Opened 9 years ago

Closed 8 years ago

#10432 closed enhancement (fixed)

is_directed_acyclic is Cython (--> without NetworX) and its certificates

Reported by: ncohen Owned by: jason, ncohen, rlm
Priority: major Milestone: sage-4.6.2
Component: graph theory Keywords:
Cc: mvngu Merged in: sage-4.6.2.alpha3
Authors: Nathann Cohen Reviewers: Robert Miller
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description (last modified by ncohen)

This patch contains an Cython implementation of a method testing whether a given digraph is acyclic. If it is, the method returns a topological sort, and returns a circuit otherwise. The method is then called through current Sage methods which relied on NetworkX

def random_acyclic(n, p):
...    g = graphs.RandomGNP(n, p)
...    h = DiGraph()
...    h.add_edges([ ((u,v) if u<v else (v,u)) for u,v,_ in g.edges() ])
...    return h

Before :

sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
125 loops, best of 3: 6.54 ms per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
125 loops, best of 3: 6.79 ms per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
125 loops, best of 3: 6.72 ms per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
125 loops, best of 3: 6.96 ms per loop

After :

sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
625 loops, best of 3: 376 µs per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
625 loops, best of 3: 375 µs per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
625 loops, best of 3: 388 µs per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
625 loops, best of 3: 380 µs per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
625 loops, best of 3: 383 µs per loop
sage: g = random_acyclic(100, .2)
sage: %timeit g.is_directed_acyclic()
625 loops, best of 3: 380 µs per loop

Nathann

Requires #10435

Attachments (1)

trac_10432.patch (17.6 KB) - added by ncohen 8 years ago.

Download all attachments as: .zip

Change History (10)

comment:1 Changed 9 years ago by ncohen

  • Description modified (diff)
  • Status changed from new to needs_work

comment:2 Changed 9 years ago by mvngu

  • Cc mvngu added

comment:3 Changed 9 years ago by rlm

  • Description modified (diff)
  • Status changed from needs_work to needs_review

comment:4 Changed 9 years ago by ncohen

  • Description modified (diff)

comment:5 Changed 9 years ago by ncohen

updated to pass -testall.. This code was actually used in many places ! I hope they'll like the speedup :-)

Nathann

comment:6 Changed 9 years ago by rlm

  • Milestone changed from sage-4.6.1 to sage-4.6.2
  • Reviewers set to Robert Miller
  • Status changed from needs_review to positive_review

Looks very good.

Keep Cythonizing graph theory! :)

comment:7 Changed 8 years ago by jdemeyer

  • Status changed from positive_review to needs_work

Line 791 of sage/graphs/digraphs.py should be EXAMPLES:

comment:8 Changed 8 years ago by ncohen

  • Status changed from needs_work to positive_review

Done.

Nathann

Changed 8 years ago by ncohen

comment:9 Changed 8 years ago by jdemeyer

  • Merged in set to sage-4.6.2.alpha3
  • Resolution set to fixed
  • Status changed from positive_review to closed
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