#12181: random_DAG does not terminate on it's default inputs
------------------------------------------+---------------------------------
Reporter: mderickx | Owner: tbd
Type: defect | Status: needs_work
Priority: major | Milestone: sage-5.3
Component: graph theory | Resolution:
Keywords: random digraph | Work issues:
Report Upstream: N/A | Reviewers: David Coudert
Authors: dsm, Frédéric Chapoton | Merged in:
Dependencies: | Stopgaps:
------------------------------------------+---------------------------------
Changes (by dcoudert):
* status: needs_review => needs_work
* reviewer: => David Coudert
Comment:
Hello,
The patch needs further improvements.
1) The test on p should be improved since I can give p=2 without error.
For instance,
{{{
if p < 0 or p > 1:
raise ValueError('The parameter p must be in [0..1].')
}}}
2) A test is needed for parameter weight_max:
{{{
sage: random_DAG(5, .5, -1)
---------------------------------------------------------------------------
ValueError Traceback (most recent call
last)
...
...
ValueError: empty range for randrange() (1,0, -1)
}}}
and
{{{
sage: random_DAG(5, .5, .5)
---------------------------------------------------------------------------
ValueError Traceback (most recent call
last)
...
...
ValueError: non-integer stop for randrange()
}}}
3) It should be clearly indicated in the documentation that the function
returns a dictionary storing the edges of the DAG.
4) The resulting number of vertices is not n but n+1:
{{{
sage: d = DiGraph(random_DAG(5, .5))
sage: d
Digraph on 6 vertices
}}}
5) I don't understand why this digraph generator is not part of
```sage.graphs.digraph_generators.py```. The function could have an
optional parameter to return a dictionary instead of a digraph if
relevant.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12181#comment:15>
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