#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
from pyspark.rdd import ignore_unicode_prefix
from pyspark.ml.param.shared import HasInputCol, HasInputCols, HasOutputCol, HasNumFeatures
from pyspark.ml.util import keyword_only
from pyspark.ml.wrapper import JavaTransformer
from pyspark.mllib.common import inherit_doc
__all__ = ['Tokenizer', 'HashingTF', 'VectorAssembler']
@inherit_doc
@ignore_unicode_prefix
class Tokenizer(JavaTransformer, HasInputCol, HasOutputCol):
"""
A tokenizer that converts the input string to lowercase and then
splits it by white spaces.
>>> from pyspark.sql import Row
>>> df = sc.parallelize([Row(text="a b c")]).toDF()
>>> tokenizer = Tokenizer(inputCol="text", outputCol="words")
>>> tokenizer.transform(df).head()
Row(text=u'a b c', words=[u'a', u'b', u'c'])
>>> # Change a parameter.
>>> tokenizer.setParams(outputCol="tokens").transform(df).head()
Row(text=u'a b c', tokens=[u'a', u'b', u'c'])
>>> # Temporarily modify a parameter.
>>> tokenizer.transform(df, {tokenizer.outputCol: "words"}).head()
Row(text=u'a b c', words=[u'a', u'b', u'c'])
>>> tokenizer.transform(df).head()
Row(text=u'a b c', tokens=[u'a', u'b', u'c'])
>>> # Must use keyword arguments to specify params.
>>> tokenizer.setParams("text")
Traceback (most recent call last):
...
TypeError: Method setParams forces keyword arguments.
"""
_java_class = "org.apache.spark.ml.feature.Tokenizer"
@keyword_only
def __init__(self, inputCol=None, outputCol=None):
"""
__init__(self, inputCol=None, outputCol=None)
"""
super(Tokenizer, self).__init__()
kwargs = self.__init__._input_kwargs
self.setParams(**kwargs)
@keyword_only
def setParams(self, inputCol=None, outputCol=None):
"""
setParams(self, inputCol="input", outputCol="output")
Sets params for this Tokenizer.
"""
kwargs = self.setParams._input_kwargs
return self._set(**kwargs)
@inherit_doc
class HashingTF(JavaTransformer, HasInputCol, HasOutputCol, HasNumFeatures):
"""
Maps a sequence of terms to their term frequencies using the
hashing trick.
>>> from pyspark.sql import Row
>>> df = sc.parallelize([Row(words=["a", "b", "c"])]).toDF()
>>> hashingTF = HashingTF(numFeatures=10, inputCol="words", outputCol="features")
>>> hashingTF.transform(df).head().features
SparseVector(10, {7: 1.0, 8: 1.0, 9: 1.0})
>>> hashingTF.setParams(outputCol="freqs").transform(df).head().freqs
SparseVector(10, {7: 1.0, 8: 1.0, 9: 1.0})
>>> params = {hashingTF.numFeatures: 5, hashingTF.outputCol: "vector"}
>>> hashingTF.transform(df, params).head().vector
SparseVector(5, {2: 1.0, 3: 1.0, 4: 1.0})
"""
_java_class = "org.apache.spark.ml.feature.HashingTF"
@keyword_only
def __init__(self, numFeatures=1 << 18, inputCol=None, outputCol=None):
"""
__init__(self, numFeatures=1 << 18, inputCol=None, outputCol=None)
"""
super(HashingTF, self).__init__()
self._setDefault(numFeatures=1 << 18)
kwargs = self.__init__._input_kwargs
self.setParams(**kwargs)
@keyword_only
def setParams(self, numFeatures=1 << 18, inputCol=None, outputCol=None):
"""
setParams(self, numFeatures=1 << 18, inputCol=None, outputCol=None)
Sets params for this HashingTF.
"""
kwargs = self.setParams._input_kwargs
return self._set(**kwargs)
@inherit_doc
class VectorAssembler(JavaTransformer, HasInputCols, HasOutputCol):
"""
A feature transformer that merges multiple columns into a vector column.
>>> from pyspark.sql import Row
>>> df = sc.parallelize([Row(a=1, b=0, c=3)]).toDF()
>>> vecAssembler = VectorAssembler(inputCols=["a", "b", "c"], outputCol="features")
>>> vecAssembler.transform(df).head().features
SparseVector(3, {0: 1.0, 2: 3.0})
>>> vecAssembler.setParams(outputCol="freqs").transform(df).head().freqs
SparseVector(3, {0: 1.0, 2: 3.0})
>>> params = {vecAssembler.inputCols: ["b", "a"], vecAssembler.outputCol: "vector"}
>>> vecAssembler.transform(df, params).head().vector
SparseVector(2, {1: 1.0})
"""
_java_class = "org.apache.spark.ml.feature.VectorAssembler"
@keyword_only
def __init__(self, inputCols=None, outputCol=None):
"""
__init__(self, inputCols=None, outputCol=None)
"""
super(VectorAssembler, self).__init__()
self._setDefault()
kwargs = self.__init__._input_kwargs
self.setParams(**kwargs)
@keyword_only
def setParams(self, inputCols=None, outputCol=None):
"""
setParams(self, inputCols=None, outputCol=None)
Sets params for this VectorAssembler.
"""
kwargs = self.setParams._input_kwargs
return self._set(**kwargs)
if __name__ == "__main__":
import doctest
from pyspark.context import SparkContext
from pyspark.sql import SQLContext
globs = globals().copy()
# The small batch size here ensures that we see multiple batches,
# even in these small test examples:
sc = SparkContext("local[2]", "ml.feature tests")
sqlContext = SQLContext(sc)
globs['sc'] = sc
globs['sqlContext'] = sqlContext
(failure_count, test_count) = doctest.testmod(
globs=globs, optionflags=doctest.ELLIPSIS)
sc.stop()
if failure_count:
exit(-1)
