load_neuroscan.m

来自「绝对经典,老外制作的功能强大的matlab实现PLS_TOOBOX」· M 代码 · 共 1,009 行 · 第 1/4 页

%LOAD_NEUROSCAN  will load NeuroScan binary data file to a NeuroScan
%  structure. It supports file format AVG (average EEG), EEG (epoched
%  EEG), and CNT (continuous EEG). For continuous EEG format, it can
%  automatically distinguish whether data is from SynAmps module or is
%  from 100 and 330 KHz modules.
%
%  load_neuroscan will use file extension to tell whether it is an AVG,
%  an EEG, or a CNT format, unless the fileformat argument is provided.
%  If it can not find the proper file extension and the fileformat
%  argument is not provided, AVG data will be assumed.
%
%  Usage: ns = load_neuroscan(filename, [fileformat], [machineformat], ...
%					[cnt_start_time], [cnt_end_time])
%
%  ns - structure containing NeuroScan header fields SETUP & ELECTLOC,
%	and data. For epoched EEG data, a field SWEEP will be appended.
%	For continuous EEG data, fields TEEG & EVENT will be appended.
%
%  filename - NeuroScan data file name.
%
%  fileformat (optional) - Either 'AVG' (default), 'EEG', 'CNT', or 'CNT32'.
%			If it is empty, the default value will be used.
%
%  machineformat (optional) - Default is little-endian 'ieee-le'.
%			If it is empty, the default value will be used.
%
%    'ieee-le'     or 'l' - IEEE floating point with little-endian
%                           byte ordering
%    'ieee-be'     or 'b' - IEEE floating point with big-endian
%                           byte ordering
%    'vaxd'        or 'd' - VAX D floating point and VAX ordering
%    'vaxg'        or 'g' - VAX G floating point and VAX ordering
%    'cray'        or 'c' - Cray floating point with big-endian
%                           byte ordering
%    'ieee-le.l64' or 'a' - IEEE floating point with little-endian
%                           byte ordering and 64 bit long data type
%    'ieee-be.l64' or 's' - IEEE floating point with big-endian byte
%                           ordering and 64 bit long data type.
%
%  cnt_start_time (optional) - Only for continuous data file, you can 
%		specify the start time with unit in second that you 
%		want to extract. The rounded start time will be 
%		displayed in ns.start_time. By default, it starts 
%		at 0 second.
%
%  cnt_end_time (optional) - Only for continuous data file, you can 
%		specify the end time with unit in second that you 
%		want to extract. The rounded start time will be 
%		displayed in ns.end_time. By default, it ends at 
%		the end of data.
%
%  Notes:
%
%  1. This program assumed that the data were acquired from NeuroScan
%     version 3.0 and above.
%
%  2. There are two headers for all NeuroScan data file. General header
%     containing information that applies to all channels should be at
%     the beginning of a NeuroScan data file. The size of general header
%     is 900 bytes. Channel-specific header containing information that
%     pertains to particular channel should come after general header.
%     The size of channel-specific header is 75 bytes per channel.
%
%  3. Average Neuroscan data is stored as 4-byte floates in vectored
%     format for each channel. Each channel has a 5-byte header that
%     is no longer used. Thus, after SETUP & ELECTLOC, there is an
%     unused 5-byte header followed by SETUP.pnts of 4-byte floating
%     point numbers for the first channel; then a 5-byte header for
%     channel two followed by SETUP.pnts * size(float) bytes, etc.
%     Therefore, the total number of bytes after SETUP & ELECTLOC is:
%     SETUP.nchannels * ( 5 + SETUP.pnts * sizeof(float) ). To scale
%     a data point to microvolts, multiply by the channel-specific
%     calibration factor (i.e., for electrode j: channel[j]->calib)
%     and divided by the number of sweeps in the average (i.e., 
%     channel[j]->n);
%
%  4. According to CNTTOASC from Neuroscan, continuous Neuroscan data
%     type can be distinguished by SETUP.ContinuousType:
%
%     Type 0 or 1 means using 100/330KHz module for continuous files.
%     Data is stored as 2-byte integer after SETUP hdr and ELECTLOC 
%     hdr in multiplexed format. Each data scan consists of 
%     SETUP.nchannels points.
%
%     Type 3 means using SynAmps for continuous files. Data is stored
%     as 2-byte integer after SETUP hdr and ELECTLOC hdr, and is sent
%     in a blocked rather than multiplexed format. The size of block 
%     in byte is SETUP.ChannelOffset and the size of block in point
%     is SETUP.ChannelOffset/2. Since data is recorded continuously, 
%     block has to be concatenated each other.
%
%     To scale a data point to microvolts for channel j, first subtract
%     off the amplifier d.c.offset (if any) found in the variable
%     (ELECTLOC[j]->baseline). Then multiply by the sensitivity
%     (ELECTLOC[j]->sensitivity) times the channel specific scale factor
%     (ELECTLOC[j]->calib) devided by 204.8.
%
%     After continuous NeuroScan data, there is an Event Table.
%     At the beginning of the event table is a TEEG ("Tagged EEG")
%     structure that is defined in the sethead.h file. Following
%     this structure is the event table property. There are two
%     types of event tables - the first with a minimum of event
%     information, and the second with additional behavioral
%     information. The Teeg variable in the TEEG structure
%     indicates the type of event table. The number of events
%     in the event table can be calculated by dividing the size
%     variable in the TEEG structure by sizeof(EVENT1) or 
%     sizeof(EVENT2). The EVENT immediately follow the TEEG.
%
%  5. There are SETUP.compsweeps of data in an .EEG file. Each sweep
%     of data consists of a sweep header followed by the EEG data.
%     After the sweep header, data is stored as 2-byte integers in
%     multiplexed format. The scaling of .EEG data to microvolts is
%     identical to scaling of .CNT data above.
%
%  References:
%
%  1. Header structure can be found on: http://www.neuro.com/files/sethead.h
%  2. Appendix C of Document number 2204 Revision C, from Neuroscan
%  3. CNTTOASC from Neuroscan Customer Support Download Area
%  4. EEG2ASC from Neuroscan Customer Support Download Area
%
%  December 8, 2006 (jimmy): 
%	Neuroscan version 4.3 also has 32-bit acquisition
%	for its continuous data files. By default, it collects
%	16-bit integer data with the original SynAmp (SynAmp1).
%	With SynAmp2, it will collect 32-bit integer data. 
%	According to Neuroscan tech support, "this file format 
%	must be determined prior to reading the file, i.e. there
%	is no flag within the file itself to identify a file as 
%	32-bit". In order to read 32-bit data format, optional 
%	input "fileformat" of "load_neuroscan.m" function must
%	be specified to 'cnt32'. For example, you can load data
%	using: ns = load_neuroscan('myfile.cnt', 'cnt32'); Type
%	"help load_neuroscan" for the usage of "fileformat".
%	Because now the continuous data file can be very large,
%	you can specify cnt_start_time and cnt_end_time. Their
%	units are "second". For example, if you only want to
%	extract data from 0 second to 1.998 second, you can type:
%	ns = load_neuroscan('myfile.cnt', 'cnt', '', 0, 1.998);
%	The actual rounded start_time and end_time will be 
%	displayed in ns.start_time and ns.end_time.
%
%  - Jimmy Shen ([e-mail])
%
function ns = load_neuroscan(filename, varargin)

