[R] Expand duplicated observations

[M. P. Papadatos]

Dear all,

I am trying to  expand duplicated observations. I need to replace  
each observation in the dataset with n copies of the observation,  
where n is equal to the required expression rounded to the nearest  
integer. If the expression is less than 1 or equal to missing, it is  
interpreted as if it were 1, and the observation is retained but not  
duplicated.

Example

From
c(1,2,3)

To
c(1,2,2,3,3,3)

Thank you in advance.

Best wishes,
Martin