Sympy no arguments in functions

Question

I have some fairly long sympy expressions and I would like not to print the arguments of all these functions. I'm searching for a general solution because I have more than thirty functions in my equations.

Example:

a=sy.Function("a")
b=sy.Function("b")
expr=a(theta,phi)*b(zeta,theta)
sy.print_latex(expr,no_args=True)

a*b

sy.print_latex(expr)
a(theta,phi)*b(zeta,theta)

Thank you for helping.

Answer 1

You need to create a custom latex printer, and override the method responsible to create latex code of applied functions. Then, you need to inform init_printing that you want to use the newly created printer. Here is how:

from sympy import *
from sympy.printing.latex import LatexPrinter
from sympy.core.function import AppliedUndef

class MyLatexPrinter(LatexPrinter):
    """ Extended Latex printer with a new option:

    applied_no_args : bool
        wheter applied undefined function should be
        rendered with their arguments. Default to False.
    """
    def __init__(self, settings=None):
        self._default_settings.update({
                "applied_no_args": False,
            }
        )
        super().__init__(settings)
        
    def _print_Function(self, expr, exp=None):
        if isinstance(expr, AppliedUndef) and self._settings["applied_no_args"]:
            if exp is None:
                return expr.func.__name__
            else:
                return r'%s^{%s}' % (expr.func.__name__, exp)
        return super()._print_Function(expr, exp)

def my_latex(expr, **settings):
    return MyLatexPrinter(settings).doprint(expr)

init_printing(latex_printer=my_latex, applied_no_args=True)
x, y, z = symbols("x:z")
f = Function("f")(x, y, z)
f