Automatically load a struct from a struct with a variable name

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Hi,
I am struggeling with hopefully only a small problem.
Maybe one of you could help me.
Problem:
I want to load automatically *.mat files with a variable name and get only a defined sub-struct out of it.
The loaded file is a struct and in this struct is a struct with a variable name according to the file-name.
And in this struct is another struct, which I need of course, with a fix fieldname.
Example:
  1. values = load (test1.mat) , result in workspace = values (struct)
  2. Content of values = struct with the name test1
  3. Content of test1 = 4 structs with fix field names (a, b, c, d)
Command for a file with a fix name is:
s = values.test1.a; % or .b, .c, .d
I am searching for a command to get only the contect of one sub-struct with the fix field name from a struct with a variable file-name.
And this should work without any further user input. (The path to the sub-struct should be generated automatically.)
Thank you.
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Accepted Answer

Stephen23
Stephen23 on 29 Nov 2022
Edited: Stephen23 on 29 Nov 2022
"The path to the sub-struct should be generated automatically"
Assuming that the MAT file contains exactly one variable (your structure), here is one simple approach that uses an intermediate cell array (the alternative is to fiddle around with fieldnames):
F = 'whateverfilename.mat'; % absolute/relative filename
C = struct2cell(load(F));
assert(isscalar(C),'Only one variable allowed!')
S = C{1}; % your structure
S.a
S.b
S.c
S.d
Note that accessing the data would be simpler and more robust if the structure name did not change with the filename. If you have the chance to redesign this data, just use a fixed variable name for the structure.

More Answers (1)

Jan
Jan on 29 Nov 2022
file = 'test1.mat'
[~, name] = fileparts(file);
values = load(file);
subStruct = values.(name);
a = subStruct.a;
etc.

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