Question

Possible Duplicate:
R round to nearest .5 or .1
How do I round to 1, 1.5, 2 etc instead of 1, 2 or 1.1, 1.2, 1.3 in R?

if I want to round a number with some digits after comma

a <- 2.1357

I can use

round(a, 1)

to obtain 2.1 as result.

Now let I have an array of numbers like

b <- rnorm(n = 10, mean = .5, sd = .1)
> b
[1] 0.5554950 0.4527671 0.5217543 0.6137458 0.6023219 0.7045009 0.5140363 0.5312920
[9] 0.5841152 0.4492901

If I want to round those numbers in order to make them multiples of 0.1, it’s enough to input

round(b, 1)

Now my question: what if I would like to round them in order to make the multiples of… 0.2? Or 0.3? Or 0.25… an so on?

Thanks,

Answer 1

a <- runif(20)  # Data
mult <- .125    # Multiple
mult*round(a/mult)

gets you

 [1] 0.250 0.750 0.125 0.625 0.000 0.500 0.125 0.500 0.125 0.875 1.000 0.750
[13] 0.500 0.500 0.125 0.500 0.250 0.250 0.250 0.875