Hi all
Suppose I have a dim=c(2,2,3) matrix A, say:
A[,,1]= a b c d
A[,,2]= e f g h
A[,,3]= i j k l
Suppose that I want to create a 2x2 matrix X, which picks elements from the above-mentioned submatrices according to an index matrix J referring to the "depth" dimension:
J=
1 3
2 3
In other words, I want X to be X= a j g l
since the matrix J says that the (1,1)-element should be picked from A[,,1], the (1,2)-element should be picked from A[,,3], etc.
I have A and I have J. Is there an expression in A and J that creates X?
Thanks
Juhana
[EMAIL PROTECTED]
-- Juhana Vartiainen
docent in economics Director, FIEF (Trade Union Foundation for Economic Research, Stockholm), http://www.fief.se gsm +46 70 360 9915 office +46 8 696 9915 email [EMAIL PROTECTED] homepage http://www.fief.se/staff/Juhana/index.html
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