% plotraw(filt-index, filt-value, x-index, y-index, data-list)
% plot raw data, assigning a column for filter, one column for x-axis and
% one for y-axis.
function plotraw(filtind, filtval, xind, yind, varargin)
    nvar = length(varargin);
    marker = '-';
    if ischar(varargin{nvar})
        marker = varargin{nvar};
        nvar = nvar - 1;
    end
    figure;
    hold on;
    for i=1:nvar
        data = sortrows(varargin{i}, xind);
        filter = data(:,filtind) == filtval;
        plot(data(filter, xind), data(filter, yind), marker);
    end
    hold off;
end