Sets the given point, connects line to previous point in group

        :param x: x value of point
        :type x: float
        :param group: group which plot point for
        :type group: float
        :param y: y value of point
        :type y: float

def setPoint(self, x, group, y):
        """Sets the given point, connects line to previous point in group

        :param x: x value of point
        :type x: float
        :param group: group which plot point for
        :type group: float
        :param y: y value of point
        :type y: float
        """
        if x == -1:
            # silence window
            self.plot([0],[y], symbol='o')
        else:
            yindex = self.groups.index(group)
            xdata, ydata = self.lines[yindex].getData()
            if ydata is None:
                xdata = [x]
                ydata = [y]
            else:
                xdata = np.append(xdata, x)
                ydata = np.append(ydata, y)
            self.lines[yindex].setData(xdata, ydata)