[R] I don't understand the 'order' function

[Rui Barradas]

Hello,

Inline.

Em 16-04-2013 18:51, Julio Sergio escreveu:
> I thought I've understood the 'order' function, using simple examples like:
>
>     order(c(5,4,-2))
>     [1] 3 2 1
>
> However, I arrived to the following example:
>
>     order(c(2465, 2255, 2085, 1545, 1335, 1210, 920, 210, 210, 505, 1045))
>     [1]  8  9 10  7 11  6  5  4  3  2  1
>
> and I was completely perplexed!
> Shouldn't the output vector be  11 10 9 8 7 6 4 1 2 3 5 ?

No, why should it?
Try assigning the output of order and see what happens to the vector.


x <- c(2465, 2255, 2085, 1545, 1335, 1210, 920, 210, 210, 505, 1045)
(o <- order(x) )
x[o]  # Allright


Hope this helps,

Rui Barradas

> Do I have a damaged version of R?
>
> I became still more astonished when I used the sort function and got the
> right answer:
>
>     sort(c(2465, 2255, 2085, 1545, 1335, 1210,  920,  210,  210,  505, 1045))
>     [1]  210  210  505  920 1045 1210 1335 1545 2085 2255 2465
> since 'sort' documentation claims to be using 'order' to establish the right
> order.
>
> Please help me to understand all this!
>
>    Thanks,
>
>    -Sergio.
>
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