RE: [R] NA's?

From: <Bill.Venables_at_csiro.au>
Date: Thu 31 Mar 2005 - 11:42:05 EST


Your message doesn't help us very much. You haven't said what kind of calculation it is you want to do, and that certainly matters. For example, for some kinds of computations the solution you started below would work fine:

> M <- matrix(1:16, 4, 4)
> is.na(diag(M)) <- TRUE
> M

     [,1] [,2] [,3] [,4]

[1,]   NA    5    9   13
[2,]    2   NA   10   14
[3,]    3    7   NA   15
[4,]    4    8   12   NA

> rowSums(M, na.rm = TRUE)

[1] 27 26 25 24
> colSums(M, na.rm = TRUE)

[1] 9 20 31 42

You can also use apply( ) with functions that will accept missing values (and ignore them) for computations on either the rows or the columns.

Hoping for a general mechanism that would somehow signal the diagonal values as values to be "ignored" in a general way is not a possibility. Just as a curiosity, what were you hoping that na.omit(M) would do?

V.

-----Original Message-----
From: r-help-bounces@stat.math.ethz.ch
[mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Asha Jayanthi Sent: Thursday, 31 March 2005 11:22 AM
To: r-help@stat.math.ethz.ch
Subject: [R] NA's?

I have a large matrix of data .

The size of the matrix ranges from 100 x 100 to 1000 x 1000

Now i have to do computations on that. And should not consider the diagonal
elements.

I tried setting diag(M) = NA and M = na.omit(M).

But this omits all the rows. I only want to omit that diagonal elements only
but consider the whole row.

diag(M) = 0 seems like a good option but this will affect my result.

How to proceed with this. How to just ignore some specific values. what if i
want to consider only the upper / lower triangular matrix

Asha

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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 Thu Mar 31 11:48:18 2005

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