#19275: handle empty matroid in partition
-------------------------------------+-------------------------------------
Reporter: chaoxu | Owner:
Type: defect | Status: needs_review
Priority: trivial | Milestone: sage-6.9
Component: matroid theory | Resolution:
Keywords: | Merged in:
Authors: Chao Xu | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/chaoxu/partitiondividebyzero | 79f01f9100ea8e9d8275ba72e712bcb478343102
Dependencies: | Stopgaps:
-------------------------------------+-------------------------------------
Comment (by tscrim):
Yea, that is better.
In a related issue; I tried the following ways to naturally create an
empty matroid:
{{{
sage: Matroid()
...
UnboundLocalError: local variable 'M' referenced before assignment
sage: Matroid([])
...
ValueError: min() arg is an empty sequence
sage: Matroid(groundset=[], bases=[])
...
ValueError: min() arg is an empty sequence
}}}
You might want to consider changing things so that these could give you an
empty matroid. Also, is this correct?
{{{
sage: M = Matroid(Graph()); M
Regular matroid of rank 0 on 0 elements with 1 bases
sage: list(M.bases())
[frozenset()]
}}}
(All of that is another ticket.)
However, this worked:
{{{
sage: Matroid(matrix([]))
Linear matroid of rank 0 on 0 elements represented over the Rational Field
}}}
Could you use that for the test since it uses the top-level interface?
--
Ticket URL: <http://trac.sagemath.org/ticket/19275#comment:7>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
