CODEWITHSUNDEEP
r
Bertie
Bertie

Reputation: 1193

How to test when condition returns numeric(0) in R

Let's imagine you would like to construct a simple test based on the condition setdiff(input, 1:9).

How can I construct an 

if isnotempty(setdiff(input, 1:9)) stop ("not valid")

statement which stops execution when input is c(3, 12) but continues when input is c(2,5,7) say? Many thanks, Bertie

Upvotes: 40

Views: 75303

Answers (6)

Tyler Rinker
Tyler Rinker

Reputation: 109874

Here's another option identical(x, numeric(0)). Here's an example (basically took everything from sgibb and replaced the key line as I'm lazy):

isEmptyNumeric <- function(x) {
    return(identical(x, numeric(0)))
}

input <- c(3, 12)

if (!isEmptyNumeric(setdiff(input, 1:9))) {
    stop ("not valid")
}

Upvotes: 26

BqKaXeu29y
BqKaXeu29y

Reputation: 103

Another option is rlang::is_bare_numeric()

Upvotes: 0

Andrii
Andrii

Reputation: 3043

I used the following functions:

# 1. Check if 'integer(0)'
is.integer0 <- function(x) {
  is.integer(x) && length(x) == 0L
}

# 2. Check if 'numeric(0)'
is.numeric0 <- function(x) {
  identical(x, numeric(0))
}

# 3. Check is 'integer0' or 'numeric0'
is.int_num_0 <- function(x) {
  is.integer0(x) || is.numeric0(x)
}

Hope it will be useful.

Upvotes: 3

i love mistaking
i love mistaking

Reputation: 103

I liked the isEmpty function. I propose the following, just in case you parse a vector, or a list:

isEmpty <- function(x) {
s<-sapply(x, function(y) length(y)==0, simplify = T)
return(s)
}

Upvotes: 0

flodel
flodel

Reputation: 89067

This does not answer the question in your subject line, but I think it is a better approach for what you are trying to achieve:

 if(!all(input %in% 1:9)) stop("not valid")

Upvotes: 0

sgibb
sgibb

Reputation: 25736

You could use ?length:

isEmpty <- function(x) {
    return(length(x)==0)
}

input <- c(3, 12);

if (!isEmpty(setdiff(input, 1:9))) {
    stop ("not valid")
}

Upvotes: 57

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