在sympy中使用符号形式和向量形式的变量？

Question

If R = [0, 0, 1] , there are some cases when I would like to use Symbol('R') and others when Matrix([0, 0, 1]) is more useful in equations. How do I pick and choose when to use each form without defining too many variables? (eg R = Symbol('R') and R_vec = Matrix([0, 0, 1]) is bad)

Answer 1

One way of approaching this problem is to define R as a symbol, which you can substitute, via subs() , when needed, eg:

import sympy as sym


R = sym.Symbol('R')
R.subs({'R': sym.Matrix([1, 0, 0])})                                                                                                                    
# Matrix([
# [1],
# [0],
# [0]])

---

As per @OscarBenjamin comment, you may possibly prefer a MatrixSymbol() over a regular Symbol() as it will play more nicely with matrix operations.

Answer 2

Thank you for the suggestions. For my particular project I think it's suitable to store both sides of the equation in a tuple (LHS, RHS) from the get-go and just use each side R[i] when needed. I understand I asked you for how to deal with this in sympy specifically, so thank you for your sympy specific answers

R = (Symbol('R'), Matrix([0, 0, 1]))