[R] NA's?

Asha Jayanthi ashajayanthi at hotmail.com
Thu Mar 31 07:52:56 CEST 2005

i have not answered your query in the last mail.

I hoped na.omit(M) will just ingnore the diagonal elements. i learnt by 
practice that it removes the whole row which has atleast one NA!! (that is 
not the case in Perl)

Since I am bit new to R, i did not knew how to just ignore those elements in 

>From: <Bill.Venables at csiro.au>
>To: <ashajayanthi at hotmail.com>,<r-help at stat.math.ethz.ch>
>Subject: RE: [R] NA's?
>Date: Thu, 31 Mar 2005 11:42:05 +1000
>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?
>-----Original Message-----
>From: r-help-bounces at stat.math.ethz.ch
>[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Asha Jayanthi
>Sent: Thursday, 31 March 2005 11:22 AM
>To: r-help at 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
>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
>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
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