[R] How to compare X1 = X2 = ... = Xn?
Sundar Dorai-Raj
sundar.dorai-raj at PDF.COM
Mon Jul 19 20:30:49 CEST 2004
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
>
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