Question

I’m writing a function in Sage that should work in different way for vectors and matrices.

I can not use isinstance function because type of vector or matrix depends on the type of the elements:

sage: type(matrix([[1]]))
<type 'sage.matrix.matrix_integer_dense.Matrix_integer_dense'>
sage: type(matrix([[i]]))
<type 'sage.matrix.matrix_symbolic_dense.Matrix_symbolic_dense'>

What is the best way to distinguish vectors and matrices?

Answer 1

The solution was accidentally found while trying to find definition matrix.dim in the Sage source.

from sage.matrix.matrix import is_Matrix
from sage.structure.element import is_Vector

def myfunction(x):
    if is_Vector(x):
        # do something
    elif is_Matrix(x):
        # do something else
    else:
        raise TypeError("The argument must be vector or matrix")