from sympy.core.rules import Transform
help(Transform)
On Tue, Apr 30, 2013 at 9:46 PM, Alan Bromborsky <abro...@verizon.net>wrote:
> On 04/30/2013 11:35 AM, Chris Smith wrote:
>
>> Well, I think it would be an abuse of subs to make it work with your
>> autoupdating dictionary. If I understand mul_dict, it doesn't contain any
>> entries at the start -- it becomes populated as you request ei*ej values.
>> What about using Transform:
>>
>> # a rule that all Muls get multiplied by 2
>>
>> >>> m = {} # the dictionary that keeps track of the rule
>> >>> (x+x*y+z*a).xreplace(**Transform(lambda k: m.setdefault(k, 2*k),
>> lambda w: w.is_Mul))
>> 2*a*z + 2*x*y + x
>> >>> m
>> {x*y: 2*x*y, a*z: 2*a*z}
>>
>> But that is not the right way to benefit from the dictionary since the
>> argument to setdefault is called every time. Instead (and I verify by using
>> the `ok` function that delays the number of seconds equal to its argument)
>> this is how it should be done:
>>
>> >>> def ok(i):
>> ... t=time()
>> ... while time()-t<i:pass
>> ... return i
>> ...
>> >>> (3*x+3*x*y+3*z*a).xreplace(**Transform(lambda k: m[k] if k in m else
>> m.setdefault(k, ok(k)), lambda w: w.is_Integer))
>> 3*a*z + 3*x*y + 3*x
>>
>> That only takes 3 seconds to run, not 9.
>>
>> /c
>> --
>> You received this message because you are subscribed to the Google Groups
>> "sympy" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to
>> sympy+unsubscribe@**googlegroups.com<sympy%2bunsubscr...@googlegroups.com>
>> .
>> To post to this group, send email to sympy@googlegroups.com.
>> Visit this group at
>> http://groups.google.com/**group/sympy?hl=en-US<http://groups.google.com/group/sympy?hl=en-US>
>> .
>> For more options, visit
>> https://groups.google.com/**groups/opt_out<https://groups.google.com/groups/opt_out>
>> .
>>
>>
>> Where is Transform() documented, what does it do?
>
> --
> You received this message because you are subscribed to the Google Groups
> "sympy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to
> sympy+unsubscribe@**googlegroups.com<sympy%2bunsubscr...@googlegroups.com>
> .
> To post to this group, send email to sympy@googlegroups.com.
> Visit this group at
> http://groups.google.com/**group/sympy?hl=en-US<http://groups.google.com/group/sympy?hl=en-US>
> .
> For more options, visit
> https://groups.google.com/**groups/opt_out<https://groups.google.com/groups/opt_out>
> .
>
>
>
--
You received this message because you are subscribed to the Google Groups
"sympy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sympy+unsubscr...@googlegroups.com.
To post to this group, send email to sympy@googlegroups.com.
Visit this group at http://groups.google.com/group/sympy?hl=en-US.
For more options, visit https://groups.google.com/groups/opt_out.
