CODEWITHSUNDEEP
tuplesinstancesympytrigonometry
user20693776
user20693776

Reputation:

sympy: check if expression is a trigonometric function

I have a dict that contains tuples as keys with a sympy expression and the number of arguments in each tuple and as value a customized translation. I want to check if the sympy expression is a trigonometric function i.e a function of those: https://omz-software.com/pythonista/sympy/modules/mpmath/functions/trigonometric.html

Do you guys know a nice command to check this? I could just think of a list in which I name [sin, cos, tan] etc and then check if key is contained in it. But I'd be really happy if there was a nicer solution.

Can one generally classify sympy expression and check to which class of expression they belong?

       default_semantic_latex_table = {
            (sympy.functions.elementary.trigonometric.sin, 1): FormatTemplate(r"\sin@{$0}"), (sympy.functions.special.polynomials.jacobi, 4): FormatTemplate(r"\JacobipolyP{{$0}{$1}{$2}@{$3}}"),
            (sympy.functions.elementary.trigonometric.cos, 2): FormatTemplate(r"\cos@{$0,$2}")
        }

        for k, v in default_semantic_latex_table:
            # check if key is instance of a sympy trigonometric function
            # if so and the number of args is not equal to one, throw a warning

If the if condition evaluates to True, I want to check the second element of the tuple/the number of args. How would I do that? I expected k to be a tuple like (sympy.functions.special.polynomials.jacobi, 4) yet if I test it k turns out to be just sympy.functions.special.polynomials.jacobi. How can I get the second tuple element? I'd be really glad if someone could help!

Upvotes: 0

Views: 125

Answers (1)

Davide_sd
Davide_sd

Reputation: 13150

You can import the TrigonometricFunction base class from sympy and use the issubclass method to perform the tests.

Note that you have to use dictionary_name.items() in order to loop over the keys and values of a dictionary:

from sympy import *
import sympy
from sympy.functions.elementary.trigonometric import TrigonometricFunction
import warnings

default_semantic_latex_table = {
    (sympy.functions.elementary.trigonometric.sin, 1): "a",
    (sympy.functions.elementary.trigonometric.cos, 2): "b"
}

for k, v in default_semantic_latex_table.items():
    t, n = k
    if issubclass(t, TrigonometricFunction) and (n != 1):
        warnings.warn("Your warning: function=%s with n=%s" % (t, n))

Upvotes: 1

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