I stuck in another "7" in one of the lines with a 2 and reasoned that
we could deal with the desire for non-ordered "pair counting" by
pasting min(x,y) to max(x,y);
> dput(prmtx)
structure(c(2, 1, 3, 9, 5, 7, 7, 8, 1, 7, 6, 5, 6, 2, 2, 7), .Dim =
c(4L,
4L))
> prmtx
[,1] [,2] [,3] [,4]
[1,] 2 5 1 6
[2,] 1 7 7 2
[3,] 3 7 6 2
[4,] 9 8 5 7
> pair.str <- sapply(1:nrow(prmtx), function(z)
apply(combn(prmtx[z,], 2), 2,function(x) paste(min(x[2],x[1]),
max(x[2],x[1]), sep=".")))
The logic:
sapply(1:nrow(prmtx), ... just loops over the rows of the matrix.
combn(prmtx[z,], 2) ... returns a two row matrix of combination in a
single row.
apply(combn(prmtx[z,], 2), 2 ... since combn( , 2) returns a matrix
that has two _rows_ I needed to loop over the columns.
paste(min(x[2],x[1]), max(x[2],x[1]), sep=".") ... stick the minimum
of a pair in front of the max and separates them with a period to
prevent two+ digits from being non-unique
Then using table() and logical tests in an index for the desired
multiple pairs:
> tpair <-table(pair.str)
> tpair
pair.str
1.2 1.5 1.6 1.7 2.3 2.5 2.6 2.7 3.6 3.7 5.6 5.7 5.8 5.9 6.7 7.7 7.8
7.9 8.9
2 1 1 2 1 1 2 3 1 1 1 1 1 1 1 1 1
1 1
> tpair[tpair>1]
pair.str
1.2 1.7 2.6 2.7
2 2 2 3
--
David.
On Nov 16, 2009, at 7:02 AM, David Winsemius wrote:
I'm not convinced it's right. In fact, I'm pretty sure the last step
taking only the first half of the list is wrong. I also do not know
if you have considered how you want to count situations like:
3 2 7 4 5 7 ...
7 3 8 6 1 2 9 2 ......
How many "pairs" of 2-7/7-2 would that represent?
--
David
On Nov 15, 2009, at 11:06 PM, cindy Guo wrote:
Hi, David,
The matrix has 20 columns.
Thank you very much for your help. I think it's right, but it seems
I need some time to figure it out. I am a green hand. There are so
many functions here I never used before. :)
Cindy
On Sun, Nov 15, 2009 at 5:19 PM, David Winsemius <dwinsem...@comcast.net
> wrote:
Assuming that the number of columns is 4, then consider this
approach:
> prs <-scan()
1: 2 5 1 6
5: 1 7 8 2
9: 3 7 6 2
13: 9 8 5 7
17:
Read 16 items
prmtx <- matrix(prs, 4,4, byrow=T)
#Now make copus of x.y and y.x
pair.str <- sapply(1:nrow(prmtx), function(z)
c(apply(combn(prmtx[z,], 2), 2,function(x) paste(x[1],x[2],
sep=".")) , apply(combn(prmtx[z,], 2), 2,function(x)
paste(x[2],x[1], sep="."))) )
tpair <-table(pair.str)
# This then gives you a duplicated list
> tpair[tpair>1]
pair.str
1.2 2.1 2.6 2.7 6.2 7.2 7.8 8.7
2 2 2 2 2 2 2 2
# So only take the first half of the pairs:
> head(tpair[tpair>1], sum(tpair>1)/2)
pair.str
1.2 2.1 2.6 2.7
2 2 2 2
--
David.
On Nov 15, 2009, at 8:06 PM, David Winsemius wrote:
I could of course be wrong but have you yet specified the number of
columns for this pairing exercise?
On Nov 15, 2009, at 5:26 PM, cindy Guo wrote:
Hi, All,
I have an n by m matrix with each entry between 1 and 15000. I want
to know
the frequency of each pair in 1:15000 that occur together in rows.
So for
example, if the matrix is
2 5 1 6
1 7 8 2
3 7 6 2
9 8 5 7
Pair (2,6) (un-ordered) occurs together in rows 1 and 3. I want to
return
the value 2 for this pair as well as that for all pairs. Is there a
fast way
to do this avoiding loops? Loops take too long.
and provide commented, minimal, self-contained, reproducible code.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
