datafile.m

The pattern recognition matlab toolbox

%DATAFILE Datafile class constructor. This is an extension of DATASET.
%
%    A = DATAFILE(DIRECTORY,TYPE,READCMD,P1,P2,P3, ...)
%    A = DATAFILE(DIRECTORY,READCMD,P1,P2,P3, ...)
%
% INPUT
%   DIRECTORY - Data directory
%   TYPE      - Datafile type (default 'raw')
%   READCMD   - Command (m-file) for reading files in DIRECTORY
%   P1,P2,P3  - Optional parameters of READCMD
%
% OUTPUT
%   A         - Datafile
%
% DESCRIPTION
% Datafiles prepare and enable the handling of datasets distributed over
% multiple files, i.e. all files of DIRECTORY. Datafiles inherit all
% dataset fields. Consequently, most commands defined on datasets also
% operate on datafiles with the exception of a number of trainable
% mappings. There are four types of datafiles defined:
% TYPE = 'raw' : Every file is interpreted as a single object in the
%                dataset. All objects in the same sub-directory of
%                DIRECTORY receive the name of that sub-directory as class
%                label. Files may be preprocessed before conversion to
%                dataset by FILTM. At conversion time they should have the
%                same size (number of features).
% TYPE = 'pre-cooked' : It is expected that READCMD outputs for all files a
%                dataset with the same label list and the same feature size.
% TYPE = 'half-baked' : All files in DIRECTORY should be mat-files,
%                containing a single dataset. All datasets should have the 
%                same label list and the same feature size.
% TYPE = 'mature' : This is a datafile directory constructed by SAVEDATAFILE. 
%                It executes all processing before creation.
% For all datafile types holds that execution of mappings (by FILTM or 
% otherwise and conversion to a dataset (by DATASET) is postponed as long as 
% possible. Commands are stored inside one of the datafile fields. 
% Consequently, errors might be detected at a later stage.
%
% The construction by DATAFILE still might be time consuming as for some types
% all files have to be checked. For that reason PRTools attempts to save a 
% mat-file with the DATAFILE definition in DIRECTORY. If it is encountered, it 
% is loaded avoiding a redefinition. 
%
% SEE ALSO
% DATAFILES, DATASETS, MAPPINGS, FILTM, SAVEDATAFILE