How do i convert sympy matrix output into numpy array

Question

Attached below is my code

import sympy as sym

k = [3,10,0.65,0.3]
x = [999, 1, 0] 
SU, IN, IM= x[0], x[1], x[2]

def equation():   
    dsdt = '(IM/k0) - ((IN/(IN+SU))*k1*k2*SU)'
    dindt = '((IN/(IN+SU))*k1*k2*SU) - (IN/k3)'
    dimdt = '(IN/k3) - (IM/k0)'
    return [dsdt, dindt, dimdt]

def Jacobian(v_str, f_list):
    vars = sym.symbols(v_str)
    f = sym.sympify(f_list)
    J = sym.zeros(len(f),len(vars))
    for i, fi in enumerate(f):
        for j, s in enumerate(vars):
            J[i,j] = sym.diff(fi, s)
    return J

Jacobian('k0 k1 k2 k3', equation())

I need the return value to be in numpy.array for further processing... now im just hard coding it. Using jupyter notebook, python version 3.7.6

Sample output:

sample output

What are the matrix elements in the returned matrix `J`? Numbers only? — amzon-ex, May 30 '20 at 15:11
Is it what you need https://stackoverflow.com/questions/32930284/how-to-substitute-multiple-symbols-in-an-expression-in-sympy? — V. Ayrat, May 30 '20 at 15:33
@V.Ayrat AttributeError: MutableDenseMatrix has no attribute sub. — zhikai, May 30 '20 at 16:23

score 0 · Answer 1 · answered May 30 '20 at 17:28

0

If you want a numpy array then the following will work: flatten the matrix and pass it to array:

from numpy import array
from sympy import flatten, Matrix
print(array(flatten(Matrix(equation()).jacobian(var('k0 k1 k2 k3')))))

answered May 30 '20 at 17:28

smichr

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How do i convert sympy matrix output into numpy array

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