So, I think I have a good test and a better understanding of the problem:
mylist = ['m', 's', 'b', 'x', 'y', 's', 'x', 'y', 's', 'EI']
sympy.var(mylist)
test = m*s**2+b*x*y*s+x**2+y**2+s+EI
args = list(test.args)
args.sort(sympy.Basic._compare_pretty)
args.reverse()
This doesn't get my list in the right order because of the number of
variables or whatever _compare_pretty does.
It seems like I need to make a dictionary or something that uses the powers
of my main variable as the keys (this could cause issues if there is more
than one arg with the same power). What is the best way to sort based on
powers of the main variable? Is this the right approach:
args[1].as_coeff_exponent('s')
(returns (y**2, 0) in this case) stepping through args in a for loop.
On Mon, Jun 1, 2009 at 5:52 PM, Ondrej Certik <ond...@certik.cz> wrote:
>
> On Mon, Jun 1, 2009 at 3:39 PM, Ryan Krauss <ryanli...@gmail.com> wrote:
> > So, when would just adding an args.reverse() breakdown:
> >
> > den3 = s**4*m1*m2+k*s**2*m2+Gc*k
> > args = list(den3.args)
> > args.sort(sympy.Basic._compare_pretty)
> > args.reverse()
> >
> > seems to produce the ordering that I want. Adding the reverse line to
> > str.py and latex.py _print_Add methods seems to work. But obviously this
> is
> > a hack.
>
> yes, it's a hack, but otherwise that's the way. Now it should just
> look for the main variable (as you suggested), that the user specifies
> optionally, and sort it with respect to it. See
> sympy/core/basic.py:Basic._compare_pretty for an example how to do
> sort it.
>
> Ondrej
>
> >
>
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