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)
}

Answer 1

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