diff --git a/python/pyspark/ml/feature.py b/python/pyspark/ml/feature.py index 04b2b2ccc9e55..aa6095796183c 100644 --- a/python/pyspark/ml/feature.py +++ b/python/pyspark/ml/feature.py @@ -166,6 +166,65 @@ def getSplits(self): return self.getOrDefault(self.splits) +@inherit_doc +class DCT(JavaTransformer, HasInputCol, HasOutputCol): + """ + A feature transformer that takes the 1D discrete cosine transform of a real vector. No zero + padding is performed on the input vector. + It returns a real vector of the same length representing the DCT. The return vector is scaled + such that the transform matrix is unitary (aka scaled DCT-II). + + More information on `https://en.wikipedia.org/wiki/Discrete_cosine_transform#DCT-II Wikipedia`. + + >>> from pyspark.mllib.linalg import Vectors + >>> df = sqlContext.createDataFrame([(Vectors.dense([5.0, 8.0, 6.0]),)], ["vec"]) + >>> dct = DCT(inverse=False, inputCol="vec", outputCol="resultVec") + >>> dct.transform(df).head().resultVec + DenseVector([10.969..., -0.707..., -2.041...]) + >>> dct.setInverse(True).transform(df).head().resultVec + DenseVector([10.993..., -2.012..., -0.320...]) + """ + + # a placeholder to make it appear in the generated doc + inverse = Param(Params._dummy(), "inverse", "Set transformer to perform inverse DCT, " + + "default False.") + + @keyword_only + def __init__(self, inverse=False, inputCol=None, outputCol=None): + """ + __init__(self, inverse=False, inputCol=None, outputCol=None) + """ + super(DCT, self).__init__() + self._java_obj = self._new_java_obj("org.apache.spark.ml.feature.DCT", self.uid) + self.inverse = Param(self, "inverse", "Set transformer to perform inverse DCT, " + + "default False.") + self._setDefault(inverse=False) + kwargs = self.__init__._input_kwargs + self.setParams(**kwargs) + + @keyword_only + def setParams(self, inverse=False, inputCol=None, outputCol=None): + """ + setParams(self, inverse=False, inputCol=None, outputCol=None) + Sets params for this DCT. + """ + kwargs = self.setParams._input_kwargs + return self._set(**kwargs) + + def setInverse(self, value): + """ + Sets the value of :py:attr:`inverse`. + """ + self._paramMap[self.inverse] = value + return self + + def getInverse(self): + """ + Gets the value of inverse or its default value. + """ + return self.getOrDefault(self.inverse) + + @inherit_doc class ElementwiseProduct(JavaTransformer, HasInputCol, HasOutputCol): """