[R] matrix indexing

[Philippe Grosjean]

This is really elementary indexing in S language:

matA[matB]

Best,

Philippe Grosjean

tom wright wrote:
> Can someone please give me a pointer here.
> I have two matrices
> 
> matA
> 	A	B	C
> 1	5	2	4
> 2	2	4	3
> 3	1	2	4
> 
> matB
> 	A	B	C
> 1	TRUE	FALSE	TRUE
> 2	FALSE	TRUE	TRUE
> 3	FALSE	FALSE	FALSE
> 
> how do I extract all the values from matA where the coresponding entry
> in matB == TRUE (or FALSE), perferably in vector form.
> 
> Many thanks
> tom
> 
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