edfread源码

 function [hdr, record] = edfread(fname, varargin)
 % Read European Data Format file into MATLAB
 %
 % [hdr, record] = edfread(fname)
 %         Reads data from ALL RECORDS of file fname ('*.edf'). Header
 %         information is returned in structure hdr, and the signals
 %         (waveforms) are returned in structure record, with waveforms
 %         associated with the records returned as fields titled 'data' of
 %         structure record.
 %
 % [...] = edfread(fname, 'assignToVariables', assignToVariables)
 %         Triggers writing of individual output variables, as defined by
 %         field 'labels', into the caller workspace.
 %
 % [...] = edfread(...,'desiredSignals',desiredSignals)
 %         Allows user to specify the names (or position numbers) of the
 %         subset of signals to be read. |desiredSignals| may be either a
 %         string, a cell array of comma-separated strings, or a vector of
 %         numbers. (Default behavior is to read all signals.)
 %         E.g.:
 %         data = edfread(mydata.edf,'desiredSignals','Thoracic');
 %         data = edfread(mydata.edf,'desiredSignals',{'Thoracic1','Abdominal'});
 %         or
 %         data = edfread(mydata.edf,'desiredSignals',[,,:]);
 %
 % FORMAT SPEC: Source: http://www.edfplus.info/specs/edf.html SEE ALSO:
 % http://www.dpmi.tu-graz.ac.at/~schloegl/matlab/eeg/edf_spec.htm
 %
 % The first  bytes of the header record specify the version number of
 % this format, local patient and recording identification, time information
 % about the recording, the number of data records and finally the number of
 % signals (ns) in each data record. Then for each signal another  bytes
 % follow in the header record, each specifying the type of signal (e.g.
 % EEG, body temperature, etc.), amplitude calibration and the number of
 % samples in each data record (from which the sampling frequency can be
 % derived since the duration of a data record is also known). In this way,
 % the format allows for different gains and sampling frequencies for each
 % signal. The header record contains  + (ns * ) bytes.
 %
 % Following the header record, each of the subsequent data records contains
 % 'duration' seconds of 'ns' signals, with each signal being represented by
 % the specified (in the header) number of samples. In order to reduce data
 % size and adapt to commonly used software for acquisition, processing and
 % graphical display of polygraphic signals, each sample value is
 % represented as a -byte integer in 's complement format. Figure 1 shows
 % the detailed format of each data record.
 %
 % DATA SOURCE: Signals of various types (including the sample signal used
 % below) are available from PHYSIONET: http://www.physionet.org/
 %
 %
 % % EXAMPLE :
 % % Read all waveforms/data associated with file 'ecgca998.edf':
 %
 % [header, recorddata] = edfRead('ecgca998.edf');
 %
 % % EXAMPLE :
 % % Read records  and , associated with file 'ecgca998.edf':
 %
 % header = edfRead('ecgca998.edf','AssignToVariables',true);
 % % Header file specifies data labels 'label_1'...'label_n'; these are
 % % created as variables in the caller workspace.
 %
 % Coded // by Brett Shoelson, PhD
 % brett.shoelson@mathworks.com
 % Copyright  -  MathWorks, Inc.
 %
 % Modifications:
 % // Fixed a problem with a poorly subscripted variable. (Under certain
 % conditions, data were being improperly written to the 'records' variable.
 % Thanks to Hisham El Moaqet for reporting the problem and for sharing a
 % file that helped me track it down.)
 %
 % // Enabled import of a user-selected subset of signals. Thanks to
 % Farid and Cindy for pointing out the deficiency. Also fixed the import of
 % signals that had "bad" characters (spaces, etc) in their names.

 % HEADER RECORD
 %  ascii : version of this data format ()
 %  ascii : local patient identification
 %  ascii : local recording identification
 %  ascii : startdate of recording (dd.mm.yy)
 %  ascii : starttime of recording (hh.mm.ss)
 %  ascii : number of bytes in header record
 %  ascii : reserved
 %  ascii : number of data records (- if unknown)
 %  ascii : duration of a data record, in seconds
 %  ascii : number of signals (ns) in data record
 % ns *  ascii : ns * label (e.g. EEG FpzCz or Body temp)
 % ns *  ascii : ns * transducer type (e.g. AgAgCl electrode)
 % ns *  ascii : ns * physical dimension (e.g. uV or degreeC)
 % ns *  ascii : ns * physical minimum (e.g. - or )
 % ns *  ascii : ns * physical maximum (e.g.  or )
 % ns *  ascii : ns * digital minimum (e.g. -)
 % ns *  ascii : ns * digital maximum (e.g. )
 % ns *  ascii : ns * prefiltering (e.g. HP:.1Hz LP:75Hz)
 % ns *  ascii : ns * nr of samples in each data record
 % ns *  ascii : ns * reserved

 % DATA RECORD
 % nr of samples[] * integer : first signal in the data record
 % nr of samples[] * integer : second signal
 % ..
 % ..
 % nr of samples[ns] * integer : last signal

 if nargin >
     error('EDFREAD: Too many input arguments.');
 end

 if ~nargin
     error('EDFREAD: Requires at least one input argument (filename to read).');
 end

