static List<String[]> nonegnines(List<String[]> eegdata) {
		// get rid of any -99999 values in the data by replacing with values between previous and next measured values
		
		for (int line = 2; line < eegdata.size(); line++) {
			for (int col = 3; col < eegdata.get(line).length; col++) {
				if (Double.parseDouble(eegdata.get(line)[col]) < 0) {
					
					double before = 0;
					if (line > 2)
						before = Double.parseDouble(eegdata.get(line-1)[col]);
					int numlines = 0;
					while ((line+numlines < eegdata.size()) && Double.parseDouble(eegdata.get(line+numlines)[col]) < 0) {
						numlines++;
					}
					
					double after = 0;
					if (line+numlines==eegdata.size())
						after = before;
					else {
						after = Double.parseDouble(eegdata.get(line+numlines)[col]);
						if (before == 0)
							before = after;
					}
					
					if (before < after)
						eegdata.get(line)[col] = Double.toString(before + Math.abs(after - before) / (numlines + 1));
					else
						eegdata.get(line)[col] = Double.toString(before - Math.abs(after - before) / (numlines + 1));
				}
			}
		}
		return eegdata;
	}