saving variables in a single .mat file
显示 更早的评论
Hello,
I have 360 .mat files containing same variable in with different data (row vectors) each of size in(1x3800000) stored in them. They are of size 9.84GB (all 360 files).
Now I want to save them all in 1 .mat file as a matrix out(360x3800000).
How can I do it?
采纳的回答
ndiaye bara
2012-3-26
0 个投票
Try this code m=zeros(3800000,360); for k=1:360, eval(sprintf('load F*_%d.mat',k)); % F*=name of all your files .mat% eval(sprintf('y=F*_%d(:,1);',k)); disp(k); clear F* if k==1, m=y; else m=[m,y]; end end
save File m t %save the new file .mat
4 个评论
Jan
2012-3-26
Please format the code and avoid EVAL for this task. EVAL is really not useful here. The pre-allocation of m does not help also if you let the martrix grow inside the loop.
Creating a 3800000x360 doublke matrix will be a problem on a 4GB machine.
zozo
2012-3-26
zozo
2012-3-27
Jan
2012-3-27
Dear zozo, accepting an answer means, that it solves your problem.
Daniel and I have warned you that you cannot load a 11GB of data (360*3800000*8 byte per double) efficiently, if you have only 4GB of RAM. I assume you need 32GB RAM to work efficiently with such large data, 64GB is safer.
The above EVAL approach is cruel.
You currently did not specify in which format you want to store the data, DOUBLEs or SINGLEs, an integer type, as cell or matrix. Anyhow, I'm convinced, that it is the wrong approach due to the limited memory.
更多回答（2 个）
Jan
2012-3-26
0 个投票
Do you have a 64-bit Matlab version? How many RAM do you have installed? Do you want to store the values in one 360 x 3'800'000 array, a most likely more useful 3'800'000 x 360 array, of as separate vectors e.g. in a {1 x 360} cell. The later has the advantage, that it does not need a contiguos free block of memory.
4 个评论
zozo
2012-3-26
Sivakumaran Chandrasekaran
2012-3-26
Hi Jan,
I have a doubt in the mat file, which is present in image retrival project in file exchange of mathworks. It has 651 images in their database. The mat file has been splitted into two categories. files and Hists.. How to create two things in a mat file.
Regards,
siva
siva@sdatech.in
Jan
2012-3-26
4GB RAM is very lean for such a big chunk of data. If it is really necessary to keep all values in the RAM simultaneously, buy more RAM. Implementing workarounds to process the data in pieces will be more expensive.
Jan
2012-3-26
@Siva: Does you comment concern the current topic? If so, please explain the connection. If not, please delete the comment and post it as a new question - with more details. Thanks.
Daniel Shub
2012-3-26
In a comment to Jan you say you have 4 GB of RAM. Loading 9+ GB of data is going to bring your computer to a screeching halt.
Try and create an array of the required size and see what happens ...
x = randn(360, 38000000);
2 个评论
zozo
2012-3-26
Daniel Shub
2012-3-27
Why? Nobody wants a 1+GB data file. Leave the files small and load them as needed. I doubt there is much of a benefit of doing a single huge load.
类别
在 帮助中心 和 File Exchange 中查找有关 Workspace Variables and MAT Files 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
