Reading a large binary file

Question

Dominik Rhiem 2023-10-18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2035334-reading-a-large-binary-file

评论： Dominik Rhiem 2023-10-19

I want to load a 8 GB binary data file into Matlab. My computer has 24 GB of RAM. It runs out of memory, despite me closing literally everything besides Matlab, and I don't understand why. The file should not take more than its size, right?

Code for loading is simply:

fd = fopen(['data.bin'], 'r');
data = fread(fd, 'int16');
fclose(fd);

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Answer 1

James Tursa 2023-10-18

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2035334-reading-a-large-binary-file#answer_1335959

编辑：James Tursa 2023-10-18

在 MATLAB Online 中打开

Try

data = fread(fd, '*int16');

When you use 'int16' for the type to read, MATLAB reads as int16 and then converts to double (four times the memory). When you use '*int16', MATLAB keeps the type as int16. E.g.,

% Create a small sample file
fid = fopen('junk.bin','wb');
fwrite(fid,int16(4),'int16');
fclose(fid);
% read it with 'int16'
fid = fopen('junk.bin','rb');
x = fread(fid,'int16')
x = 4
class(x) % double, not what you wanted
ans = 'double'
% read it with '*int16'
frewind(fid);
x = fread(fid,'*int16')
x = int16
    4
class(x) % int16, this is what you wanted
ans = 'int16'
fclose(fid);