[英]Custom tokenizer for scikit-learn vectorizers
给出以下文件清单:
docs = [
'feature one`feature two`feature three',
'feature one`feature two`feature four',
'feature one'
]
我想使用scikit中的两个矢量化器类( CountVectorizer
或TfidfVectorizer
),其中'feature one'
, 'feature two'
, 'feature three'
和'feature four'
应该是矩阵中表示的四个功能。
我尝试了这个:
vec = CountVectorizer(token_pattern='(?u)\w+\s.\w.`')
但这仅返回以下内容:
['feature one`', 'feature two`']
如果您已将功能固定为
'feature one', 'feature two', 'feature three', and 'feature four'
然后您还可以使用vocabulary
参数。
vocab = ['feature one', 'feature two', 'feature three', 'feature four']
vec = CountVectorizer(vocabulary=vocab)
X = vec.fit_transform(docs)
vec.get_feature_names()
Out[310]:
['feature one',
'feature two',
'feature three',
'feature four']
In [295]: vec = CountVectorizer(token_pattern='(?u)\w+[\s\`]\w+')
In [296]: X = vec.fit_transform(docs)
In [297]: vec.get_feature_names()
Out[297]: ['feature four', 'feature one', 'feature three', 'feature two']
您可能还需要考虑使用ngram_range=(2,2)
,它将产生以下结果:
In [308]: vec = CountVectorizer(ngram_range=(2,2))
In [309]: X = vec.fit_transform(docs)
In [310]: vec.get_feature_names()
Out[310]:
['feature four',
'feature one',
'feature three',
'feature two',
'one feature',
'two feature']
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