I have a big array (1024x1024x360) and I want to save it to a mat file. When I just try
A=rand(1024,1024,360)
save('filename.mat','A');
The variable is created in the workspace, the file is being created, but it remains empty...
I'm using Matlab 2012a on Win7-64 machine, Why is that happening?
Earlier versions of Matlab couldn't save variables larger than 2 GB. Your default save file format may be set to an older type even on newer versions of Matlab; my own install of R2013a seems to have come preset to v7, which won't save anything that big. You have two choices: either specify the format for this file using an extra flag:
save('filename.mat','A','-v7.3');
or change the default for all save files by running preferences and looking in the MAT-files area under General.
Related
I'm running a model that has a bunch of DLLs which read some .mat files.
When I use an old version of MATLAB (I think 2011a) to generate the files I get files that work okay, but when I create them with 2017a the files seem not to work with the same script.
I've used 2017 to read in the working 2011 file and then saved it, and these files also don't work.
I've also tried the above with the '-vXX' settings at all available values according to the help, with no success.
Example:
clear; load('v2011file.mat'); save('v2017copy.mat', '-v6', 'var1', 'var2', 'var3');
One thing that I have noticed between the two is that when they're selected in the "Current folder" browser, the preview always shows the 2017 files with the variable names in alphabetical order, regardless of the order that I saved them in, while the older 2011 file seems to maintain the order that they were saved. I can only assume that this is something related to a change in the way that files are saved - it might not be the problem but it does hint toward a change (it does this whether or not I include '-vXX' to use older formats).
It's probably worth noting that the 2011 files are created on XP, while the 2017 files are made on Windows 7.
Essentially I'm looking for anyone who might know whether it's possible for me to change the way the file is put together by MATLAB, rather than having to change the DLLs to accept a newer file.
It looks like I can work around the save order issue and have something that works by doing:
save('new2017file.mat', 'var1');
save('new2017file.mat', 'var3'. '-append');
save('new2017file.mat', 'var2', '-append');
Meaning I can put them in a specific order - I have to have the default save set to -v7 in preferences>general>.mat files too.
I wouldn't say no to a more elegant answer if there's one available though!
while trying to save a workspace variable it throws an error in matlab saying I need to switch to -v7.3. I am not sure how to resolve this error since the earlier versions dont support readtable function or xlsread function for an excel file.
You simply need to use one of these:
save('file.m','var1','var2',-v7.3);
save file.m var1 var2 -v7.3
Matlab will save data by default to an older format of .mat files. This format does not support variables larger than 2^31 bytes but can be read by old releases of Matlab (pre-R2006b). If you have large variables, you need to switch to format 7.3.
All of this is in the documentation from the save function. Type doc save and read.
I have two binary files that I'm trying to compare using Matlab's built-in function visdiff, but it only displays the first 2000 bytes as a default. Is there any way to force the comparison tool to display the entire contents of both files side by side?
Edit the file matlabroot\toolbox\shared\comparisons\private\bindiff.m, where matlabroot is your MATLAB installation directory. On line 149, you'll see it sets the variable MAXLEN to 2000. Change this to something bigger (even Inf seems to work).
You may need to type rehash toolboxcache after making this change, in order to get MATLAB to notice.
Please note:
As you're making a change to the MATLAB source, this is at your own risk (it seems fine to me though). Keep a backup of the file you've edited.
That truncation at 2000 bytes is there for a reason - comparing the whole of larger binary files does seem to take quite a while, so be patient. Maybe try gradually increasing MAXLEN, rather than going straight to Inf.
I only have R2011b available to me right now, so if you're on a newer version the file path and line number I mentioned above may have changed. It was very easy to trace through the code from visdiff to comparisons_private to bindiff though, so unless they've changed the deeper structure of the Comparisons Tool between 11b and now, it will probably be very similar.
I'm trying to open a .mat file in the windows environment but it is failing. It was created in a Unix environment. Also note that this file was first put in a .tar file first, ftp via binary method. The file opens in Unix and I don't think it was corrupted in any way.
The *.mat file format is platform agnostic. The OS does not matter.
There are a number of variants of the *.mat file which have been used, and older versions cannot always read formats saved with newer versions. You can save to an older version using flags available in the save command. These formats have been updated as the Matlab feature set has demanded a more flexible file format, and as other technologies have advanced, most notably HDF5 in the recent version.
Finally, the save command supports an ASCII formatted option. I suspect this is your current problem, based on your comment regarding the error message received.
To address your current problem:
First, check to see if the file is an ASCII file. The easiest way is to simply open it in notepat, wordpad, or even the matlab editor. If the file is text, then this becomes a file parsing problem, and the appropriate use of fscanf shoudl fix the problem.
If the file is actually a binary *.mat file then you probably have a Matlab version incompatability. Yuo can either go back to the source unix environment and save to an older version (eg save .... -v7) or update the Matlab version of the reading computer.
I have a matrix cube which I load in my program to read data from. The size of this .mat file is 2.8 GB. I am not being able to load it with the error of 'running out of memory'. Is there a way to fix this?
You can use the matfile class to work on ranges within variables inside MatLab files. See
Load and save parts of variables in MAT-files
Here's some additional discussion that discloses that this feature is new with R2011b.
If the size of the data exceeds the available memory on your machine, then you are in trouble - this is unavoidable. However, if you only want certain variables inside the .mat file you can try to load just those variables using the
load(filename, variables)
version of the load function. It really depends on the contents of your .mat file. If the file is 2.8GB and you need ALL of the variables in the file and your machine does not have enough memory to cope, your only option is to buy more RAM.
EDIT Apparently this answer is incorrect if you are running R2011b and above as explained in the answer of Ben Voight