if command to test for integer(0)

Question

I'm using a command to return the points at which participants reach 8 contiguous responses in a row. The command is:

 test <- which( rle(goo)$values==1 & rle(goo)$lengths >= 8)

where:

 goo <- c(1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0)

if the participant never achieves 8 contiguous responses i'd like to set the variable "test" to equal -1. As it stands, the command returns integer(0) when 8 contiguous responses in a row are not found. I've tried writing an if command but can't seem to get it right.

Thanks in advance,

Will

Answer 1

If test is integer(0) then its length is 0. You can also coerce it to logical with !

length(test)
0
!(length(test)
TRUE    # and would be FALSE for any vector with normal length
> !(length( c(1,2,3) ))
[1] FALSE

So:

> if ( !length(test) ) {test<- -1} 

> test
[1] -1