#3242: [with patch, positive review] Fix little bug in G.relabel() for G a
graph...
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Reporter: rlm | Owner: rlm
Type: defect | Status: closed
Priority: major | Milestone: sage-3.0.2
Component: graph theory | Resolution: fixed
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by chapoton:
Old description:
> Reported by Chris Godsil:
> {{{
> """
> bad4.txt
>
> Created by Chris Godsil on 2008-05-14.
>
> """
>
> I construct a graph P on 8 vertices from the Petersen graph.
>
> PROBLEMS:
> (1) The command P.relabel() raises an error as shown, but seems to work.
> (2) An attempt to get the automorphism group again raises an error, as
> shown. (3) P.is_planar() raises an exceptions.KeyError.
> (4) Attempting to get the group before relabelling raises an error too.
> (5) Ditto for P.girth()
>
> VERSION:
>
> sage: version()
> 'SAGE Version 3.0, Release Date: 2008-04-21'
>
> GRAPH CONSTRUCTION:
> P = graphs.PetersenGraph()
> P.delete_edge([0,1])
> P.add_edge([4,5])
> P.add_edge([2,6])
> P.delete_vertices([0,1])
>
> sage: P.degree()
> [3, 3, 3, 3, 3, 3, 3, 3]
>
> sage: P.vertices()
> [2, 3, 4, 5, 6, 7, 8, 9]
>
> ERRORS:
> sage: P.relabel()
> ---------------------------------------------------------------------------
> <type 'exceptions.KeyError'> Traceback (most recent call
> last)
>
> /Users/chrisgodsil/Documents/sgwork/<ipython console> in <module>()
>
> /Applications/sage/local/lib/python2.5/site-packages/sage/graphs/graph.py
> in relabel(self, perm, inplace, return_map)
> 5791 new_pos = {}
> 5792 for v in self._pos:
> -> 5793 new_pos[perm[v]] = self._pos[v]
> 5794 self._pos = new_pos
> 5795 self._boundary = [perm[v] for v in self._boundary]
>
> <type 'exceptions.KeyError'>: 0
>
> sage: P.vertices()
> [0, 1, 2, 3, 4, 5, 6, 7]
>
> sage: P.automorphism_group()
> ---------------------------------------------------------------------------
> <type 'exceptions.KeyError'> Traceback (most recent call
> last)
>
> /Users/chrisgodsil/Documents/sgwork/<ipython console> in <module>()
>
> /Applications/sage/local/lib/python2.5/site-packages/sage/graphs/graph.py
> in automorphism_group(self, partition, translation, verbosity,
> edge_labels, order, return_group, orbits)
> 6159 a,b = A
> 6160 else:
> -> 6161 a = search_tree(self, partition, dict_rep=False,
> lab=False, dig=dig, verbosity=verbosity, order=order)
> 6162 if order:
> 6163 a,c = a
>
> /Users/chrisgodsil/Documents/sgwork/graph_isom.pyx in
> sage.graphs.graph_isom.search_tree (sage/graphs/graph_isom.c:8990)()
>
> /Applications/sage/local/lib/python2.5/site-packages/sage/graphs/graph.py
> in relabel(self, perm, inplace, return_map)
> 5791 new_pos = {}
> 5792 for v in self._pos:
> -> 5793 new_pos[perm[v]] = self._pos[v]
> 5794 self._pos = new_pos
> 5795 self._boundary = [perm[v] for v in self._boundary]
>
> <type 'exceptions.KeyError'>: 8
> }}}
New description:
Reported by Chris Godsil:
{{{
"""
bad4.txt
Created by Chris Godsil on 2008-05-14.
"""
I construct a graph P on 8 vertices from the Petersen graph.
PROBLEMS:
(1) The command P.relabel() raises an error as shown, but seems to work.
(2) An attempt to get the automorphism group again raises an error, as
shown. (3) P.is_planar() raises an exceptions.KeyError.
(4) Attempting to get the group before relabelling raises an error too.
(5) Ditto for P.girth()
VERSION:
sage: version()
'SAGE Version 3.0, Release Date: 2008-04-21'
GRAPH CONSTRUCTION:
P = graphs.PetersenGraph()
P.delete_edge([0,1])
P.add_edge([4,5])
P.add_edge([2,6])
P.delete_vertices([0,1])
sage: P.degree()
[3, 3, 3, 3, 3, 3, 3, 3]
sage: P.vertices()
[2, 3, 4, 5, 6, 7, 8, 9]
ERRORS:
sage: P.relabel()
---------------------------------------------------------------------------
<type 'exceptions.KeyError'> Traceback (most recent call
last)
/Users/chrisgodsil/Documents/sgwork/<ipython console> in <module>()
/Applications/sage/local/lib/python2.5/site-packages/sage/graphs/graph.py
in relabel(self, perm, inplace, return_map)
5791 new_pos = {}
5792 for v in self._pos:
-> 5793 new_pos[perm[v]] = self._pos[v]
5794 self._pos = new_pos
5795 self._boundary = [perm[v] for v in self._boundary]
<type 'exceptions.KeyError'>: 0
sage: P.vertices()
[0, 1, 2, 3, 4, 5, 6, 7]
sage: P.automorphism_group()
---------------------------------------------------------------------------
<type 'exceptions.KeyError'> Traceback (most recent call
last)
/Users/chrisgodsil/Documents/sgwork/<ipython console> in <module>()
/Applications/sage/local/lib/python2.5/site-packages/sage/graphs/graph.py
in automorphism_group(self, partition, translation, verbosity,
edge_labels, order, return_group, orbits)
6159 a,b = A
6160 else:
-> 6161 a = search_tree(self, partition, dict_rep=False,
lab=False, dig=dig, verbosity=verbosity, order=order)
6162 if order:
6163 a,c = a
/Users/chrisgodsil/Documents/sgwork/graph_isom.pyx in
sage.graphs.graph_isom.search_tree (sage/graphs/graph_isom.c:8990)()
/Applications/sage/local/lib/python2.5/site-packages/sage/graphs/graph.py
in relabel(self, perm, inplace, return_map)
5791 new_pos = {}
5792 for v in self._pos:
-> 5793 new_pos[perm[v]] = self._pos[v]
5794 self._pos = new_pos
5795 self._boundary = [perm[v] for v in self._boundary]
<type 'exceptions.KeyError'>: 8
}}}
--
--
Ticket URL: <http://trac.sagemath.org/ticket/3242#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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