Message-ID: <20120213223803.GA32301@cs.cas.cz>
Date: 2012-02-13T22:38:03Z
From: Petr Savicky
Subject: non-isomorphic sequences
In-Reply-To: <1329170691.50751.YahooMailNeo@web112505.mail.gq1.yahoo.com>
On Mon, Feb 13, 2012 at 02:04:51PM -0800, zheng wei wrote:
> Dear Petr,
> ?
> This is fantastic!
> ?
> I have one more question, when p=4, tt=4. We have 15 non-isomorphic sequences as you have generated. Among these 15, I selected?2 sequences. How do I recover all the members of the equivalent classes corresponding to these?2 sequences? For example, corresponding to the sequence of?1111, I would like to recover 1111,2222,3333,4444 from this sequence.
Dear Wei:
Try the following.
getEquivalent <- function(a, tt)
{
b <- as.matrix(rev(expand.grid(rep(list(1:tt), times=max(a)))))
ok <- apply(b, 1, function(x) length(unique(x))) == ncol(b)
b <- b[ok, , drop=FALSE]
dimnames(b) <- NULL
t(apply(b, 1, function(x) x[a]))
}
getEquivalent(c(1, 1, 1, 1), 4)
[,1] [,2] [,3] [,4]
[1,] 1 1 1 1
[2,] 2 2 2 2
[3,] 3 3 3 3
[4,] 4 4 4 4
getEquivalent(c(1, 1, 1, 2), 4)
[,1] [,2] [,3] [,4]
[1,] 1 1 1 2
[2,] 1 1 1 3
[3,] 1 1 1 4
[4,] 2 2 2 1
[5,] 2 2 2 3
[6,] 2 2 2 4
[7,] 3 3 3 1
[8,] 3 3 3 2
[9,] 3 3 3 4
[10,] 4 4 4 1
[11,] 4 4 4 2
[12,] 4 4 4 3
Hope this helps.
Petr.