Descriptive statistics for tables

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,

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
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
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 at gene.com> wrote:

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 at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On

Behalf Of DAVID CAMACHO

Sent: Thursday, September 22, 2005 9:10 AM
To: r-help at 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.

Therefore, as a

result I want another table. I import every table,

and create

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

create a

list or a data frame and directly utilize some

functions

like sd( ) without success, because it calculate

sd for the

columns . Which kind of object should I create

in order to

utilize directly this kind of functions?  Should I

program it

throw for loops?

David