Enforce custom ordering on Sympy print

Question

SymPy does a wonderful work keeping track of all the operations I do to my symbolic expressions. But a the moment of printing the result for latex output I would li

Answer 1

If you can put the terms in the order you want then setting the order flag for the Latex printer to 'none' will print them in that order.

>>> import sympy as sp
>>> sp.init_printing()
>>> U,tp, z, d = sp.symbols('U t_\perp z d')
>>> eq=z+tp**2+U+U/(z-3*tp)+d

Here we put them in order (knowing the power of tp is 2) and rebuild as an Add with evaluate=False to keep the order unchanged

>>> p = Add(*[eq.coeff(i)*i for i in (z, U, tp**2, d)],evaluate=False)

And now we print that expression with a printer instance with order='none':

>>> from sympy.printing.latex import LatexPrinter
>>> s=LatexPrinter(dict(order='none'))
>>> s._print_Add(p)
z + U \left(1 + \frac{1}{z - 3 t_\perp}\right) + t_\perp^{2} + d