Helper function to process multiple channels at a time

src/pspm_multi_channel.m

@@ -0,0 +1,80 @@
+function [sts, channel_index] = pspm_multi_channel(fhandle, channels, varargin)
+% ● Description
+%   pspm_multi_channel applies the same pre-processing function to multiple 
+%   channels in the same data file. This works by calling the pre-processing 
+%   function multiple times and so does accelerate processing time. It 
+%   creates the required loop and handles any processing errors.
+% ● Format
+%   [sts, channel_index] = pspm_multi_channel(function, channels, argument1, argument2, ..., options) 
+% ● Arguments
+%            fhandle: [char or function handle] Preprocessing function
+%           channels: [char, vector, cell array] Channel specifications:
+%                     1. 'gaze' will be expanded to {'gaze_x_r', 'gaze_y_r', 
+%                     'gaze_x_l', 'gaze_y_l'}
+%                     2. Eyetracker channels without lateralisation
+%                     specification (_r or _l) will be expanded to include
+%                     both eyes (i.e. 'pupil' will be expanded to 
+%                     {'pupil_r', 'pupil_l'}, which work on the last
+%                     channel of this type.
+%                     3. Any other valid channel identifier of type 'char' 
+%                     will be expanded to all channels of this type in the file.
+%                     4. Any numerical vector or cell array will work on
+%                     the specified channels exactly.
+%     argument1, ...: all input arguments for the pre-processing function
+%            options: must always be specified as the last input argument
+% ● Output
+%                sts: Status determining whether the execution was
+%                     successful (sts == 1) or not (sts == -1)
+%      channel_index: Index of the generated channels. Any unsuccesful 
+%                     pre-processing call leads to a NaN index
+% ● History
+%   Written in 2024 by Dominik R Bach (Uni Bonn)
+% 
+
+%% 1 Initialise
+global settings;
+if isempty(settings)
+  pspm_init;
+end
+sts = -1;
+outchannel = NaN;
+
+%% 3 Expand channels
+if ischar(channels) 
+    if strcmpi(channels, 'gaze')
+        channels = {'gaze_x_r', 'gaze_y_r', 'gaze_x_l', 'gaze_y_l'};
+    elseif ismember(channels, settings.eyetracker_channels) 
+        [sts, eye] = pspm_find_eye(channels);
+        if sts < 1, return; end
+        if strcmpi(eye, '')
+            channels = {[channels, '_r'], [channels, '_l']};
+        end
+    end
+end
+
+if ischar(channels)
+    % all pre-processing functions take filename as first argument
+    fn = varargin{1};
+    [sts, infos, data, filestruct] = pspm_load_data(fn, channels);
+    if sts < 1, return; end
+    channels = num2cell(filestruct.posofchannels);
+elseif isnumeric(channels)
+    channels = num2cell(channels);
+elseif ~iscell(channels) 
+    warning('ID:invalid_input', 'Channels must be numeric, char or cell.')
+    return
+end
+
+%% 4 Process channels
+options = varargin{end};
+varargin(end) = [];
+for i_channel = 1:numel(channels)
+    options.channel = channels{i_channel};
+    [csts, outchannel] = feval(fhandle, varargin{:}, options);
+    if csts == 1
+        channel_index(i_channel) = outchannel;
+    else
+        channel_index(i_channel) = NaN;
+    end
+end
+sts = 1;