def dist(a, b):
    return sum((i-j)**2 for i, j in zip(a, b))
def inc_r(self, ind):
        r, c = self.row_col(ind)
        r += 1
        if r == self.nr:
            r = 0
        if r == (self.nr - 1) and c == (self.nc - 1):
            r = 0
        return self.indx(r, c)