CODEWITHSUNDEEP
matlabstructnaming-conventions
user3813057
user3813057

Reputation: 911

Dynamically name a struct variable in MATLAB

I have several files "2011-01-01.txt", "2013-01-02.txt", "2015-02-01.txt", etc. I wish to create a struct variable for each of the file such that (the values are made up): 

machine20110101.size=[1,2,3];
machine20110101.weight=2345;
machine20110101.price=3456;

machine20130102.size=[2,3,4];
machine20130102.weight=1357;
machine20130102.price=123;

machine20150201.size=[1,2,4];
machine20150201.weight=1357;
machine20150201.price=123;

And,

save('f20110101.mat','machine20110101');
save('f20130102.mat','machine20130102') ;
save('f20150201.mat','machine20150201');

As we can see, the struct names are derived from the files' names. How can I construct the above struct variables?

I've searched for a while, but I didn't figure out how to use genvarname.

And these links (dynamic variable names in matlab, dynamic variable declaration function matlab, Dynamically change variable name inside a loop in MATLAB) didn't solve my problem.

I'm using MATLAB R2012b, so functions like matlab.lang.makeUniqueStrings defined after this version is unavailable.

Upvotes: 0

Views: 1221

Answers (2)

user3813057
user3813057

Reputation: 911

Besides @excaza's answer, I used the following approach:

machine.size = [1,2,3]; machine.price = 335; machine.weight = 234;

machineName = ['machine',the_date];

machineSet = struct(machineName,machine);

save(OutputFile,'-struct','machineSet',machineName);

Upvotes: 0

sco1
sco1

Reputation: 12214

Now that I'm in front of MATLAB, here's an example based on my comment above, utilizing dynamic field names with the filenames pruned using fileparts and regexprep in a cellfun call.

% Sample list for testing here, use uigetdir with dir or whatever method to
% get a list of files generically
filelist = {'C:\mydata\2011-01-01.txt', ...
                'C:\mydata\2012-02-02.txt', ...
                'C:\mydata\2013-03-03.txt', ...
                'C:\mydata\2014-04-04.txt', ...
                };
nfiles = length(filelist);

% Get filenames from your list of files
[~, filenames] = cellfun(@fileparts, filelist, 'UniformOutput', false);

% Prune unwanted characters from each filename and concatenate with 'machine'
prunedfilenames = regexprep(filenames, '-', '');
myfieldnames = strcat('machine', prunedfilenames);

% Generate your structure
for ii = 1:nfiles
    % Parse your files for the data, using dummy variables since I don't 
    % know how your data is structured
    loadedsize = [1, 2, 3];
    loadedweight = 1234;
    loadedprice = 1234;

    % Add data to struct array
    mydata.(myfieldnames{ii}).size = loadedsize;
    mydata.(myfieldnames{ii}).weight = loadedweight;
    mydata.(myfieldnames{ii}).price = loadedprice;
end

@patrik raises some good points in the comments. I think the more generic method he would like to see (please correct me if I'm wrong) goes something like this:

% Sample list for testing here, use uigetdir with dir or whatever method to
% get a list of files generically
filelist = {'C:\mydata\2011-01-01.txt', ...
                'C:\mydata\2012-02-02.txt', ...
                'C:\mydata\2013-03-03.txt', ...
                'C:\mydata\2014-04-04.txt', ...
                };
nfiles = length(filelist);

% Get filenames from your list of files
[~, filenames] = cellfun(@fileparts, filelist, 'UniformOutput', false);

% Prune unwanted characters from each filename and concatenate with 'machine'
prunedfilenames = regexprep(filenames, '-', '');
mytags = strcat('machine', prunedfilenames);

% Preallocate your structure
mydata = repmat(struct('tag', '', 'size', [1, 1, 1], 'weight', 1, 'price', 1), nfiles, 1);

% Fill your structure
for ii = 1:nfiles
    % Parse your files for the data, using dummy variables since I don't 
    % know how your data is structured
    loadedsize = [1, 2, 3];
    loadedweight = 1234;
    loadedprice = 1234;

    % Add data to struct array
    mydata(ii).tag = mytags{ii};
    mydata(ii).size = loadedsize;
    mydata(ii).weight = loadedweight;
    mydata(ii).price = loadedprice;
end

Upvotes: 0

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