Class specific data files in matlab - matlab

Question

I'm writing a matlab class which uses data from a .mat-file.
Is there any way I can place this data file inside the class directory structure and make it accessible only to my class?
I.e. I have a directory structure like this:
./MATLAB
+myPackage
#MyClass
MyClass.m
where MyClass.m looks like
classdef MyClass
methods
function y = getValue(obj, x)
load datafile.mat
y = interp1(datax, datay, x);
end
end
end
This works great as long as datafile.mat is in my working directory, but I'd like to move it to +myPackage/#MyClass/datafile.mat instead (or better yet +myPackage/datafile.mat). How would I make my class(es) find it there?

Answer 1

First, you may put the data file in a 'private' subfolder inside your directory structure:
./MATLAB
+myPackage
private
datafile.mat
#MyClass
MyClass.m
NB: This won't garantee that it is only accessible to your class, anyway it will be classified close to your class definition.
Then, you can find back data values like this in your method:
classdef MyClass
methods
function y = getValue(obj, x)
% Find back datafile name
localPath = fileparts(mfilename('fullpath'));
dataFilename = fullfile(localpath, '..', 'private', 'datafile.mat'); % '..' is to go up one folder, up to you to place th file somewhere else (e.g. under +MyPackage directly)
% Read file
data = load(dataFilename);
datax = data.datax;
datay = data.datay;
y = interp1(datax, datay, x);
end
end
end
EDIT: Example with Resources class
Here is an example with separate resource class to avoid loading file data each time getValue is called. I also added for the case you need to care if the file has been modified or not:
classdef Resources
methods(Static)
function [resource] = GetResource(name, careForUpdates)
%[
if (nargin < 2), careForUpdates = true; end
if (nargin < 1), error('Not enough input arguments.'); end
persistent cache;
if (isempty(cache)), cache = containers.Map('UniformValues', false); end
filename = Resources.GetFileName(name);
lastModified = dir(filename);
lastModified = datenum(lastModified.date);
if (~cache.isKey(name) || ...
(careForUpdates && (cache(name).LastModified < lastModified)))
data.LastModified = lastModified;
data.Value = load(filename);
cache(name) = data;
end
resource = cache(name).Value;
%]
end
end
methods(Static, Access=private)
function [fname] = GetFileName(name)
%[
persistent cache;
if (isempty(cache)), cache = containers.Map('UniformValues', false); end
if (~cache.isKey(name))
localpath = fileparts(mfilename('fullpath'));
switch(name)
case 'titi', cache(name) = fullfile(localpath, 'titi.mat');
case 'toto', cache(name) = fullfile(localpath, 'toto.mat');
case 'tata', cache(name) = fullfile(localpath, 'tata.mat');
otherwise, error('Resource `%s` is unknown', name)
end
end
fname = cache(name);
%]
end
end
end
This can be used like this
data = Resources.Get('titi');
Or, if not interested by file updates:
careForFileUpdates = false;
data = Resources.Get('titi', careForFileUpdates);