From: Gabor Grothendieck <ggrothendieck_at_gmail.com>

Date: Wed 24 Jan 2007 - 16:06:16 GMT

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 and provide commented, minimal, self-contained, reproducible code. Received on Thu Jan 25 13:03:18 2007

Date: Wed 24 Jan 2007 - 16:06:16 GMT

I wonder if a list of matrices is the best representation? Do your matrices all have the same dimension as in:

TP <- list(matrix(c(1:3, NA), 2), matrix(c(NA, 1:3), 2))

# Then you could consider representing them as an array:

TPa <- array(unlist(TP), c(2,2,2))

# in which case its just

TPa[is.na(TPa)] <- 0

TPa

On 1/24/07, Doran, Harold <HDoran@air.org> wrote:

*> I have some matrices stored as elements in a list that I am working
**> with. On example is provided below as TP[[18]]
**>
**> > TP[[18]]
**> level2
**> level1 1 2 3 4
**> 1 79 0 0 0
**> 2 0 0 0 0
**> 3 0 0 0 0
**> 4 0 0 0 0
**>
**> Now, using prop.table on this gives
**>
**> > prop.table(TP[[18]],1)
**> level2
**> level1 1 2 3 4
**> 1 1 0 0 0
**> 2
**> 3
**> 4
**>
**> It is important for the zero's to retain their position as this matrix
**> will subsequently be used in some matrix multiplication and hence, must
**> be of dimension 4 by 4 so that is it conformable for multiplcation with
**> another matrix.
**>
**> In looking at the structure of the object resulting from prop.table I
**> see NaNs, and so I can do this
**>
**> > rr <- TP[[18]]
**> > rr[is.na(rr)] <- 0
**> > rr
**> level2
**> level1 1 2 3 4
**> 1 79 0 0 0
**> 2 0 0 0 0
**> 3 0 0 0 0
**> 4 0 0 0 0
**>
**> This is exactly what I want for each matrix. But, I have multiple
**> matrices stored within the list that need to be changed and so I am
**> trying to resolve this via lapply, but something is awry (namely the
**> user), but I could use a little help.
**>
**> I was thinking the following function should work, but it doesn't. It
**> reduces each matrix within the list to a 0.
**>
**> PP <- lapply(TP, function(x) x[is.na(x)] <- 0)
**>
**> Am I missing something obvious?
**>
*

> Harold

*>
**>
**> [[alternative HTML version deleted]]
**>
**> ______________________________________________
**> 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
**> and provide commented, minimal, self-contained, reproducible code.
**>
*

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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 and provide commented, minimal, self-contained, reproducible code. Received on Thu Jan 25 13:03:18 2007

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