CODEWITHSUNDEEP
matlabindexingstruct
Simon
Simon

Reputation: 85

Matlab accessing structures

I am trying to access data that are stored in structures in matlab. Having many files I am trying to make the process automatic, however I have a problem in accessing the struct using the structure name (given that it is a string). Also, storing the structure in a variable (as shown below) does not work either, because matlab attaches the whole structure to the variable. Does anybody have an idea on how to do this?

%Initialize variables
Data_Struct = load(dirData(1).name);
file_id = fieldnames(Data_Struct);
data = Data_Struct.Trajectories;

Here a screenshot of the struct containing the data enter image description here

Upvotes: 0

Views: 85

Answers (2)

l.fabbrini
l.fabbrini

Reputation: 101

The trick here is to exploit the fact that you can acces to a structure field by its name string as:

name = 'Trajectories'
value = Data_Struct.(name)

So, in your case, to get unrolled values as Cell Array you can use:

%%Little example copying some of your structure
Data_Struct.Trajectories.Labelled = zeros(10);
Data_Struct.Analog = zeros(10);
Data_Struct.FrameRate = 300;

[UnrolledCell] = getUnrolledVal(Data_Struct,[]);
display(UnrolledCell)

UnrolledCell =

3×2 cell array

'Labelled'     [10×10 double]
'FrameRate'    [         300]
'Analog'       [10×10 double]

Here the getUnrolledVal function is simply:

function [UnrolledCell] = getUnrolledVal(struct_in,UnrolledCell)
fields_list = fieldnames(struct_in);
for i=1:length(fields_list)
    field = fields_list{i};
    if isstruct(struct_in.(field))
        UnrolledCell = getUnrolledVal(struct_in.(field),UnrolledCell);
    else
        UnrolledCell = [UnrolledCell; {field} {struct_in.(field)}];
    end
end

end

Upvotes: 2

amahmud
amahmud

Reputation: 434

The file name is changing every time so you need to get the it correctly when loading a new struct. 

Data_Struct = load(dirData(1).name);

After this line, 

name = fieldnames(Data_Struct);

This will give you the unique name of your file. Finally,

data = Data_Struct.(name{1}).Trajectories.Labelled.(name of the data matrix)

Upvotes: 2

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