[R] Odp: Help How to use a loop to do pair comparison

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 24.02.2009 06:23:23:

> Hi R users,
> 
> I have a question. How can I use for loop to do pair comparisons. For
> example,
> 
> > x<-c(1,2,3)
> 
> > result<-matrix(data=NA, nrow=choose(3,2), ncol=1)
> 
> > for(i in 1: length(x))
> 
> +    { result[i,]<-ifelse(x[i] > x[i+1], yes="Big", no="Small")
> 
> +     result}
> 
> > result
> 
>      [,1] 
> 
> [1,] "Small"
> 
> [2,] "Small"
> 
> [3,] NA 

Well. It is a little cryptic what you want. 

Suppose you have 100 x values. What is x value number 101? 

If you want to check if subsequent value is bigger or smaller then 
previous one use

diff(x) and test diff(x)>0.

Regards
Petr


> 
> 
> 
> I want to compare (1 vs. 2), (1 vs. 3), (2 vs.3) 
> 
> I know I miss something but I just can not get it work. Could anyone 
give me
> a hint?
> 
> 
> 
> Appreciate,
> 
> Chunhao 
> 
> 
>    [[alternative HTML version deleted]]
> 
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