androidMotionLogger/MATLAB/generateTrainingDataFromCSV.m

function [data, labels] = generateTrainingDataFromCSV(file, framesize, frameoffset, maxFrameShift)
% generateTrainingDataFromCSV(file, framesize, frameoffset, maxFrameShift)
% generating frames with fixed number of samples, parametrized by framesize
% and frameoffset. frameoffset determines the number of sample to include
% before the actual touch event
% maxFrameShift determines the jitter in both directions when determining
% the origin of the frame based on the postion of the touch event

  X_COORD = 10;
  Y_COORD = 11;
  
  % read the csv and start in the second row, first column

  sizeData = size(file);
  fprintf("read %d sensor samples\n", sizeData(1));
  
  % find the action down events
  indices = find(file(:,9) == 1);
  data = []; % zeros(framesize, 6, size(indices,1) * (2 * maxFrameShift + 1));
  labels = []; % zeros(2, size(indices,1) * (2 * maxFrameShift + 1));
  % create the frames and labels
  for i = -maxFrameShift:maxFrameShift
      data = cat(3, data, getSamplesFromData(file, indices + i, framesize, frameoffset));
      labels = cat(2, labels, file(indices, X_COORD:Y_COORD)');
  end
  fprintf("created %d frames out of %d touch events\n", size(data, 3), length(indices));
end

function samples = getSamplesFromData(file, indices, framesize, frameoffset)
  GYRO_X = 2;
  GYRO_Y = 3;
  GYRO_Z = 4;
  ACC_X = 6;
  ACC_Y = 7;  
  ACC_Z = 8;
  
  samples = zeros(framesize, 6, size(indices,1));
  dataidx = 1;
  for i = indices'
      % creates a (framesize x 6 x batchsize) tensor 
      if (i-frameoffset+framesize < size(file, 1) && i - frameoffset > 0) 
          samples(:, :, dataidx) = cat(2, file(i-frameoffset:i-frameoffset+framesize-1,GYRO_X:GYRO_Z), file(i-frameoffset:i-frameoffset+framesize-1,ACC_X:ACC_Z));
          dataidx = dataidx + 1;
      end
  end
end