From: hadley wickham <h.wickham_at_gmail.com>

Date: Tue 18 Oct 2005 - 08:31:39 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Tue Oct 18 08:36:32 2005

Date: Tue 18 Oct 2005 - 08:31:39 EST

Or more simply:

averank<-sort(sample(1:100,10,replace=TRUE)) outer(averank, averank, "-")

Hadley

On 10/17/05, Robert Baer <rbaer@atsu.edu> wrote:

> I think I misunderstood your follow-up question. Try this:

*>
**> > averank<-sort(sample(1:100,10,replace=TRUE))
**> > x=matrix(nrow=length(averank),ncol=length(averank))
**> > for (i in 1:length(averank)){
**> + for (j in 1:length(averank)){
**> + x[i,j] <- averank[i] - averank[j]
**> + }}
**> > x
**> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
**> [1,] 0 -14 -15 -16 -16 -23 -37 -51 -67 -79
**> [2,] 14 0 -1 -2 -2 -9 -23 -37 -53 -65
**> [3,] 15 1 0 -1 -1 -8 -22 -36 -52 -64
**> [4,] 16 2 1 0 0 -7 -21 -35 -51 -63
**> [5,] 16 2 1 0 0 -7 -21 -35 -51 -63
**> [6,] 23 9 8 7 7 0 -14 -28 -44 -56
**> [7,] 37 23 22 21 21 14 0 -14 -30 -42
**> [8,] 51 37 36 35 35 28 14 0 -16 -28
**> [9,] 67 53 52 51 51 44 30 16 0 -12
**> [10,] 79 65 64 63 63 56 42 28 12 0
**> > averank
**> [1] 15 29 30 31 31 38 52 66 82 94
**>
**>
**>
**> ----- Original Message -----
**> From: "IAIN GALLAGHER" <iaingallagher@btopenworld.com>
**> To: "Martin Henry H. Stevens" <HStevens@MUOhio.edu>
**> Cc: <r-help@stat.math.ethz.ch>
**> Sent: Monday, October 17, 2005 2:29 PM
**> Subject: Re: [R] Dunn's post hoc test
**>
**>
**> > Thanks for your reply Hank. It's not really what I'm
**> > after (though it's good to know).
**> >
**> > For the test ( as described in Statistics for the
**> > Biosciences by W. Gardiner. Prentice Hall, 1997) I
**> > have to rank my groups, calculate the average rank,
**> > then subtratc each average rank from every other. Any
**> > value greater than the test statistic is significant.
**> >
**> > eg average rank difference table:
**> >
**> > 2 5 8 9
**> > ---|------------------
**> > 2 - 3 6 7
**> > |
**> > 5 - - 3 4
**> > |
**> > 8 - - - 1
**> > |
**> > 9 - - - -
**> > |
**> >
**> > I can't get my head around writing an algorithm for
**> > this if I have a vector of average ranks eg averank<-
**> > c(2,5,8,9).
**> >
**> > I know I can address the vector by index and that this
**> > is probably the correct route but I can't get the
**> > indexing algorithm right!
**> >
**> > I'm sure someone will point out somethng simple and
**> > I'll kick myself but the help would be appreciated.
**> >
**> > Thanks again.
**> >
**> > Iain Gallagher
**> >
**> > --- "Martin Henry H. Stevens" <HStevens@MUOhio.edu>
**> > wrote:
**> >
**> > > I don't know Dunn's rank test, but the following
**> > > substracts each of
**> > > the sums of averanks from the next rank.
**> > >
**> > > cumsum(averank)[-length(averank)] - averank[-1]
**> > >
**> > > Hank
**> > >
**> > > On Oct 17, 2005, at 4:30 AM, Iain Gallagher wrote:
**> > >
**> > > > Hi Everyone.
**> > > >
**> > > > I am rather new to R and I've been trying to
**> > > implement a function to
**> > > > carry out the above test. For a couple of days now
**> > > I've been stuck on
**> > > > how to generate average rank differences.
**> > > >
**> > > > Say I have a vector of average ranks:
**> > > >
**> > > > averank<- c(2,5,9,12)
**> > > >
**> > > > I would like to subtract averank[1] from
**> > > averank[2], averank[1] and
**> > > > averank[2] from averank[3] and averank[1],
**> > > averank[2] and averank[3]
**> > > > from averank[4] etc (I know the syntax is wrong
**> > > here... it's just for
**> > > > illustration) but I can't work out how to do it.
**> > > >
**> > > > Ideally I would like to generate an array showing
**> > > the differences
**> > > > between the average ranks so I could tell at a
**> > > glance which ones were
**> > > > greater than my critical value
**> > > >
**> > > > I've been looking at loops etc but it's a little
**> > > beyond me at the
**> > > > moment. Thanks for any suggestions.
**> > > >
**> > > > Iain Gallagher
**> > > > IIIR
**> > > > Edinburgh University
**> > > >
**> > > > ______________________________________________
**> > > > R-help@stat.math.ethz.ch mailing list
**> > > > https://stat.ethz.ch/mailman/listinfo/r-help
**> > > > PLEASE do read the posting guide!
**> > > http://www.R-project.org/posting-
**> > > > guide.html
**> > > >
**> > >
**> > > Dr. Martin Henry H. Stevens, Assistant Professor
**> > > 338 Pearson Hall
**> > > Botany Department
**> > > Miami University
**> > > Oxford, OH 45056
**> > >
**> > > Office: (513) 529-4206
**> > > Lab: (513) 529-4262
**> > > FAX: (513) 529-4243
**> > > http://www.cas.muohio.edu/~stevenmh/
**> > > http://www.muohio.edu/ecology/
**> > > http://www.muohio.edu/botany/
**> > > "E Pluribus Unum"
**> > >
**> > >
**> >
**> > ______________________________________________
**> > R-help@stat.math.ethz.ch mailing list
**> > https://stat.ethz.ch/mailman/listinfo/r-help
**> > PLEASE do read the posting guide!
**> http://www.R-project.org/posting-guide.html
**> >
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
**>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Tue Oct 18 08:36:32 2005

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