def vech(self, diagonal=True, check_symmetry=True):
        from sympy.matrices import zeros

        c = self.cols
        if c != self.rows:
            raise ShapeError("Matrix must be square")
        if check_symmetry:
            self.simplify()
            if self != self.transpose():
                raise ValueError("Matrix appears to be asymmetric; consider check_symmetry=False")
        count = 0
        if diagonal:
            v = zeros(c*(c + 1) // 2, 1)
            for j in range(c):
                for i in range(j, c):
                    v[count] = self[i, j]
                    count += 1
        else:
            v = zeros(c*(c - 1) // 2, 1)
            for j in range(c):
                for i in range(j + 1, c):
                    v[count] = self[i, j]
                    count += 1
        return v
The number of the :class:`Dataset` objects within :class:`Databook`.
dataset/ETHPy150Open sympy/sympy/sympy/matrices/matrices.py/MatrixBase.vech--crossover with--dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/tablib-0.10.0/tablib/core.py/Databook.size