Dynamic Naming of Matlab Function

Question

I currently have a MATLAB function that looks like this:

function outfile=multi_read(modelfrom,modelto,type)

models=[modelfrom:1:modelto];
num_models=length(models);

model_path='../MODELS/GRADIENT/'

for id=1:num_models
    fn=[model_path num2str(models(id)) '/'];  %Location of file to be read
    outfile=model_read(fn,type);              %model_read is a separate function
end
end

The idea of this function is to execute another function model_read for a series of files, and output these files to the workspace (not to disk). Note that the output from model_read is a structure! I want the function to save the file to the workspace using sequential names, similar to typing:

file1=multi_read(1,1,x)
file2=multi_read(2,2,x)
file3=multi_read(3,3,x)
etc.

which would give file1, file2 and file3 in the workspace, but instead by recalling the command only once, something like:

multi_read(1,3,x)

which would give the same workspace output.

Essentially my questions is, how do I get a function to output variables with multiple names without having to recall the function multiple times.

Why not using a cell array? It gives you exactly what you need, but wrapped in one object. You will retrieve the outputs of multi_read by doing file{i}. — Acorbe
– Acorbe, Commented Nov 19, 2012 at 10:58
Apologies to those who have replied, but I should have mentioned that the output from the model_read funtion is a structure array. I have edited the question to reflect this. — heds1
– heds1, Commented Nov 19, 2012 at 12:35

Acorbe · Accepted Answer · 2012-11-19 11:32:01Z

2

As suggested in the comment I would try this approach which is more robust, at least IMHO:

    N = tot_num_of_your_files; %whatever it is          

    file = cellfun(@(i)multi_read(i,i,x),mat2cell(1:N,1,ones(1,N)),...
                         'UniformOutput' , false); %(x needs to be defined)

You will recover objects by doing file{i}.

edited Nov 19, 2012 at 11:32

answered Nov 19, 2012 at 11:20

Acorbe

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5 Comments

Florian Brucker Over a year ago

+1 for avoiding eval and providing a much cleaner solution.

Dennis Jaheruddin Over a year ago

Why do you mention that this approach is more robust?

Acorbe Over a year ago

@DennisJaheruddin, more robust with respect to what the OP suggests. Having N different variables with indexed names doesn't look robust to me. If N is big you need cycles to interact with such variables and thus run-time mechanisms to obtain the variable names.

heds1 Over a year ago

As per my amendments above, note that the output from model_read is a structure array. I can't seem to port your answer above to work with a structure array as output. For reference, N is ~50.

Acorbe Over a year ago

@heds1, the point still holds; cells are suitable to store heterogeneous data types. In other word each cell entry can be different, e.g. File{1} can be a struct and File{2} can be a matrix and so on, thus you can have structs in them. Does this look ok to you?

Dennis Jaheruddin · Accepted Answer · 2012-11-19 12:14:25Z

1

Here is code to do what you ask:

for i = 1:3
   istr=num2str(i)
   line = ['file' istr '= multi_read(' istr ', ' istr ', x)']
   eval(line)
end

Alternatively, here is code to do what you should want:

for i = 1:3
    file{i} = multi_read(i,i,x)
end

edited Nov 19, 2012 at 12:14

answered Nov 19, 2012 at 11:02

Dennis Jaheruddin

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1 Comment

heds1 Over a year ago

Thanks for your suggestions, but I am trying to avoid the use of eval. Second answer also works, but I think the one-liner of @Acorbe is more useful.

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