MATLAB: Loading large MAT files which are saved using “Save As” in Workspace gives error “File is corrupt”

MATLAB

In MATLAB Workspace, right click on the variable which you want to save and select "Save As". When you load the file again using "load" it gives the following error:

>> load('using_SaveAs.mat')

Error using load Unable to read MAT-file C:\Test\using_SaveAs.mat.

File might be corrupt

Best Answer

When you right click a variable in MATLAB Workspace and click "Save As", MATLAB runs the saving process in the background. Since the process is running in the background, we would have no way to know if the process is completed or not.

Loading a MAT file which is still being saved in the background or which was interrupted half way through because of closing MATLAB, results in the error.

Instead of using "Save As" in MATLAB Workspace, you can work around this issue by using the "save" command from the MATLAB Command Window.

For example, if you want to save the variable "April8Data" in the file "April8Data.mat" use the following command:

>>save('April8Data.mat', 'April8Data', '-v7.3')

Also be sure to use the '-v7.3' flag when your variable size is >2GB.

Related Solutions

MATLAB: How to load a single variable from a structure

If you have many variables in a MAT file, among which the structure of interest is also contained, there is no way to load only a single member of this structure into the workspace. For example, consider the following contents in the MAT file "sample.mat":

var1
var2
var3
structureVar

where "structureVar" contains the following:

sVar1
sVar2

Say we would like to load only "sVar1" into our workspace from "sample.mat". Currently, there is no way to do this. This is described in the "Limitations" section of the "matfile" documentation.

https://www.mathworks.com/help/matlab/ref/matfile.html#bt2ft8s-6

A workaround is to save the structure as an independent MAT file, and load members of the structure as needed. This is documented in "Variables" section of the "save" documentation:

https://www.mathworks.com/help/matlab/ref/save.html#btox10b-1-variables

For example, save "structureVar" as "structureVarMatFile.mat" when it is in the workspace using the following command:

>> save('structureVarMatFile','-struct','structureVar');

Now, you can load only "sVar1" if needed, using the following command:

>> load('structureVarMatFile','sVar1');

MATLAB: How to automate “Save As” dialog box when using “web” command to download from websites

To automate this, you can use the "websave" command.

As an example,

% download_url is the url you wish to download from
% file_name is the file you want the download to be saved to
% output_filename is the relative location of the file after it has been saved. 
>> output_filename = websave(file_name, download_url);

To learn more about the "websave" command, please visit the following documentation link :

https://www.mathworks.com/help/matlab/ref/websave.html

Best Answer

Related Solutions

MATLAB: How to load a single variable from a structure

MATLAB: How to automate “Save As” dialog box when using “web” command to download from websites

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