[R] How to compare X1 = X2 = ... = Xn?

[Liaw, Andy]

Stupid me: fell into this trap:

> 0 == 0 == 0
[1] FALSE

Andy

> From: Sundar Dorai-Raj
> 
> Liaw, Andy wrote:
> 
> > Here's an alternative:
> > 
> > 
> >>x <- data.frame(X1 = c(1, 1, 2, 4),
> > 
> > +                  X2 = c(4, 1, 2, 5),
> > +                  X3 = c(2, 1, 2, 2))
> > 
> >>check <- paste(names(x), collapse=" == ")
> >>with(x, eval(parse(text=check)))
> > 
> > [1] FALSE  TRUE FALSE FALSE
> 
> Oops. Should be
> 
>  > [1] FALSE  TRUE  TRUE FALSE
> 
> This is TRUE for the second case by accident since the second 
> element is 1.
> 
>  > x$X4 <- (x$X1 == x$X2)
>  > as.numeric(x$X4)
> [1] 0 1 1 0
>  > x$X4 == x$X3
> [1] FALSE  TRUE FALSE FALSE
>  >
> 
> 
> 
>