R help - Apr 2011 - extract cells by columns/rows from matrix

Hi All,

I have the following matrix Ufi (x by y):
> Ufin
      1 2 3 4 5 6 7 8 9 10
   1  0 0 0 0 0 0 0 0 0  0
   2  0 0 0 0 0 0 0 0 0  0
   3  0 0 0 0 0 0 0 0 0  0
   4  0 0 0 6 0 0 0 0 0  0
   5  0 0 0 0 0 0 0 0 0  0
   6  0 0 0 0 0 0 9 0 0  0
   7  0 2 0 0 0 0 0 0 0  0
   8  0 0 0 0 0 0 0 0 0  0
   9  0 0 0 0 0 0 0 1 0  0
   10 0 0 0 0 0 0 0 0 0  0

And I need to extract the values for x and for y of those cells with maximum
values:

First would be:

x=7; y=6

Second:

x=4; y=4

And so on... Any help?

Thanks!

Nic

hi All,

I have a matrix Ufi (x by y)

   1  2  3  4  5
1 0  0  0  0  3
2 0  0  0  9  0
3 0  2  0  0  3
4 0  0  1  0  0
5 0  1  0  0  0

And I need the x and y "coordinates" of those cells with maximum
values:

First:

x=4; y=2  (Value=9)

Second:

x=5; y=3  (value=3)

Any help?
THANKS!

Nic

which(data==max(data),arr.ind=TRUE)

gives you the indices of the largest element.

which(data==data[order(data)[2]],arr.ind=TRUE)

the indices of the second largest.

Best
Jannis

On 04/14/2011 10:23 PM, Nicolas Gutierrez wrote:
> hi All,
>
> I have a matrix Ufi (x by y)
>
>   1  2  3  4  5
> 1 0  0  0  0  3
> 2 0  0  0  9  0
> 3 0  2  0  0  3
> 4 0  0  1  0  0
> 5 0  1  0  0  0
>
> And I need the x and y "coordinates" of those cells with maximum
values:
>
> First:
>
> x=4; y=2  (Value=9)
>
> Second:
>
> x=5; y=3  (value=3)
>
> Any help?
> THANKS!
>
> Nic
>
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