#9329: Improve documentation of how to access parts of the expression tree of a
symbolic expression
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Reporter: kcrisman | Owner: burcin
Type: enhancement | Status: new
Priority: major | Milestone: sage-5.6
Component: symbolics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by kcrisman):
Resurrecting the original idea because I want this for my discrete math
class in a couple days and realize that even having a very basic example
of how to use `Converter` to make an expression tree - say one I could
plot! - would be really useful. Right now I'm stuck with Jason's idea,
which works but perhaps isn't as "Sage-ic".
{{{
sage: from sage.symbolic.random_tests import random_expr
sage: S = random_expr(20,nvars=2)
sage: S
sinh_integral(-sec(-4*abs(e))/((kronecker_delta(e, v1) -
52)*arctan(elliptic_kc(-2) - 2)))
sage: def tree(expr):
....: if expr.operator() is None:
....: return expr
....: else:
....: return [expr.operator()]+map(tree,expr.operands())
....:
sage: tree(S)
[sinh_integral, [<built-in function mul>, [<built-in function pow>,
[<built-in function add>, [kronecker_delta, [exp, 1], v1], -52], -1],
[<built-in function pow>, [arctan, [<built-in function add>, [elliptic_kc,
-2], -2]], -1], [sec, [<built-in function mul>, [abs, [exp, 1]], -4]],
-1]]
}}}
I'm realizing it might even be useful to have a (binary) tree returned
from a list of lists... but that wouldn't be here.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9329#comment:7>
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