Class FeatureTreeEdge
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FeatureTreeEdge
FIXME: out of date documentation
A modification of TreeEdge
to handle
nonterminals with features (known as Categories
.
In addition to the span, left-hand side, right-hand side, and dot
position (described at TreeEdge
), a
FeatureTreeEdge
includes vars, a set of FeatureBindings saying which FeatureVariables are set to which values.
These values are applied when examining the lhs
or
rhs
of a FeatureTreeEdge
.
For more information about edges, see the EdgeI
interface.
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VariableBindings
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Category
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lhs(self)
Returns:
the value of the left-hand side with variables set. |
source code
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Category
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Category
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rhs(self)
Returns:
the value of the right-hand side with variables set. |
source code
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Category
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__init__(self,
span,
lhs,
rhs,
dot=0,
vars=None)
(Constructor)
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Construct a new FeatureTreeEdge .
- Parameters:
span ((int, int) ) - A tuple (s,e) , where subtokens[s:e] is
the portion of the sentence that is consistent with the new
edge's structure.
lhs (Category ) - The new edge's left-hand side, specifying the hypothesized tree's
node value.
rhs (list of (Category and
string )) - The new edge's right-hand side, specifying the hypothesized
tree's children.
dot (int ) - The position of the new edge's dot. This position specifies what
prefix of the production's right hand side is consistent with the
text. In particular, if sentence is the list of
subtokens in the sentence, then
subtokens[span[0]:span[1]] can be spanned by the
children specified by rhs[:dot] .
vars (FeatureBindings) - The bindings specifying what values certain variables in this
edge must have.
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from_production(production,
index,
bindings=None)
Static Method
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- Returns: FeatureTreeEdge
- A new
FeatureTreeEdge formed from the given
production. The new edge's left-hand side and right-hand side
will be taken from production ; its span will be
(index, index) ; its dot position will be
0 , and it may have specified variables set.
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- Returns:
VariableBindings
- the
VariableBindings mapping FeatureVariables to values.
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- Returns:
Category
- the value of the left-hand side with variables set.
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- Returns:
Category
- the value of the left-hand side with no variables set.
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- Returns:
Category
- the value of the right-hand side with variables set.
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- Returns:
Category
- the value of the right-hand side with no variables set.
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