CODEWITHSUNDEEP
r
Tyler Rinker
Tyler Rinker

Reputation: 109874

Stop lapply from printing to console

When I use lapply and print to the console it prints unwanted [[i]]NULL though I want the intended message to print to the console. I've tried suppressWarnings and suppressMessages but these do not remove the unwanted offender. I searched lapply and don't see an argument to silence it. This is more aesthetic as it doesn't interfere with the function. I'm not opposed to allternative printing to the console so long as the user can turn it off if they wish.

Here's an example function, the output and what I'd like to get:

Sample function:

FUN <- function(x) {
    FUN2 <- function(z) message(z)
    lapply(1:3, function(i) FUN2(paste(x, i)))
}

FUN("hello")

Output:

hello 1
hello 2
hello 3
[[1]]
NULL

[[2]]
NULL

[[3]]
NULL

Desired Output:

hello 1
hello 2
hello 3

Upvotes: 51

Views: 15429

Answers (3)

andschar
andschar

Reputation: 3973

You could use a plain ol' for loop instead of lapply():

FUN <- function(x) {
  for (i in 1:3) {
    message(paste0(x, i))
  }
}
FUN("hello")

Upvotes: 1

hadley
hadley

Reputation: 103898

Use l_ply from plyr:

library(plyr)
FUN <- function(x) {
    FUN2 <- function(z) message(z)
    l_ply(1:3, function(i) FUN2(paste(x, i)))
}
FUN("hello")

Upvotes: 9

James
James

Reputation: 66834

Use invisible, eg:

invisible(FUN("hello"))
hello 1
hello 2
hello 3

You can wrap it around the lapply call in the function too to make it tidier.

Upvotes: 64

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