R help - Apr 2010 - Obvious reason for not looping twice?

Is there an obvious reason why this won't loop to i=2 and beyond?
There are many combinations of *st* & *vc* that don't exist in svc. For
example, when s=1 there's only an entry at v=1.  That's fine, the entry
can
stay 0.

lookup.svc <- array(0,dim=c(length(unique(svc$st)),length(unique(svc$vc))),
dimnames=list(unique(svc$st), unique(svc$vc)))

for (i in 1:length(unique(svc$st))) {
  for (j in 1:length(unique(svc$vc))){
     lookup.svc[i,j] <- svc[svc$st == unique(svc$st)[i] & svc$vc
=unique(svc$vc)[j], 4]
}}


Thanks,
Robin

~~~~~~~~~~~~~~~~~~~
-Robin Jeffries
Dr.P.H. Candidate
UCLA School of Public Health
rjeffries@ucla.edu
530-624-0428

	[[alternative HTML version deleted]]

Tena koe Robin

Do you get an error or warning?

It may have something to do with how == treats NA:

x <- 1:4
x[x == 1]
[1] 1
x <- c(1:4, NA)
x[x == 1]
[1]  1 NA
x[x %in% 1]
[1] 1

If so, using %in% is one way to avoid the problem.  However, I would
have thought you'd get an error message if this were the case.

HTH .....

Peter Alspach
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Robin Jeffries
> Sent: Monday, 26 April 2010 10:26 a.m.
> To: r-help at r-project.org
> Subject: [R] Obvious reason for not looping twice?
> 
> Is there an obvious reason why this won't loop to i=2 and beyond?
> There are many combinations of *st* & *vc* that don't exist in svc.
For
> example, when s=1 there's only an entry at v=1.  That's fine, the
entry
> can
> stay 0.
> 
> lookup.svc <-
> array(0,dim=c(length(unique(svc$st)),length(unique(svc$vc))),
> dimnames=list(unique(svc$st), unique(svc$vc)))
> 
> for (i in 1:length(unique(svc$st))) {
>   for (j in 1:length(unique(svc$vc))){
>      lookup.svc[i,j] <- svc[svc$st == unique(svc$st)[i] & svc$vc
=> unique(svc$vc)[j], 4]
> }}
> 
> 
> Thanks,
> Robin
> 
> ~~~~~~~~~~~~~~~~~~~
> -Robin Jeffries
> Dr.P.H. Candidate
> UCLA School of Public Health
> rjeffries at ucla.edu
> 530-624-0428
> 
> 	[[alternative HTML version deleted]]
> 
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