[R] Summary for mode of a data set

[Spencer Graves]

Your "mode1" function will identify multiple modes only if they have the 
same number of observations.  Consider the following:

 > x2 <- c(2, 1,1, 3,3,3)
 > mode1(x2)
[1] 3

Here, "mode1" did not identify the local mode at 1, because it had fewer 
observations than 3.  If you want the modes at both 1 and 3, then 
consider the following:

modes <- function(x){
	xt <- table(x)
	nt <- length(xt)
	sel <- c(xt[-nt]>=xt[-1], T)&c(T, xt[-1]>=xt[-nt])
	as.numeric(names(xt[sel]))
}
 > modes(x2)
[1] 1 3

hth.  spencer graves

Erin Hodgess wrote:
> Dear R People:
> 
> thank you for the many helpful sets of code that I received!!!
> 
> I combined several of the concepts for the following function:
> 
> 
>>mode1
> 
> 
> function(x) {
> 
>         y <- rle(sort(x))
> 
>         z <- y$values[y$lengths==max(y$lengths)]
> 
>         return(z)
> 
> }
> 
> 
>>xm
> 
> 
>  [1] 22 15 10 30 25 26  2 17 28  2 24  6 26 24  5 22 20 14
> 
> 
>>mode1(xm)
> 
> 
> [1]  2 22 24 26
> 
> 
> 
> This will pick up multiple modes.
> 
> Again thanks to all who helped!
> 
> Sincerely,
> Erin 
> mailto: hodgess at uhddx.01.dt.uh.edu
> 
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