A few days ago, someone asked how to truncate arbitrary numerics to 1
digit towards 0. e.g. -189 should become -100 and 254 should become
200; and all values in magniude < 1 should become 0.
I proposed a somewhat clumsy solution using floor() and ceiling(), but
in fooling with it a bit more, I realized that a better way to do it
is to use R's trunc() function. It is simpler and works for all cases
AFAICS. Here's a litte function to do it -- maybe someone else might
find it amusing/instructive:
poof <- function(x){
## truncating to 0
## x is a numeric vector
k <- 10^trunc(log10(abs(x)))
ifelse(k, trunc(x/k)*k, k)
}
## test it
> x <- c(0,-.036578, .4876, -189, 254)
> poof(x)
[1] 0 0 0 -100 200
Cheers,
Bert
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