On Thu, 21 Mar 2019 at 18:42, Ai Bo <boaisp...@gmail.com> wrote:
> I found it. Thank you.
> I also tried the command listed above.
> I am confused. Where is this "I]~~~~~~w"?
> Is it a file? How did Graph load this?
>
> In my program, my code looks like this:
> i=12
> for G in graphs.nauty_geng(str(i) + " -C"):
> q = True
> for j in range (0,i):
> S = Sandpile(G,j)
> if S.identity() != S.max_stable():
> q = False
> break
>
>
>
> If I use geng to generate graphs, how should I load them in my for loop so
> I can check with Sandpile?
>
I think the bottleneck in you computation is not geng, but Sandpile: you
spend much more time computing Sandpile compared with asking geng for the
next graph.
> On Thursday, March 21, 2019 at 8:46:56 AM UTC-7, Dima Pasechnik wrote:
>>
>> On Thu, Mar 21, 2019 at 3:03 PM Ai Bo <boai...@gmail.com> wrote:
>>
>> > is this "nauty26r7/geng" a program available?
>>
>> geng is installed in local/bin/ sub-directory of your Sage
>> installation, as a part of Sage's standard package nauty.
>>
>> > Also, as Python is slow, any part of the nautygen can be written in
>> other language, such as C/C++?
>>
>> it is written in C, so it's quite fast in this sense.
>>
>> >
>> > Thanks,
>> > Laura
>> >
>> > On Wednesday, March 20, 2019 at 11:48:38 PM UTC-7, Jori Mäntysalo (TAU)
>> wrote:
>> >>
>> >> On Thu, 21 Mar 2019, Ai Bo wrote:
>> >>
>> >> > Is there a way to "random access"? For example, access the nth
>> element
>> >> > in the "generator", instead of one by one?
>> >>
>> >> Kind of. As a most time is propably spent by creating Python data
>> >> structures for SageMath, you can use nautygen directly to generate
>> huge
>> >> number of graphs.
>> >>
>> >> As an example, it takes below 5 seconds to generate all biconnected
>> graphs
>> >> on 10 vertices, and I took third last one:
>> >>
>> >> $ nauty26r7/geng 10 -C | tail -3 | head -1
>> >> >A /home/jm58660/lat-koe/nauty26r7/geng -Cd2D9 n=10 e=10-45
>> >> >Z 9743542 graphs generated in 4.59 sec
>> >> I]~~~~~~w
>> >>
>> >> and now
>> >>
>> >> sage: g = Graph('I]~~~~~~w', format='graph6')
>> >> sage: g.is_biconnected()
>> >> True
>> >>
>> >>
>> >> --
>> >> Jori Mäntysalo
>> >>
>> >> Tampereen yliopisto - Ihminen ratkaisee
>> >
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