to learn about scoping in R I recommend this http://stackoverflow.com/questions/2628621/how-do-you-use-scoping-assignment-in-r. — Alex, Jul 05 '16 at 21:38

score 1 · Answer 1 · answered Jul 05 '16 at 21:34

You can do this via global variable assignment:

i=1
a1=function(x){
  print(i)
  i<<-i+1
  return(x^2)}
a2=replicate(5,a1(2))
# [1] 1
# [1] 2
# [1] 3
# [1] 4
# [1] 5

This is not really how you should to it.

Depending on what you are really trying to do, this can work:

res <- sapply(1:5, print)

1 Answers1