python - How to use numpy arrays with fractions?

Question

I'm trying to implement the simplex method in Python so I need to use the Gaussian elimination on arrays. Very often fractions come up and for more clarity and precision I would like to keep the fractional form instead of using floats. I know the 'fractions' module but I'm struggling to use it. I wrote my code using this module but the arrays are always returned with floats. Isn't it possible to print an array with fractions inside ? On this basic example :

>>> A
array([[-1.,  1.],
       [-2., -1.]])
>>> A[0][0] = Fraction(2, 3)
>>> A
array([[ 0.66666667,  1. ],
       [-2.        , -1. ]])

I would like to have

array([[2/3,    1. ],
       [-2.,   -1. ]])

It seems numpy always switches to floats

Answer 1

You can also convert the entire array to an object array of Fraction objects, by abusing the element-wise conversion of numpy arrays under arithmetic operations. (Note: this requires the original array to be an integer array, since arithmetic between floats and Fractions produce floats.)

>>> A = np.array([[-1,  1],[-2, -1]])
array([[-1,  1],
       [-2, -1]])
>>>
>>> A.dtype
dtype('int64')
>>>
>>> A = A + Fraction()
>>> A
array([[Fraction(-1, 1), Fraction(1, 1)],
       [Fraction(-2, 1), Fraction(-1, 1)]], dtype=object)

With the array in this format, any further arithmetic performed will be over elements of type Fraction.