| % mergesacc() - handle temporal saccade clusters | |
| % | |
| % Usage: | |
| % >> sac = mergesacc(sac,x,mindist,mode) | |
| % | |
| % Inputs: | |
| % sac output of saccpar (size: nsac * 9 columns) | |
| % x eye position of corresponding data epoch | |
| % mindist minimum required distance (in samples) between detected | |
| % movements in order to treat them as separate saccades | |
| % (i.e. minimum allowed fixation duration) | |
| % mode [1,2,3, or 4] Specifies way in which saccade clusters | |
| % are treated: | |
| % 1: do nothing, keep all saccades | |
| % 2: only first saccade of each cluster is kept | |
| % 3: only largest saccade of each cluster is kept | |
| % 4: saccades of the cluster are merged into one (longer) sacc. | |
| % | |
| % Outputs: | |
| % sac modified sac, changed according to "mode" | |
| % % columns of [sac]: | |
| % 1: saccade onset (sample) | |
| % 2: saccade offset (sample) | |
| % 3: duration (samples) | |
| % 4: NaN (originally: delay between eyes in samples) | |
| % 5: vpeak (peak velocity) | |
| % 6: saccade distance | |
| % 7: saccade angle (based on distance) | |
| % 8: saccade amplitude | |
| % 9: saccade angle (based on amplitude) | |
| % | |
| % Note: This function is not part of the original algorithms proposed by | |
| % Engbert et al. (2003, 2006). It intends to solve the problem that | |
| % single eye movements may be detected as multiple saccades by microsacc, | |
| % binsacc, and saccpar. For example, overshoots towards the end of saccades | |
| % ("glissades") are frequently detected as a separate saccade events, even | |
| % though they are probably better regarded as part of the same movement. | |
| % One consequence of this can be extremely short fixation durations | |
| % (e.g. < 50 ms). | |
| % | |
| % Note: This function is experimental. | |
| % | |
| % See also: | |
| % smoothdata, vecvel, velthresh, microsacc_plugin, binsacc, saccpar | |
| % | |
| % Author: od | |
| % Copyright (C) 2009-2017 Olaf Dimigen & Ulrich Reinacher, HU Berlin | |
| % olaf.dimigen@hu-berlin.de | |
| % This program is free software; you can redistribute it and/or modify | |
| % it under the terms of the GNU General Public License as published by | |
| % the Free Software Foundation; either version 3 of the License, or | |
| % (at your option) any later version. | |
| % | |
| % This program is distributed in the hope that it will be useful, | |
| % but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| % GNU General Public License for more details. | |
| % | |
| % You should have received a copy of the GNU General Public License | |
| % along with this program; if not, write to the Free Software | |
| % Foundation, 51 Franklin Street, Boston, MA 02110-1301, USA | |
| function sac = mergesacc(sac,x,mindist,mode) | |
| if nargin < 4 | |
| error('\n%s() expects four inputs',mfilename) | |
| end | |
| % column with sacc. size information | |
| % col. 6: distance (sacc. endpoint minus startpoint) | |
| % col. 8: amplitude (max minus min in full sacc. trajectory) | |
| AMPCOL = 6; | |
| nsac = size(sac,1); | |
| keep = true(nsac,1); % vector of saccades to keep | |
| % determine temporal distance to preceding saccade | |
| if nsac > 1 | |
| tempdist = [NaN; sac(2:end,1)-sac(1:end-1,2)]; | |
| else | |
| tempdist = NaN; | |
| end | |
| % get index of saccades that form temporal clusters | |
| ix_close = find(tempdist < mindist); | |
| if ~isempty(ix_close) | |
| % get beginning, end, length of saccade clusters | |
| clustlist = findsequence2(ix_close); | |
| clustlist(:,1) = clustlist(:,1)-1; % include first saccade | |
| clustlist(:,3) = clustlist(:,3)+1; % update cluster length | |
| % go tru saccade clusters | |
| for n = 1:size(clustlist,1) | |
| ix = clustlist(n,1):clustlist(n,2); | |
| % how to treat saccade clusters? | |
| switch mode | |
| case 1 | |
| % do nothing | |
| return | |
| case 2 | |
| % keep first saccade of each cluster | |
| keep(ix(2):ix(end)) = 0; | |
| case 3 | |
| % keep largest saccade of each cluster | |
| keep(ix) = 0; | |
| [tmp,ix_max] = max(sac(ix,AMPCOL)); | |
| keep(ix(ix_max)) = 1; | |
| case 4 | |
| % merge all saccades of cluster into one movement | |
| newsac(1) = sac(ix(1),1); % onset | |
| newsac(2) = sac(ix(end),2); % offset | |
| newsac(3) = newsac(2)-newsac(1)+1; % duration | |
| newsac(4) = NaN; % originally: delay between eyes | |
| % saccade peak velocity (vmax), here: max of individual vmax'es of cluster saccades | |
| newsac(5) = max(sac(ix,5)); | |
| % alternative: go back to raw data to get overall vmax | |
| % newsac(5) = max( sqrt( vel(newsac(1):newsac(2),1).^2 + vel(newsac(1):newsac(2),2).^2 ) ); | |
| % saccade distance (dx,dy) & angle (based on distance) | |
| dx = x(newsac(2),1)-x(newsac(1),1); | |
| dy = x(newsac(2),2)-x(newsac(1),2); | |
| newsac(6) = sqrt(dx.^2+dy.^2); | |
| newsac(7) = atan2(dy,dx); % angle1 | |
| % saccade amplitude (dX,dY) & angle (based on amplitude) | |
| i = newsac(1):newsac(2); | |
| [minx, ix1] = min(x(i,1)); | |
| [maxx, ix2] = max(x(i,1)); | |
| [miny, iy1] = min(x(i,2)); | |
| [maxy, iy2] = max(x(i,2)); | |
| dX = sign(ix2-ix1)*(maxx-minx); | |
| dY = sign(iy2-iy1)*(maxy-miny); | |
| newsac(8) = sqrt(dX.^2+dY.^2); | |
| newsac(9) = atan2(dX,dY); % angle2 | |
| % insert new saccade into table | |
| sac(ix(1),1:9) = newsac; | |
| keep(ix(1)) = 1; | |
| keep(ix(2):ix(end)) = 0; % delete other sacc. of cluster | |
| otherwise | |
| error('\n%s(): Cluster mode not recognized. 1, 2, 3, or 4 expected.',mfilename) | |
| end | |
| end % cluster loop | |
| % remove other saccades of clusters | |
| sac = sac(keep,:); | |
| end |