[R] Eaxct position of specific elements in array

[Gabor Grothendieck]

See ?row ?col

On Fri, Aug 1, 2008 at 1:42 PM, Ralph S. <ruffel1 at hotmail.com> wrote:
>
> Hi,
>
> I am trying to get the positions in array coordinates (needed later) of certain elements in an array but I am not sure how to get them.
>
> My array is Q and the condition is dt>dV, where dt and dV are arrays of exactly the same dimensions as Q.
>
> I know that I can extract the elements of Q by using Q[dt>dV] but I need the array position of where this happens.
>
> I don't see how to use the which() command since some elements given by that the condition are not unique
> ( I tried which(Q==Q[dt>dV] ,arr.ind=TRUE) but that gives me too many positions plus
> Warning message:
> In Q == Q[dt > dV] :
>  longer object length is not a multiple of shorter object length)
>
> Any help would be really appreciated!
>
> -Ralph
>
>
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