How to write a is.customClass function in R?

Question

We all know functions like is.data.frame or is.double etc. Probably easy to do but hard to google: How can create your own is.? function? Is there a better way to do it then:

is.myClass <- function(x){
if(class(x) %in% "myClass") return(TRUE)
else return(FALSE)
}

This question seems related: http://stackoverflow.com/questions/5158830/identify-all-objects-of-given-class-for-further-processing — Chase, Nov 28 '12 at 16:23
I think that should go the other way around: `function(x) {"myClass" %in% class(x)}`, but as @James points out `inherits` is more idiomatic (I don't know whether it has any other advantages) — Ben Bolker, Nov 28 '12 at 16:32

score 4 · Accepted Answer · answered Nov 28 '12 at 16:24

4

Perhaps inherits is enough:

is.myClass <- function(x) {inherits(x,"myClass")}

x <- 1
is.myClass(x)
[1] FALSE
class(x) <- c(class(x),"myClass")
is.myClass(x)
[1] TRUE

answered Nov 28 '12 at 16:24

James

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You don't need `{` and `}` for single line functions – hadley Nov 28 '12 at 16:44
@hadley force of habit. Can't remember if the intepreter imposes a penalty for using them. – James Nov 28 '12 at 16:52
2

remembering whether or not there is a interpreter penalty is a waste of time; it just looks ugly to my eyes – hadley Nov 28 '12 at 16:53

How to write a is.customClass function in R?

1 Answers1