subs function giving me error message

[Adam S]

Hi,
I am getting confused on Python 3 error message using subs:

from sympy import *
x, y = symbols('x y')
fun = cos(x) + 1
fun.subs(x,y)

--> cos(y) + 1

which is okay. It does at it should.

from sympy import *
x, y = symbols('x y')
fun2=1
fun2.subs(x,y)

--> Attribute error: 'int' object has not attribute 'subs'

What is the failure here?  How to fix this?  I used sympy online and it works, but on desktop it does not.  Why?

I used recently anaconda to download python 3 and other libraries etc.

[Aaron Meurer]

If your expression is a pure Python integer or float, you have to
convert it to a SymPy type first to use SymPy methods on it. So

fun2 = Integer(1)

will work. In general, you can use sympify(), or the shorter S() to
convert things to SymPy types.

It works in the SymPy Live online shell because that shell wraps
integers with Integer() automatically.

Aaron Meurer

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