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How to extract number of matrices with all elements zero and the indexes of those matrices in a struct

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AKAYDIN
AKAYDIN 2023-1-16
评论： Voss 2023-1-17
Hi
I want to obtain the number of zero or nonzero matrices and their indexes in a struct like in the figure on the left. I am trying to check the cov named matrix in the right figure which are in all 1x1 struct cells on the left figure.
Thank you

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Voss
Voss 2023-1-16
Ran in:
% making up some data like yours:
gridcell_meancov = struct('grid',struct('mean',num2cell(rand(12,6)),'cov',squeeze(num2cell(randi([0 1],[2 2 12 6]),[1 2]))))
gridcell_meancov = struct with fields:
grid: [12×6 struct]
gridcell_meancov(1).grid
ans = 12×6 struct array with fields:
mean cov
% obtain which "cov" matrices are all zero:
cov_all_zero = ~cellfun(@(x)any(x,'all'),{gridcell_meancov(1).grid.cov})
cov_all_zero = 1×72 logical array
1 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 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0
% the number of all-zero cov matrices:
n_all_zero = nnz(cov_all_zero)
n_all_zero = 7
% the indexes of those all-zero cov matrices:
idx_all_zero = find(cov_all_zero)
idx_all_zero = 1×7
1 4 14 31 49 59 60
% the number of not-all-zero cov matrices:
n_not_all_zero = nnz(~cov_all_zero)
n_not_all_zero = 65
% the indexes of those not-all-zero cov matrices:
idx_not_all_zero = find(~cov_all_zero)
idx_not_all_zero = 1×65
2 3 5 6 7 8 9 10 11 12 13 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 32 33 34

更多回答（1 个）

Paul
Paul 2023-1-16
Ran in:
Hi Abdullah,
The Question use the term "cell" but it looks like the data only uses structures. If that's the case, then ....
Create some example data
gridcell_meancov(1).grid(1,1).mean = 0;
gridcell_meancov(1).grid(1,1).cov = zeros(2);
gridcell_meancov(1).grid(1,2).mean = 0;
gridcell_meancov(1).grid(1,2).cov = eye(2);
gridcell_meancov(1).grid(2,1).mean = 0;
gridcell_meancov(1).grid(2,1).cov = zeros(2);
gridcell_meancov(1).grid(2,2).mean = 0;
gridcell_meancov(1).grid(2,2).cov = eye(2);
The result
sum(arrayfun(@(S) all(S.cov==0,'all') ,gridcell_meancov(1).grid),'all')
ans = 2
If I've misinterpreted the arrangment of the data, then post a small example that illustrates the data you have.

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