Assign multidimensional array 'slice' or 'chunk'

What’s the best way to assign
A(:, :, x1, x2, , xn)
to a given array, where
x = [x1, x2, , xn]
is a vector whose length is arbitrary (but matches the relevant dimensions of A)?

回答(1 个)

Use sub2ind. However, your vector will have to be repmat'ed for each colon in your indexing. e.g.:
x = [4, 7, 8]
A = reshape(1:5*6*7*8*9, [5, 6, 7, 8, 9]);
%indexing wanted: A(:, :, x1, x2, x3)
[idx1, idx2] = ndgrid(1:size(A, 1), 1:size(A, 2)); %generate all valid indices for the 1st two colons, put all colons into the ndgrid call
idxx = arrayfun(@(v) repmat(v, size(idx1), 1), x, 'UniformOutput', false); %repmat each x value into shape of colon index matrices and transform into cell array
result = A(sub2ind(size(A), idx1, idx2, idxx{:}))
isequal(result, A(:, :, 4, 7, 8))

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