#9989: easier access to operands of a symbolic expression
----------------------------------------------------+-----------------------
Reporter: burcin | Owner: burcin
Type: enhancement | Status:
positive_review
Priority: major | Milestone:
sage-4.7.1
Component: symbolics | Keywords:
Work_issues: | Upstream: N/A
Reviewer: Robert Bradshaw, Karl-Dieter Crisman | Author: Burcin
Erocal
Merged: | Dependencies:
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Old description:
> Attached patch adds an `op` attribute to symbolic expressions which gives
> easy access to its operands. We now have:
>
> {{{
> sage: x,y,z = var('x,y,z')
> sage: e = x + x*y + z^y + 3*y*z; e
> x*y + 3*y*z + z^y + x
> sage: e.op[1]
> 3*y*z
> sage: e.op[1,1]
> z
> sage: e.op[-1]
> x
> sage: e.op[1:]
> [3*y*z, z^y, x]
> }}}
>
> Using `__getitem__()` directly was not an option since it breaks
> conversion to numpy.
>
> Apply [attachment:trac_9989-operands.take3.patch]
New description:
Attached patch adds an `op` attribute to symbolic expressions which gives
easy access to its operands. We now have:
{{{
sage: x,y,z = var('x,y,z')
sage: e = x + x*y + z^y + 3*y*z; e
x*y + 3*y*z + z^y + x
sage: e.op[1]
3*y*z
sage: e.op[1,1]
z
sage: e.op[-1]
x
sage: e.op[1:]
[3*y*z, z^y, x]
}}}
Using `__getitem__()` directly was not an option since it breaks
conversion to numpy.
Apply [attachment:trac_9989-operands.take4.patch]
--
Comment(by burcin):
Good catch. Thanks, Francois.
I uploaded a new patch that just changes `module_list.py` to use
`SAGE_LOCAL` instead of `SAGE_ROOT`.
Francois, why don't you open a ticket to rename `SAGE_ROOT` in
`module_list.py` to something like `SAGE_ROOT_DO_NOT_USE` with a comment
above it to point out why `SAGE_LOCAL` is better.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9989#comment:16>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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