Hello David,
in Sympy there are three substitution methods:
1. subs: it is the most generic.
2. xreplace: it only replace the exact expression you provide.
3. replace: this is the most powerful, as it allows for "pattern matching
operations".
In your case, I would do something like this:
f, g = symbols("f, g", cls=Function)
a, b, c = symbols("a:c")
expr = f(a + 2 * b + c)
expr.replace(f, g)
Davide.
Il giorno sab 19 set 2020 alle ore 21:46 David Bailey <d...@dbailey.co.uk>
ha scritto:
> Dear All,
>
> I was hoping to use SymPy patterns to perform a transformation equivalent
> to this Mathematica code:
>
> f[a + 2*b + c] /. f[x_] -> g[x]
>
> g[a + 2 b + c]
>
> I.e. I wanted to replace calls to the (undefined) function f with calls to
> the function g with the same arguments.
>
> I tried the following, with f and g set up as undefined functions:
>
> patt=Wild("p1")
>
> f(a+2*b+c).subs(f(patt),g(patt))
>
> f(a + 2*b + c)
>
> Is there a way to do this?
>
> David
>
>
>
>
>
>
>
>
>
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