Evaluate Sympy boolean expression in python

Question

I am using Python and Sympy.

I have the following:

x,y,z = Symbols('x,y,z')
doc = {x : False, y : True, z: True}
rule = Or(x, And(y,z))

I am looking for a function in Sympy that will return True on rule.eval(doc) ?

Edit: Currently I am using rule.subs and rule.xreplace both are performing slowly with about 0.0003 seconds per call. This makes it impractical.

Answer 1

A way to get better performance with minimal coding is to use lambdify :

X = tuple(doc.iterkeys())
f = lambdify(X, rule)

After this IPython gave me:

V = tuple(doc.itervalues())
%timeit f(*V)
The slowest run took 7.56 times longer than the fastest. This could mean that an intermediate result is being cached.
1000000 loops, best of 3: 209 ns per loop

I am not sure how much the warning may impact the conclusion, but there is a clear improvement. On the same computer I had with the original code:

%timeit rule.xreplace(doc)
10000 loops, best of 3: 126 µs per loop

And subs was even slower.

Answer 2

Rather than using subs can you use direct evaluation?

>>> F = Lambda((x, y, z), Or(x, And(y, z)))
>>> F(0, 1, 1)
True

If not, could you create a toy class that will allow subs via the lambda form? This is not a class but it gives the idea:

>>> def sub(f, d):
...     F = Lambda(d.keys(), f)
...     return F(*[d[k] for k in d.keys()])
>>> sub(Or(x,And(y,z)),{x:0,y:1,z:1})

The class would create the Lambda form and have a subs method which would return the evaluated Lambda form.