[R] NA's?

[Bill.Venables@csiro.au]

is.na(diag(M)) <- TRUE

cmeans <- colMeans(M, na.rm = TRUE)
csd <- apply(M, 2, sd, na.rm = TRUE)
cvar <- csd ^2

(or

cvar <- apply(M, 2, var, na.rm = TRUE)

)

Using 'kmeans' on a matrix but 'ignoring the diagonal entries' just
doesn't make sense as it stands, so I can't help you there.

V.

-----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 3:48 PM
To: r-help at stat.math.ethz.ch
Subject: RE: [R] NA's?


I am sorry about that.


I like to do column mean, sd, var

as well as kmeans on the matrix

does this  na.rm = TRUE work for such fuctions and only the diagonal is 
ignored?

>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?
>
>V.
>
>-----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
>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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