Error in reading a dat file

Question

Millone 2015-6-3

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/222165-error-in-reading-a-dat-file

编辑： James Tursa 2015-6-3

I am trying to read a binary file that was written as following:

if success== true
    [row,col,v] = find(A);
    row = uint32(row);
    col = uint32(col);
    fwrite(fid,size(A),'uint32');
    fwrite(fid,nnz(A),'uint32');
for i = 1:size(v,1)
    fwrite(fid, row(i), 'uint32');
    fwrite(fid, col(i), 'uint32');
    fwrite(fid, v(i), 'double');
end
end

using:

n = fread(fid,1,'double')
dims = fread(fid,n,'double')
A = fread(fid,'double')
A = reshape(A,dims')
fclose(fid);

but I get an error: Error using reshape Size vector must have at least two elements. Error in sparse(line 10) A = reshape(A,dims')

How can I solve this problem? Any help will be appreciated. Thanks

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Answer 1

James Tursa 2015-6-3

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/222165-error-in-reading-a-dat-file#answer_181391

编辑：James Tursa 2015-6-3

在 MATLAB Online 中打开

How is fread supposed to know that you wrote uint32 values to the file unless you tell it? Read in the uint32 values as uint32, not double.

EDIT:

Maybe something like this (CAVEAT: I am not on a machine with MATLAB at the moment so this is untested)

size_A = fread(fid,[1 2],'uint32');
nnz_A = fread(fid,[1 1],'uint32');
row = zeros(nnz_A,1,'uint32');
col = zeros(nnz_A,1,'uint32');
v = zeros(nnz_A,1);
for i = 1:nnz_A
    row(i) = fread(fid, [1 1], '*uint32');
    col(i) = fread(fid, [1 1], '*uint32');
    v(i) = fread(fid, [1 1], 'double');
end

Then rebuild A from the pieces.

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Millone 2015-6-3

Thanks for your comment. It is progressing but now, after I changed to uint32 I have a new error. Error using reshape To RESHAPE the number of elements must not change.

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