CODEWITHSUNDEEP
sympy
Hatshepsut
Hatshepsut

Reputation: 6662

Pretty print expression as entered

I would like to pretty print an expression to double check that it's what I want, without any manipulations or simplifications. Here's a simple example:

from sympy import *
import abc
init_session()

sigma_1, sigma_0, mu_1, mu_0,x = symbols("sigma_1 sigma_0 mu_1 mu_0 x")
diff = log(1/(sqrt(2*pi*sigma_1**2)) * exp(-(x-mu_1)**2/(2*sigma_1**2))) - log(1/(sqrt(2*pi*sigma_0**2)) * exp(-(x-mu_0)**2/(2*sigma_0**2)))
diff

enter image description here

This has manipulated the expression a bit, but I'd like to see it pretty printed just in the order I entered it, so I can check it easily against the formulas I've got written down.

Is there a way to do that?

Upvotes: 1

Views: 116

Answers (1)

asmeurer
asmeurer

Reputation: 91580

You can avoid some simplifications by using 

sympify("log(1/(sqrt(2*pi*sigma_1**2)) * exp(-(x-mu_1)**2/(2*sigma_1**2))) - log(1/(sqrt(2*pi*sigma_0**2)) * exp(-(x-mu_0)**2/(2*sigma_0**2)))", evaluate=False)

However, some simplifications can't be avoided. For example, there's no way to keep terms in the same order, and some expressions, like 1/x and x**-1 are internally represented in the same way. With that being said, there are definitely places where sympify(evaluate=False) could be improved.

Upvotes: 1

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