vb_eeginfo_get_channel_number

 return channel number from EEGinfo struct

 [usage]
   [Nchannel] = vb_eeginfo_get_channel_number(eeginfo, active_swt)

 [input]
      eeginfo : <required> <<struct>> EEG header information
   active_swt : <optional> <<boolean>> [false]
              :  switch to return whether all the channels or only active
              :   true) only active channels
              :  false) all the channels

 [output]
     Nchannel : number of channel

 [note]
    target channel is sensor channels except for external channels

 [history]
   2007-08-02 (Sako) initial version
   2008-04-15 (Sako) added active_swt

 Copyright (C) 2011, ATR All Rights Reserved.
 License : New BSD License(see VBMEG_LICENSE.txt)

0001 function [Nchannel] = vb_eeginfo_get_channel_number(eeginfo, active_swt)
0002 % return channel number from EEGinfo struct
0003 %
0004 % [usage]
0005 %   [Nchannel] = vb_eeginfo_get_channel_number(eeginfo, active_swt)
0006 %
0007 % [input]
0008 %      eeginfo : <required> <<struct>> EEG header information
0009 %   active_swt : <optional> <<boolean>> [false]
0010 %              :  switch to return whether all the channels or only active
0011 %              :   true) only active channels
0012 %              :  false) all the channels
0013 %
0014 % [output]
0015 %     Nchannel : number of channel
0016 %
0017 % [note]
0018 %    target channel is sensor channels except for external channels
0019 %
0020 % [history]
0021 %   2007-08-02 (Sako) initial version
0022 %   2008-04-15 (Sako) added active_swt
0023 %
0024 % Copyright (C) 2011, ATR All Rights Reserved.
0025 % License : New BSD License(see VBMEG_LICENSE.txt)
0026 
0027 % --- CHECK ARGUMENTS --- %
0028 if ~exist('eeginfo', 'var'), eeginfo = []; end
0029 if ~exist('active_swt', 'var'), active_swt = []; end 
0030 [eeginfo, active_swt] = inner_check_arguments(eeginfo, active_swt);
0031 
0032 % --- MAIN PROCEDURE --------------------------------------------------------- %
0033 %
0034 if ~vb_info_active_channel_is_valid(eeginfo)
0035   ChannelLabel = vb_eeginfo_get_channel_label(eeginfo);
0036   Nchannel = length(ChannelLabel);
0037   return;
0038 end
0039 
0040 if ~active_swt
0041   ChannelLabel = vb_eeginfo_get_channel_label(eeginfo);
0042   Nchannel = length(ChannelLabel);
0043   return;
0044 end
0045 
0046 active_list = vb_info_get_active_channel(eeginfo);
0047 Nchannel = length(find(active_list==1));
0048 return;
0049 %
0050 % --- END OF MAIN PROCEDURE -------------------------------------------------- %
0051 
0052 % --- INNER FUNCTIONS -------------------------------------------------------- %
0053 %
0054 % --- inner_check_arguments()
0055 %
0056 function [eeginfo, active_swt] = inner_check_arguments(eeginfo, active_swt)
0057 func_ = mfilename;
0058 
0059 if isempty(eeginfo)
0060   error('(%s)eeginfo is a required parameter', func_);
0061 end
0062 
0063 if isempty(active_swt)
0064   % return all the channel
0065   active_swt = false;
0066 end
0067 
0068 if ~isfield(eeginfo, 'Nchannel')
0069   eeginfo.Nchannel = 0;
0070 end
0071 return;
0072 %
0073 % --- end of inner_check_arguments()
0074 %
0075 % --- END OF INNER FUNCTIONS ------------------------------------------------- %
0076 
0077 % --- END OF FILE --- %