[R] Re place values matrix

[Greg Snow]

Try something along these lines:

> mat <- matrix(0, 10, 10)
> x <- c(1,10,10,1)
> y <- c(1,1,10,10)
> z <- 1:4
> mat[ cbind(x,y) ] <- z
> mat


Hope this helps,

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of start
> Sent: Tuesday, November 18, 2008 8:55 AM
> To: r-help at r-project.org
> Subject: [R] Re place values matrix
>
>
> To replace particular values in a matrix we can use the following
> command.
>
> matrix[x,y] = value
>
> But what to do if I have a list of +- 1,000,000 values and associated
> x,y
> values.
> Is there an efficient way to replace my matrix with those values.
>
> My first idea was to replace x, y and values by vectors.......but that
> doesn't work.
> Value in this case can't be a vector :(. It results in a wrong
> replacement.
> It takes the last value of the matrix.........
>
>
> --
> View this message in context: http://www.nabble.com/Replace-values-
> matrix-tp20562113p20562113.html
> Sent from the R help mailing list archive at Nabble.com.
>
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