Cell array construction operator

Question

Yro 2020-12-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/703457-cell-array-construction-operator

回答： Jan 2020-12-30

I want to use GNU Octave to run my simulation but I have the following problem with the following array,

for i = 1:length(ARRAY)
    
    find_fcn1{i,:} = find(ARRAY(:,1)==(ARRAY(i,1) + 1));
    find_fcn2{i,:} = find(ARRAY(:,2)==(ARRAY(i,2) + 1));
    find_fcn3{i,:} = find(ARRAY(:,1)==(ARRAY(i,1) - 1));
    find_fcn4{i,:} = find(ARRAY(:,2)==(ARRAY(i,2) - 1));
end

I get the following error when using Octave: <invalid dimension inquiry of a non-existent value>. How can I modify the cell array to be able to use Octave?.

Thanks in advance.

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Answer 1

Jan 2020-12-30

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/703457-cell-array-construction-operator#answer_586983

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Did you pre-allocate the cells before the loop?

n = length(ARRAY);
find_fcn1 = cell(n, 1);
find_fcn2 = cell(n, 1);
find_fcn3 = cell(n, 1);
find_fcn4 = cell(n, 1);
for i = 1:n
    find_fcn1{i} = find(ARRAY(:,1)==(ARRAY(i,1) + 1));
    find_fcn2{i} = find(ARRAY(:,2)==(ARRAY(i,2) + 1));
    find_fcn3{i} = find(ARRAY(:,1)==(ARRAY(i,1) - 1));
    find_fcn4{i} = find(ARRAY(:,2)==(ARRAY(i,2) - 1));
end

If this is working, the problem was hidden in "find_fcn1{i,:}": If this cell is not defined already, Ocatve cannot guess, how large the 2nd. dimension is. Because find() replies a vector, a "find_fcn1{i, 1}" would be sufficient also.