You could use 'do.call' with 'bind.array' (from S Poetry) or 'abind'
to convert your list of matrices into a three-dimensional array.

Patrick Burns

Burns Statistics
[EMAIL PROTECTED]
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")

David Kane wrote:

Is there a simple way to calculate summary statistics for all the
matrices or dataframes in a list? For example:



z <- list(matrix(c(2,2,2,2), ncol = 2), matrix(c(4,4,4,4), ncol = 2))
z


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

[[2]]
[,1] [,2]
[1,] 4 4
[2,] 4 4



I would like to calculate, for example, the mean value for each cell. I can do that the hard way as:



(z[[1]] + z[[2]]) / 2


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



But there must be an easier way. I am also interested in other statistics (like median and sd). Since all my matrices have the same attributes (especially row and column names), I would like to preserve those in the answer.

Thanks,

Dave Kane

In case it matters:



R.version


_ platform i686-pc-linux-gnu
arch i686 os linux-gnu system i686, linux-gnu status major 2 minor 1.0 year 2005 month 04 day 18 language R



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