 [fid,msg] = fopen(fname,'r');
 if fid == -
     error(msg)
 end

 assignToVariables = false; %Default
 targetSignals = []; %Default
 for ii = ::numel(varargin)
     switch lower(varargin{ii})
         case 'assigntovariables'
             assignToVariables = varargin{ii+};
         case 'targetsignals'
             targetSignals = varargin{ii+};
         otherwise
             error('EDFREAD: Unrecognized parameter-value pair specified. Valid values are ''assignToVariables'' and ''targetSignals''.')
     end
 end

 % HEADER
 hdr.ver        = str2double(char(fread(fid,)'));
 hdr.patientID  = fread(fid,,'*char')';
 hdr.recordID   = fread(fid,,'*char')';
 hdr.startdate  = fread(fid,,'*char')';% (dd.mm.yy)
 % hdr.startdate  = datestr(datenum(fread(fid,,'*char')','dd.mm.yy'), 29); %'yyyy-mm-dd' (ISO 8601)
 hdr.starttime  = fread(fid,,'*char')';% (hh.mm.ss)
 % hdr.starttime  = datestr(datenum(fread(fid,,'*char')','hh.mm.ss'), 13); %'HH:MM:SS' (ISO 8601)
 hdr.bytes      = str2double(fread(fid,,'*char')');
 reserved       = fread(fid,);
 hdr.records    = str2double(fread(fid,,'*char')');
 hdr.duration   = str2double(fread(fid,,'*char')');
 % Number of signals
 hdr.ns    = str2double(fread(fid,,'*char')');
 for ii = :hdr.ns
     hdr.label{ii} = regexprep(fread(fid,,'*char')','\W','');
 end

 if isempty(targetSignals)
     targetSignals = :numel(hdr.label);
 elseif iscell(targetSignals)||ischar(targetSignals)
     targetSignals = find(ismember(hdr.label,regexprep(targetSignals,'\W','')));
 end
 if isempty(targetSignals)
     error('EDFREAD: The signal(s) you requested were not detected.')
 end

 for ii = :hdr.ns
     hdr.transducer{ii} = fread(fid,,'*char')';
 end
 % Physical dimension
 for ii = :hdr.ns
     hdr.units{ii} = fread(fid,,'*char')';
 end
 % Physical minimum
 for ii = :hdr.ns
     hdr.physicalMin(ii) = str2double(fread(fid,,'*char')');
 end
 % Physical maximum
 for ii = :hdr.ns
     hdr.physicalMax(ii) = str2double(fread(fid,,'*char')');
 end
 % Digital minimum
 for ii = :hdr.ns
     hdr.digitalMin(ii) = str2double(fread(fid,,'*char')');
 end
 % Digital maximum
 for ii = :hdr.ns
     hdr.digitalMax(ii) = str2double(fread(fid,,'*char')');
 end
 for ii = :hdr.ns
     hdr.prefilter{ii} = fread(fid,,'*char')';
 end
 for ii = :hdr.ns
     hdr.samples(ii) = str2double(fread(fid,,'*char')');
 end
 for ii = :hdr.ns
     reserved    = fread(fid,,'*char')';
 end
 hdr.label = hdr.label(targetSignals);
 hdr.label = regexprep(hdr.label,'\W','');
 hdr.units = regexprep(hdr.units,'\W','');
 disp('Step 1 of 2: Reading requested records. (This may take a few minutes.)...');
 if nargout >  || assignToVariables
     % Scale data (linear scaling)
     scalefac = (hdr.physicalMax - hdr.physicalMin)./(hdr.digitalMax - hdr.digitalMin);
     dc = hdr.physicalMax - scalefac .* hdr.digitalMax;

     % RECORD DATA REQUESTED
     tmpdata = struct;
     for recnum = :hdr.records
         for ii = :hdr.ns
             % Read or skip the appropriate number of data points
             if ismember(ii,targetSignals)
                 % Use a cell array for DATA because number of samples may vary
                 % from sample to sample
                 tmpdata(recnum).data{ii} = fread(fid,hdr.samples(ii),'int16') * scalefac(ii) + dc(ii);
             else
                 fseek(fid,hdr.samples(ii)*,);
             end
         end
     end
     hdr.units = hdr.units(targetSignals);
     hdr.physicalMin = hdr.physicalMin(targetSignals);
     hdr.physicalMax = hdr.physicalMax(targetSignals);
     hdr.digitalMin = hdr.digitalMin(targetSignals);
     hdr.digitalMax = hdr.digitalMax(targetSignals);
     hdr.prefilter = hdr.prefilter(targetSignals);
     hdr.transducer = hdr.transducer(targetSignals);

     record = zeros(numel(hdr.label), hdr.samples()*hdr.records);
     % NOTE: // Modified for loop below to change instances of hdr.samples to
     % hdr.samples(ii). I think this underscored a problem with the reader.

     disp('Step 2 of 2: Parsing data...');
     recnum = ;
     for ii = :hdr.ns
         if ismember(ii,targetSignals)
             ctr = ;
             for jj = :hdr.records
                 try
                     record(recnum, ctr : ctr + hdr.samples(ii) - ) = tmpdata(jj).data{ii};
                 end
                 ctr = ctr + hdr.samples(ii);
             end
             recnum = recnum + ;
         end
     end
     hdr.ns = numel(hdr.label);
     hdr.samples = hdr.samples(targetSignals);

     if assignToVariables
         for ii = :numel(hdr.label)
             try
                 eval(['assignin(''caller'',''',hdr.label{ii},''',record(ii,:))'])
             end
         end
         record = [];
     end
 end
 fclose(fid);