How to access a particular array from a structure of arrays saved in a .mat file without loading the entire mat file

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Nadia A 2016-10-5

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编辑： Nadia A 2016-10-10

Hi

I have a .mat file which contain a structure which in turn has many fields and large data arrays. Sample file shown below:

y_struct = struct('yval',[],'time',[]);
y_struct.yval = struct('tag',{'y1value','y2value','y3value'},'data',{[],[],[]});   %  Defining structure to store the y array 
                                                                                %  and its deviations 
y_struct.time = t;
y_struct.yval(1).data = input;                                                        
y_struct.yval(2).data = y_struct.yval(1).data + 0.5;

Load command will save the entire mat file in memory. In my application, I want to access data fields with a particular tag(y_struct.yval(1).data). Is there a way to directly access this array element without having to load the entire .mat file? I read that using a matfile object we can access mat file elements but is it possible to access array index?

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Answer 1

KSSV 2016-10-5

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编辑：Walter Roberson 2016-10-5

Read the link:

https://in.mathworks.com/help/matlab/import_export/load-parts-of-variables-from-mat-files.html

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KSSV 2016-10-10

What error it shows?

Nadia A 2016-10-10

编辑：Nadia A 2016-10-10

在 MATLAB Online 中打开

It says field cannot be accessed. The mat file contains 3 (1x4) structures. tag1,tag2,tag3(each of dimension 1x4). When I try to access data field of tag1, it shows error

'Cannot index into 'tag1' because MatFile objects only support '()' indexing'

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