替换部分症状表达

Suppose I have a sympy expression like this:

假设我有这样一个表达式：

x = ( 1+ r70f * C2H4 *H+ r71* O)

where r70f, C2H4, H , r71, O are sympy variables. I want it to change it to the following expression:

其中r70f，C2H4，H，r71，O是同源变量。我希望它将其更改为以下表达式：

x = ( 1+ k(r70f) * c(sC2H4) *c(sH)+ k(r71)* c(sO))

Basically replace r_SomeNumber_f to k(r_SomeNumber_f) and replace C2H4 or H or O to c(sC2H4) or c(sH) or c(sO) respectively.

基本上将r_SomeNumber_f替换为k（r_SomeNumber_f）并分别将C2H4或H或O替换为c（sC2H4）或c（sH）或c（s0）。

I am trying to use regular expressions but re.sub need str, but they are all sympy objects and that is making things complicated!!!

我试图使用正则表达式，但re.sub需要str，但它们都是sympy对象，这使事情变得复杂！

1 个解决方案

#1

I'm demonstrating two ways to do this: one with symbol trickery and the other with a wrapper function:

我正在演示两种方法：一种是带符号技巧，另一种是带有包装函数：

>>> ns={}
>>> ns["O"] = Symbol("O")
>>> x = S('1+ r70f * C2H4 *H+ r71* O', locals=ns)
>>> # Symbol trickery -- changing the name to have parens in it
>>> print(x.replace(
...     lambda x: re.match('r[0-9]+f', str(x)),
...     lambda x: Symbol('k(%s)' % str(x))))
...
C2H4*H*k(r70f) + O*r71 + 1

# function wrapper
>>> k=Function('k')
>>> print(x.replace(lambda x: re.match('r[0-9]+f', str(x)), lambda x:k(x)))
C2H4*H*k(r70f) + O*r71 + 1

NOTE: You said that you were looking for k_number_f but the case of r71 does not end with an 'f' so it isn't changed.

注意：您说您正在寻找k_number_f，但r71的情况并非以'f'结尾，因此不会更改。

I leave as an extension the conversion of the others which get wrapped with the 'c-function'.

我将其他包含'c-function'的转换作为扩展留下。

#1