From: Dave Roberts <droberts_at_montana.edu>

Date: Sat 01 Oct 2005 - 03:33:52 EST

>>Thanks for your response,

*>>
*

*>>What I need is extremely simple. And I suppose there
*

*>>are so many way to do it.
*

*>>But as I have so many files to do it, I am looking for
*

*>>the simplest way (if possible)
*

*>>
*

*>>What I meant was that I have tables with the same
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*>>numbers of rows and columns, (square form, should I
*

*>>say?) like:
*

*>>
*

*>>2,5,7
*

*>>3,4,8
*

*>>2,9,3
*

*>>
*

*>>5,3,8
*

*>>2,5,5
*

*>>5,7,8
*

*>>
*

*>>But I have hundreds of this onces, (bigger once).
*

*>>Every one of this tables have the same size (columns,
*

*>>rows). And I want to obtain the sd, z-score, and
*

*>>p-value for the position [1,1], [1,2]....
*

*>>[2,1],[2,2]... etc etc. That is, to obtain a table
*

*>>with some simple descriptive statistics about all this
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*>>tables.
*

*>>I have try different methods, but I am no familiar
*

*>>with R. (by the way, I could not find the way to do
*

*>>loops with R)
*

*>>Any suggestion is welcome.
*

*>>David
*

*>>
*

*>>
*

*>>
*

*>>
*

*>>
*

*>>--- Berton Gunter <gunter.berton@gene.com> wrote:
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*>>
*

*>>
*

*>>>I don't know what a "quadratic, same size" table is
*

*>>>or what you mean. If you
*

*>>>do not get a satisfactory reply I suggest:
*

*>>>
*

*>>>1. Read and follow the posting guide at the end of
*

*>>>this message.
*

*>>>
*

*>>>2. In particular, provide a simple, reproducible
*

*>>>example to show what you
*

*>>>want to do and perhaps any error messages that you
*

*>>>may have received.
*

*>>>
*

*>>>
*

*>>>-- Bert Gunter
*

*>>>Genentech Non-Clinical Statistics
*

*>>>South San Francisco, CA
*

*>>>
*

*>>>
*

*>>>
*

*>>>>-----Original Message-----
*

*>>>>From: r-help-bounces@stat.math.ethz.ch
*

*>>>>[mailto:r-help-bounces@stat.math.ethz.ch] On
*

*>>>
*

*>>>Behalf Of DAVID CAMACHO
*

*>>>
*

*>>>>Sent: Thursday, September 22, 2005 9:10 AM
*

*>>>>To: r-help@stat.math.ethz.ch
*

*>>>>Subject: [R] Descriptive statistics for tables
*

*>>>>
*

*>>>>
*

*>>>>I have a lot (more than one hundred) of files with
*

*>>>
*

*>>>tables of
*

*>>>
*

*>>>>the same kind (quadratic, same size) and I want to
*

*>>>
*

*>>>obtain
*

*>>>
*

*>>>>some statistics for every position on them.
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*>>>
*

*>>>Therefore, as a
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*>>>
*

*>>>>result I want another table. I import every table,
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*>>>
*

*>>>and create
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*>>>
*

*>>>>an object read.table for it, then I have try to
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*>>>
*

*>>>create a
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*>>>
*

*>>>>list or a data frame and directly utilize some
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*>>>
*

*>>>functions
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*>>>
*

*>>>>like sd( ) without success, because it calculate
*

*>>>
*

*>>>sd for the
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*>>>
*

*>>>>columns . Which kind of object should I create
*

*>>>
*

*>>>in order to
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*>>>
*

*>>>>utilize directly this kind of functions? Should I
*

*>>>
*

*>>>program it
*

*>>>
*

*>>>>throw for loops?
*

*>>>>
*

*>>>>David
*

*>>>>
*

*>>>
*

*>>______________________________________________
*

*>>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
*

*>>
*

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Oct 01 03:46:01 2005

Date: Sat 01 Oct 2005 - 03:33:52 EST

If I understand the request, he wants to take a large number of matrices of identical size and stack them into a three dimentional array, and then calculate statistics on the the third dimension. If the multiple arrays have object names they can be combined into a 3-d array

> a <- matrix(rep(1,9),ncol=3) > b <- matrix(rep(2,9),ncol=3) > c <- matrix(rep(3,9),ncol=3) > z <- array(c(a,b,c),dim=c(3,3,3))

> z

, , 1

[,1] [,2] [,3]

[1,] 1 1 1 [2,] 1 1 1 [3,] 1 1 1

, , 2

[,1] [,2] [,3]

[1,] 2 2 2 [2,] 2 2 2 [3,] 2 2 2

, , 3

[,1] [,2] [,3]

[1,] 3 3 3 [2,] 3 3 3 [3,] 3 3 3

and then specific dimensions can be summarized

> mean(z[1,1,])

[1] 2

> sd(z[1,1,])

[1] 1

I don't know of any easy way to combine all the 2-d matrices other than listing them by name in a c() function in the array statement. If they were cleverly names perhaps a for loop could be used.

Dave

Jean Eid wrote:

> I do not totally understand your question as well. You seem to want a > descriptive statistic about a unitary number. What is the sd of a number? > or any other descriptive statictic. Maybe you mean for the columns or rows > or it could be that these are t-stats or z-stats that you need to get > p_values for them. In any case what I would do assuming that these tables > are in your env is the following > > sapply(ls(), function(x){ > nam <- paste(x,"_summary", sep="") > tt <- colMeans(get(x)) > assign(nam, tt, pos=1)}) > > The function above will output a number of tables with their original name > an extension _summary which contains the column means of the tables. > > If you have the tables in different files on your box you need to add a > read.table line above. and the function becomes > > sapply(dir(), function(x){ > > nam <- paste(x,"_summary", sep="") > assign(x, read.table(x)) > tt <- colMeans(x) > assign(nam, tt, pos=1)}) > > > HTH > > > On Fri, 30 Sep 2005, DAVID CAMACHO wrote: > >

>>Thanks for your response,

> > > ______________________________________________ > 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 Received on Sat Oct 01 03:46:01 2005

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