[R] generate ordered categorical variable in R

[Marc Schwartz]

> On Sep 16, 2015, at 1:06 PM, Bert Gunter <bgunter.4567 at gmail.com> wrote:
> 
> Yikes! The uniform distribution is a **continuous** distribution over
> an interval. You seem to want to sample over a discrete distribution.
> See ?sample for that, as in:
> 
> sample(1:4,100,rep=TRUE)
> 
> ## or for this special case and faster
> 
> sample.int(4,size=100,rep=TRUE)


Bert,

I am not sure that it is really faster, since internally, sample() calls sample.int():

> sample
function (x, size, replace = FALSE, prob = NULL) 
{
    if (length(x) == 1L && is.numeric(x) && x >= 1) {
        if (missing(size)) 
            size <- x
        sample.int(x, size, replace, prob)
    }
    else {
        if (missing(size)) 
            size <- length(x)
        x[sample.int(length(x), size, replace, prob)]
    }
}


set.seed(1)

> system.time(x1 <- sample(1e10, 1e8, replace = TRUE))
   user  system elapsed 
  2.755   0.170   2.925 


set.seed(1)
> system.time(x2 <- sample.int(1e10, 1e8, replace = TRUE))
   user  system elapsed 
  2.767   0.183   2.951 


> all(x1 == x2)
[1] TRUE


Regards,

Marc


> 
> Cheers,
> Bert
> 
> Bert Gunter
> 
> "Data is not information. Information is not knowledge. And knowledge
> is certainly not wisdom."
>   -- Clifford Stoll
> 
> 
> On Wed, Sep 16, 2015 at 10:11 AM, thanoon younis
> <thanoon.younis80 at gmail.com> wrote:
>> Dear R- users
>> 
>> I want to generate ordered categorical variable vector with 200x1 dimension
>> and from 1 to 4 categories and i tried with this code
>> 
>> Q1=runif(200,1,4) the results are not just 1 ,2 3,4, but the results with
>> decimals like 1.244, 2.342,4,321 and so on ... My question how can i
>> generate a vector and also a matrix with orered categorical variables and
>> without decimals just 1,2,3 ,4 ,1,2,3,4, ....
>> 
>> Many thanks in advance