#5037: Bug fixes and new functionalities for Words library
---------------------------+------------------------------------------------
Reporter: slabbe | Owner: slabbe
Type: enhancement | Status: new
Priority: major | Milestone: sage-combinat
Component: combinatorics | Keywords:
Reviewer: | Author:
Merged: |
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Comment(by slabbe):
This is the example of a bad ticket having many feature to fix/add.
Fortunately, all of those were solved by #6519 merged in sage recently.
In fact, you can now glue word morphism together using the function
{{{extend_by}}} :
{{{
sage: n = WordMorphism({0:1,1:0,'a':5})
sage: m = WordMorphism('a->ab,b->ba')
sage: print n.extend_by(m)
WordMorphism: 0->1, 1->0, a->5, b->ba
sage:
sage: print m.extend_by(n)
WordMorphism: 0->1, 1->0, a->ab, b->ba
}}}
You can now restrict the domain of a morphism by using
{{{restrict_domain}}} :
{{{
sage: print n.restrict_domain([0,'a'])
WordMorphism: 0->1, a->5
}}}
You can now get the partition of the domain alphabet defined (not
uniquely) by a involution :
{{{
sage: inv = WordMorphism({0:1,1:0,2:2,3:3,4:5,5:4})
sage: inv.is_involution()
True
sage: inv.partition_of_domain_alphabet()
({0, 4}, {1, 5}, {2, 3})
}}}
The code of {{{is_involution}}} first check that self is an endomorphism
before comptuting the square of self, which gives a better error message :
{{{
sage: print n
WordMorphism: 0->1, 1->0, a->5
sage: n.is_involution()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/slabbe/.sage/temp/slabbe_laptop/8706/_home_slabbe__sage_init_sage_0.py
in <module>()
/home/slabbe/sage-4.1/local/lib/python2.6/site-
packages/sage/combinat/words/morphism.pyc in is_involution(self)
973 """
974 if not self.is_endomorphism():
--> 975 raise TypeError, "self (=%s) is not a
endomorphism"%self
976
977 return (self*self).is_identity()
TypeError: self (=WordMorphism: 0->1, 1->0, a->5) is not a endomorphism
}}}
The colored vector is not broken anymore on the empty word :
{{{
sage: empty = Word(); empty
word:
sage: empty.colored_vector()
}}}
A label can now be added to the colored vector of a word (a graphic object
useful to study equations on words) :
{{{
sage: w = Word([0..10]+[10,9..0])
sage: w.colored_vector(label='a palindrome rainbow')
}}}
Hence, I recommand that this ticket be closed.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5037#comment:2>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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