From wsimpson@uwinnipeg.ca  Thu Jul  9 01:55:53 1998
From: wsimpson@uwinnipeg.ca (Bill Simpson)
Date: Wed, 8 Jul 1998 19:55:53 -0500 (CDT)
Subject: numeric(0) -> NA
Message-ID: <Pine.OSF.3.95.980708194226.19813A-100000@io.uwinnipeg.ca>

I noticed this in current intermediate patch version:
> runif(0,0,4095)
numeric(0)
> round(runif(0,0,4095))
[1] NA

I don't like it, but maybe it is the way it is supposed to be. I would
prefer for it to stay numeric(0).

I notice also
> ceiling(runif(0,0,4095))
numeric(0)
> floor(runif(0,0,4095))
numeric(0)
which leads me to thing round() is not working right.


I have some code like this:
do.sim<-function(nnoise, nsignal, jump)
{
ntotal<-nsignal+nnoise
x<-numeric(ntotal)
y<-numeric(ntotal)

#generate noise dots
nx1<-round(runif(nnoise,0,4095))
nx2<-round(runif(nnoise,0,4095))
ny1<-round(runif(nnoise,0,4095))
ny2<-round(runif(nnoise,0,4095))

#generate signal dots
sx1<-round(runif(nsignal,0,4095))
...

and I need to do do.sim(0,1000,10). But that gives me NAs which are a
problem later. (in particular, I can't do
if(rr<rbest)
if rr is computed from an NA.)

BTW I think it is a ghastly waste of resources to do
round(runif(nnoise,0,4095))
but I couldn't think of a better way to get ints between 0 and 4095.
(It's a waste because the random number generator makes unsigned long ints
to begin with, then they are divided by 2^32 to get a double between 0
and 1, and now I am undoing that!)

I guess there is sample(,replace=true), which seems even worse for
wasted resources. Maybe not.

Thanks for any help.

Bill Simpson

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numeric(0) -> NA
Bill Simpson