Re: [R] how to find indices of particular array elements

From: Martin Lam <tmlammail_at_yahoo.com>
Date: Mon 17 Oct 2005 - 21:29:00 EST


# create a 4x4 matrix with random values smallmatrix = matrix(runif(16)*10, ncol = 4, nrow = 4)

# get the row and column number of the item in the matrix with the highest value
which(smallmatrix == max(smallmatrix), arr.ind = 1)

HTH, Martin

> Dear R helpers,
>
> I have a largish matrix (1300 x 1300) and I wish to
> find the row and column
> numbers that identify particular elements whose
> values I know in advance
> (for example, the row and column numbers for the
> maximum value of the
> matrix).
>
> I have looked in the help manual and found the
> functions 'row' and 'col' for
> finding the indices of a matrix. But, I can't figure
> out how to use them to
> obtain the indices of the matrix element with
> maximum value, despite over an
> hour of trying!
>
> Many thanks for your help,
>
> Jonathan Williams
>
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>
                


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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 Mon Oct 17 21:36:31 2005

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