#15206: Poset show should accept non-hashable or non-injective element labels
------------------------------------------------+------------------------
Reporter: darij | Owner:
Type: task | Status: new
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: combinat, show, plot, posets | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by jmantysalo:
Old description:
> {{{
> sage: P = Poset({1: [2,3]})
> sage: labs = {i: P.rank(i) for i in range(1, 4)}
> sage: labs
> {1: 0, 2: 1, 3: 1}
> sage: P.show(element_labels=labs)
> ---------------------------------------------------------------------------
> NotImplementedError Traceback (most recent call
> last)
> <ipython-input-38-dfd00191eb55> in <module>()
> ----> 1 P.show(element_labels=labs)
>
> /home/darij/sage-5.12.beta5/local/lib/python2.7/site-
> packages/sage/combinat/posets/posets.pyc in show(self, label_elements,
> element_labels, vertex_size, vertex_colors, layout, **kwds)
> 1440 """
> 1441 self.plot(label_elements=label_elements,
> element_labels=element_labels,
> -> 1442 vertex_size=vertex_size, vertex_colors=vertex_colors,
> layout=layout).show(**kwds)
> 1443
> 1444 @combinatorial_map(name="to graph")
>
> /home/darij/sage-5.12.beta5/local/lib/python2.7/site-
> packages/sage/combinat/posets/posets.pyc in plot(self, label_elements,
> element_labels, vertex_size, vertex_colors, layout, **kwds)
> 1402 relabelling = dict((self(element), label)
> 1403 for (element, label) in
> element_labels.items())
> -> 1404 graph = graph.relabel(relabelling, inplace = False)
> 1405 if rank_function: # use the rank function to set the
> heights
> 1406 for i in self:
>
> /home/darij/sage-5.12.beta5/local/lib/python2.7/site-
> packages/sage/graphs/generic_graph.pyc in relabel(self, perm, inplace,
> return_map, check_input, complete_partial_function)
> 16208 return_map= return_map,
> 16209 check_input = check_input,
> > 16210 complete_partial_function =
> complete_partial_function)
> 16211
> 16212 if return_map:
>
> /home/darij/sage-5.12.beta5/local/lib/python2.7/site-
> packages/sage/graphs/generic_graph.pyc in relabel(self, perm, inplace,
> return_map, check_input, complete_partial_function)
> 16263 if check_input:
> 16264 if len(set(perm.values())) < len(perm):
> > 16265 raise NotImplementedError("Non injective
> relabeling")
> 16266
> 16267 for v in perm.iterkeys():
>
> NotImplementedError: Non injective relabeling
> }}}
>
> I understand that this, along with the lack of support for non-hashable
> labels, is owed to the implementation, but IMHO this means that the
> implementation (via relabelling the poset before plotting it, rather than
> as one would expect via doing everything as if the labels weren't there
> and then introducing them at the very end) is bad. (Incidentally, I'm not
> even sure that the shape of the image doesn't depend on the labels -- in
> the examples I've checked it seems to not depend on them, but I don't
> trust the code very much.)
>
> I am not the type of mathematician who gets any enlightenment out of
> pictures, but even I do need to use {{{show()}}} when I'm making a
> presentation. Issues like this harm the presentability of Sage code.
New description:
{{{
sage: P = Poset({1: [2,3]})
sage: labs = {i: P.rank(i) for i in range(1, 4)}
sage: labs
{1: 0, 2: 1, 3: 1}
sage: P.show(element_labels=labs)
---------------------------------------------------------------------------
NotImplementedError Traceback (most recent call
last)
<ipython-input-38-dfd00191eb55> in <module>()
----> 1 P.show(element_labels=labs)
/home/darij/sage-5.12.beta5/local/lib/python2.7/site-
packages/sage/combinat/posets/posets.pyc in show(self, label_elements,
element_labels, vertex_size, vertex_colors, layout, **kwds)
1440 """
1441 self.plot(label_elements=label_elements,
element_labels=element_labels,
-> 1442 vertex_size=vertex_size, vertex_colors=vertex_colors,
layout=layout).show(**kwds)
1443
1444 @combinatorial_map(name="to graph")
/home/darij/sage-5.12.beta5/local/lib/python2.7/site-
packages/sage/combinat/posets/posets.pyc in plot(self, label_elements,
element_labels, vertex_size, vertex_colors, layout, **kwds)
1402 relabelling = dict((self(element), label)
1403 for (element, label) in
element_labels.items())
-> 1404 graph = graph.relabel(relabelling, inplace = False)
1405 if rank_function: # use the rank function to set the
heights
1406 for i in self:
/home/darij/sage-5.12.beta5/local/lib/python2.7/site-
packages/sage/graphs/generic_graph.pyc in relabel(self, perm, inplace,
return_map, check_input, complete_partial_function)
16208 return_map= return_map,
16209 check_input = check_input,
> 16210 complete_partial_function =
complete_partial_function)
16211
16212 if return_map:
/home/darij/sage-5.12.beta5/local/lib/python2.7/site-
packages/sage/graphs/generic_graph.pyc in relabel(self, perm, inplace,
return_map, check_input, complete_partial_function)
16263 if check_input:
16264 if len(set(perm.values())) < len(perm):
> 16265 raise NotImplementedError("Non injective
relabeling")
16266
16267 for v in perm.iterkeys():
NotImplementedError: Non injective relabeling
}}}
I understand that this, along with the lack of support for non-hashable
labels, is owed to the implementation, but IMHO this means that the
implementation (via relabelling the poset before plotting it, rather than
as one would expect via doing everything as if the labels weren't there
and then introducing them at the very end) is bad. (Incidentally, I'm not
even sure that the shape of the image doesn't depend on the labels -- in
the examples I've checked it seems to not depend on them, but I don't
trust the code very much.)
I am not the type of mathematician who gets any enlightenment out of
pictures, but even I do need to use {{{show()}}} when I'm making a
presentation. Issues like this harm the presentability of Sage code.
Fixing this would also help with problem when combining `vertex_colors`
and `element_labels`. See for example
{{{
Poset({1:[]}).plot(vertex_colors={'red':[1]}, element_labels={1: 2})
}}}
--
--
Ticket URL: <http://trac.sagemath.org/ticket/15206#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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