Message-ID: <3E8C6A07.5020807@pdf.com>
Date: 2003-04-03T17:06:15Z
From: Sundar Dorai-Raj
Subject: Index of item in matrix
Or more simply:
> set.seed(1)
> A <- array(rnorm(12), dim=c(3,4))
> which(round(A) == 1, arr.ind = TRUE)
row col
[1,] 2 2
[2,] 1 4
Though, the original post may need more clarification.
Sundar
Spencer Graves wrote:
> Satisfying what conditions?
>
> Does the following example help you get what you want?
>
> > set.seed(1)
> > A <- array(rnorm(12), dim=c(3,4))
> >
> > sel <- (round(A)==1)
> > sel
> [,1] [,2] [,3] [,4]
> [1,] FALSE FALSE FALSE TRUE
> [2,] FALSE TRUE FALSE FALSE
> [3,] FALSE FALSE FALSE FALSE
> > cbind(row(A)[sel],col(A)[sel])
> [,1] [,2]
> [1,] 2 2
> [2,] 1 4
>
> Spencer Graves
>
> John Janmaat wrote:
>
>> Hello All,
>>
>> Is there a fast way to find the index(row and column) of a point in a
>> matrix?
>>
>> Thanks,
>>
>> John.
>
>
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