[R] Conditional Operation in Matrix

[Ivan Calandra]

Hi,

Would that work for you?
d <- a-b
d[a==0 | b==0] <- 0

The output is as the one expected

HTH,
Ivan

Le 11/24/2010 15:54, Romildo Martins a écrit :
> Hello,
>
> I would like to perform the operation a - b, only for the non-zero values.
>
> Thanks a lot!
>
> RMB
>
>
>> a
>   0 0  0  0  4  0  0  0
>   0 0  0  0  0  3  0  0
>   0 0  0  0  0  0  0  3
>   0 0  0  0  0  0  4  0
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  0  0  0
>
>> b
>   0 4  4  4  4  4  4  4
>   0 0  4  4  4  4  4  4
>   0 0  0  4  4  4  4  4
>   0 0  0  0  4  4  4  4
>   0 0  0  0  0  5  5  5
>   0 0  0  0  0  0  5  5
>   0 0  0  0  0  0  0  5
>   0 0  0  0  0  0  0  0
>
>> a-b (expected)
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  -1  0  0
>   0 0  0  0  0  0  0  -1
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  0  0  0
>   0 0  0  0  0  0  0  0
>
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-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra at uni-hamburg.de

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