3 d%@s&ddlmZmZGdddedZdS))ABCMetaabstractmethodc@seZdZdZdZdZd!ddZddZedd Z d d Z ed"d dZ ddZ ddZ ddZddZddZddZddZddZeedd ZdS)#Featurea An abstract base class for Features. A Feature is a combination of a specific property-computing method and a list of relative positions to apply that method to. The property-computing method, M{extract_property(tokens, index)}, must be implemented by every subclass. It extracts or computes a specific property for the token at the current index. Typical extract_property() methods return features such as the token text or tag; but more involved methods may consider the entire sequence M{tokens} and for instance compute the length of the sentence the token belongs to. In addition, the subclass may have a PROPERTY_NAME, which is how it will be printed (in Rules and Templates, etc). If not given, defaults to the classname. znltk.tbl.FeatureNcCsd|_|dkr(ttdd|D|_nZy$||kr6ttt||d|_Wn4tk r}ztdj|||WYdd}~XnX|jjp|jj |_dS)al Construct a Feature which may apply at C{positions}. >>> # For instance, importing some concrete subclasses (Feature is abstract) >>> from nltk.tag.brill import Word, Pos >>> # Feature Word, applying at one of [-2, -1] >>> Word([-2,-1]) Word([-2, -1]) >>> # Positions need not be contiguous >>> Word([-2,-1, 1]) Word([-2, -1, 1]) >>> # Contiguous ranges can alternatively be specified giving the >>> # two endpoints (inclusive) >>> Pos(-3, -1) Pos([-3, -2, -1]) >>> # In two-arg form, start <= end is enforced >>> Pos(2, 1) Traceback (most recent call last): File "", line 1, in File "nltk/tbl/template.py", line 306, in __init__ raise TypeError ValueError: illegal interval specification: (start=2, end=1) :type positions: list of int :param positions: the positions at which this features should apply :raises ValueError: illegal position specifications An alternative calling convention, for contiguous positions only, is Feature(start, end): :type start: int :param start: start of range where this feature should apply :type end: int :param end: end of range (NOTE: inclusive!) where this feature should apply NcSsh|] }t|qS)int).0irr0/tmp/pip-build-v9q4h5k9/nltk/nltk/tbl/feature.py Msz#Feature.__init__..z2illegal interval specification: (start={}, end={})) positionstuplesorted TypeErrorrange ValueErrorformat __class__ PROPERTY_NAME__name__)selfr enderrr __init__#s(zFeature.__init__cCs|jS)N)r )rrrr encode_json_obj^szFeature.encode_json_objcCs |}||S)Nr)clsobjr rrr decode_json_objaszFeature.decode_json_objcCs|jjdt|jdS)N())rrlistr )rrrr __repr__fszFeature.__repr__FcsFtdd|Ds td|fdd|D}fdd|DS)a Return a list of features, one for each start point in starts and for each window length in winlen. If excludezero is True, no Features containing 0 in its positions will be generated (many tbl trainers have a special representation for the target feature at [0]) For instance, importing a concrete subclass (Feature is abstract) >>> from nltk.tag.brill import Word First argument gives the possible start positions, second the possible window lengths >>> Word.expand([-3,-2,-1], [1]) [Word([-3]), Word([-2]), Word([-1])] >>> Word.expand([-2,-1], [1]) [Word([-2]), Word([-1])] >>> Word.expand([-3,-2,-1], [1,2]) [Word([-3]), Word([-2]), Word([-1]), Word([-3, -2]), Word([-2, -1])] >>> Word.expand([-2,-1], [1]) [Word([-2]), Word([-1])] A third optional argument excludes all Features whose positions contain zero >>> Word.expand([-2,-1,0], [1,2], excludezero=False) [Word([-2]), Word([-1]), Word([0]), Word([-2, -1]), Word([-1, 0])] >>> Word.expand([-2,-1,0], [1,2], excludezero=True) [Word([-2]), Word([-1]), Word([-2, -1])] All window lengths must be positive >>> Word.expand([-2,-1], [0]) Traceback (most recent call last): File "", line 1, in File "nltk/tag/tbl/template.py", line 371, in expand :param starts: where to start looking for Feature ValueError: non-positive window length in [0] :param starts: where to start looking for Feature :type starts: list of ints :param winlens: window lengths where to look for Feature :type starts: list of ints :param excludezero: do not output any Feature with 0 in any of its positions. :type excludezero: bool :returns: list of Features :raises ValueError: for non-positive window lengths css|]}|dkVqdS)rNr)rxrrr sz!Feature.expand..znon-positive window length in c3s8|]0}tt|dD]}|||VqqdS)r N)rlen)rwr)startsrr r#scs g|]}od|ks|qS)rr)rr")r excludezerorr sz"Feature.expand..)allr)rr&Zwinlensr'xsr)rr'r&r expandis6zFeature.expandcCs |j|jkot|jt|jkS)aQ Return True if this Feature always returns True when other does More precisely, return True if this feature refers to the same property as other; and this Feature looks at all positions that other does (and possibly other positions in addition). #For instance, importing a concrete subclass (Feature is abstract) >>> from nltk.tag.brill import Word, Pos >>> Word([-3,-2,-1]).issuperset(Word([-3,-2])) True >>> Word([-3,-2,-1]).issuperset(Word([-3,-2, 0])) False #Feature subclasses must agree >>> Word([-3,-2,-1]).issuperset(Pos([-3,-2])) False :param other: feature with which to compare :type other: (subclass of) Feature :return: True if this feature is superset, otherwise False :rtype: bool )rsetr )rotherrrr issupersetszFeature.issupersetcCs$t|j|jko t|jt|j@S)a Return True if the positions of this Feature intersects with those of other More precisely, return True if this feature refers to the same property as other; and there is some overlap in the positions they look at. #For instance, importing a concrete subclass (Feature is abstract) >>> from nltk.tag.brill import Word, Pos >>> Word([-3,-2,-1]).intersects(Word([-3,-2])) True >>> Word([-3,-2,-1]).intersects(Word([-3,-2, 0])) True >>> Word([-3,-2,-1]).intersects(Word([0])) False #Feature subclasses must agree >>> Word([-3,-2,-1]).intersects(Pos([-3,-2])) False :param other: feature with which to compare :type other: (subclass of) Feature :return: True if feature classes agree and there is some overlap in the positions they look at :rtype: bool )boolrr,r )rr-rrr intersectss zFeature.intersectscCs|j|jko|j|jkS)N)rr )rr-rrr __eq__szFeature.__eq__cCs|jj|jjkp|j|jkS)N)rrr )rr-rrr __lt__szFeature.__lt__cCs ||k S)Nr)rr-rrr __ne__szFeature.__ne__cCs||kS)Nr)rr-rrr __gt__szFeature.__gt__cCs ||k S)Nr)rr-rrr __ge__szFeature.__ge__cCs||kp||kS)Nr)rr-rrr __le__szFeature.__le__cCsdS)a@ Any subclass of Feature must define static method extract_property(tokens, index) :param tokens: the sequence of tokens :type tokens: list of tokens :param index: the current index :type index: int :return: feature value :rtype: any (but usually scalar) Nr)tokensindexrrr extract_propertyszFeature.extract_property)N)F)r __module__ __qualname____doc__Zjson_tagrrr classmethodrr!r+r.r0r1r2r3r4r5r6 staticmethodrr9rrrr r s& ;  : $r) metaclassN)abcrrrrrrr  s