   if ~exist('filename','var'),
      error('Usage: ns=load_neuroscan(filename,[fileformat],[machineformat],[cnt_start_time],[cnt_end_time])');
   end

   if ~exist(filename,'file')
      error([filename, ': Can''t open file']);
   end

   ext = [];
   machineformat = '';
   start_time = [];
   end_time = [];

   if nargin > 1, ext = varargin{1}; end;
   if nargin > 2, machineformat = lower(varargin{2}); end;
   if nargin > 3, start_time = varargin{3}; end;
   if nargin > 4, end_time = varargin{4}; end;

   if isempty(ext) | ( ~strcmpi(ext,'avg') & ~strcmpi(ext,'eeg') & ... 
	~strcmpi(ext,'cnt') & ~strcmpi(ext,'cnt32') )

      [tmp1 tmp2 ext] = fileparts(filename);
      ext = ext(2:end);
   end

   if isempty(machineformat)
      machineformat = 'ieee-le';
   end

   fid = fopen(filename,'r',machineformat);

   %  General header containing information that applies to all channels
   %  should be at the beginning of a NeuroScan data file. The size of
   %  general header is 900 bytes.
   %
   if fid < 0,
      msg = sprintf('Cannot open file %s.',filename);
      error(msg);
   else
      ns.SETUP = read_SETUP(fid);		% general hdr
   end

   %  Channel-specific header containing information that pertains to
   %  particular channel should come after general header. The size of
   %  channel-specific header is 75 bytes per channel.
   %
   for i = 1:ns.SETUP.nchannels			% channel-specific hdr
      ns.ELECTLOC(i) = read_ELECTLOC(fid);
   end

   if strcmpi(ext, 'cnt') | strcmpi(ext, 'cnt32')	% read continuous data

      if ns.SETUP.savemode ~= 3
         error('Invalid continuous NeuroScan data');
      end

      if strcmpi(ext, 'cnt32')
         ns.precision = 'int32';
      else
         ns.precision = 'int16';
      end;

      ns.start_time = start_time;
      ns.end_time = end_time;

      [ns.data start_time end_time] = read_cnt(fid, ns);

      ns.start_time = start_time;
      ns.end_time = end_time;

      %  After continuous NeuroScan data, there is an Event Table.
      %  At the beginning of the event table is a TEEG ("Tagged EEG")
      %  structure that is defined in the sethead.h file. Following
      %  this structure is the event table property. There are two
      %  types of event tables - the first with a minimum of event
      %  information, and the second with additional behavioral
      %  information. The Teeg variable in the TEEG structure
      %  indicates the type of event table. The number of events
      %  in the event table can be calculated by dividing the size
      %  variable in the TEEG structure by sizeof(EVENT1) or 
      %  sizeof(EVENT2). The EVENT immediately follow the TEEG.

      ns.TEEG = read_TEEG(fid, ns.SETUP);	% tag for EEG types
         
      if ns.TEEG.Teeg == 1			% event type 1
         event_size = 8;
      elseif ns.TEEG.Teeg == 2			% event type 2
         event_size = 19;
      else
         error('Invalid Event table for continuous NeuroScan data');
      end

      for i = 1:floor(ns.TEEG.Size/event_size)	% read event table
         ns.EVENT(i) = read_EVENT(fid, ns);
      end
   elseif strcmpi(ext, 'eeg')

      %  There are SETUP.compsweeps of data in an .EEG file. Each sweep
      %  of data consists of a sweep header followed by the EEG data.
      %
      ns.data = zeros(ns.SETUP.nchannels, ns.SETUP.pnts*ns.SETUP.compsweeps);

      for i = 1:ns.SETUP.compsweeps		% read SWEEP head
         ns.SWEEP(i) = read_SWEEP(fid, ns.SETUP);

         %  After the sweep header, data is stored as 2-byte integers in