Sympy:从表达式中获取函数 [英] Sympy: Get functions from expression

问题描述

要从 sympy 表达式中获取所有变量，可以对表达式调用 .free_symbols.我想检索表达式中使用的所有函数.例如，从 y in

To get all variables from a sympy expression, one can call .free_symbols on the expression. I would like to retrieve all functions used in an expression. For example, from y in

from sympy import *

f = Function('f')
g = Function('g')

x = Symbol('x')

y = f(x) + 2*g(x)

我想要f 和g.

有什么提示吗?

推荐答案

对于所有函数，使用 atoms(Function).

For all functions, use atoms(Function).

In [40]: (f(x) + sin(x)).atoms(Function)
Out[40]: set([f(x), sin(x)])

对于未定义的函数，使用atoms(AppliedUndef).

For only undefined functions, use atoms(AppliedUndef).

In [41]: from sympy.core.function import AppliedUndef

In [42]: (f(x) + sin(x)).atoms(AppliedUndef)
Out[42]: set([f(x)])

这篇关于Sympy:从表达式中获取函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！