round to specific intervals

Thanks for all the response,

I manage to write a small function to complete what I want based on the 
wonderful helps.

iround <- function(x, interval){
     ## Round numbers to desired interval
     ##
     ## Args:
     ##   x:        Numeric vector to be rounded
     ##   interval: The interval the values should be rounded towards.
     ## Retunrs:
     ##   a numeric vector with x rounded to the desired interval.
     ##
     interval[ifelse(x < min(interval), 1, findInterval(x, interval))]
}

iround(0:100, c(1, 5, 10, 20, 50))

Cheers, and thanks for all the help again.

On 01/12/2011 10:55 AM, Michael Kao wrote:

Dear R users/helpers,

I am wondering is there an existing function in which you can round
numbers to a set of values. I know you can use 5 * round(x/5) for
rounding to the nearest 5 or so, but what if the interval size is not
constant.

For example:
## Not run
test<- rnorm(100)
round(test, c(1, 5, 10, 20, 50))

so that the test is rounded to the closest value in the vector.

I think you could put together such a thing using cut().

Duncan Murdoch