Non-sequential substitution in SymPy

Question

I\'m trying to use [SymPy][1] to substitute multiple terms in an expression at the same time. I tried the [subs function][2] with a dictionary as parameter, but found out that i

Answer 1

The Keyword simultaneous will do non-clashing subs regardless of the input (dict or sequence):

>>> x.subs([(x,y),(y,z)],simultaneous=1)
y
>>> x.subs([(y,z),(x,y)],simultaneous=1)
y