[R] Index of item in matrix

[Spencer Graves]

Sundar's solution is better than mine unless the code must also work in 
S-Plus.

Spencer Graves

Sundar Dorai-Raj wrote:
> 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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>>
> 
>