Round-up and round-down R

Question

It might seem silly but I have not been successful in trying to round my data as I wanted. This is an example of my array:

a<-c(-0.5:30,by=5)

What I want is: for min(a) to round-down to the next number to multiples of 10 but the max(a) to round-up.

This case:

min(a)=-0.5 and I want it round down to -10

max(a)=29.5 and I want to round up (to 30 or 40).

I have spent time to think and search for it but have not found anything. Any help would be highly appreciated.

Regards, Phuong

Answer 1

a<- seq(from = -0.5, to = 30, by = 5) 

For rounding up max:

roundUp <- function(x,to=10)
{
  to*(x%/%to + as.logical(x%%to))
}
roundUp(max(a))

For rounding down min:

roundDw <- function(x,to=-10)
{
  to*(x%/%to + as.logical(x%%to))
}
roundDw(min(a))