[SPARK-4494][mllib] IDFModel.transform() add support for single vector

I improved `IDFModel.transform` to allow using a single vector.

[[SPARK-4494] IDFModel.transform() add support for single vector - ASF JIRA](https://issues.apache.org/jira/browse/SPARK-4494)

Author: Yuu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #3603 from yu-iskw/idf and squashes the following commits:

256ff3d [Yuu ISHIKAWA] Fix typo
a3bf566 [Yuu ISHIKAWA] - Fix typo - Optimize import order - Aggregate the assertion tests - Modify `IDFModel.transform` API for pyspark
d25e49b [Yuu ISHIKAWA] Add the implementation of `IDFModel.transform` for a term frequency vector

1 files changed, 15 insertions, 7 deletions

diff --git a/python/pyspark/mllib/feature.py b/python/pyspark/mllib/feature.py
index 8cb992df2d..741c630cbd 100644
--- a/python/pyspark/mllib/feature.py
+++ b/python/pyspark/mllib/feature.py
@@ -28,7 +28,7 @@ from py4j.protocol import Py4JJavaError
 
 from pyspark import RDD, SparkContext
 from pyspark.mllib.common import callMLlibFunc, JavaModelWrapper
-from pyspark.mllib.linalg import Vectors, _convert_to_vector
+from pyspark.mllib.linalg import Vectors, Vector, _convert_to_vector
 
 __all__ = ['Normalizer', 'StandardScalerModel', 'StandardScaler',
            'HashingTF', 'IDFModel', 'IDF', 'Word2Vec', 'Word2VecModel']
@@ -212,7 +212,7 @@ class IDFModel(JavaVectorTransformer):
     """
     Represents an IDF model that can transform term frequency vectors.
     """
-    def transform(self, dataset):
+    def transform(self, x):
         """
         Transforms term frequency (TF) vectors to TF-IDF vectors.
 
@@ -220,12 +220,14 @@ class IDFModel(JavaVectorTransformer):
         the terms which occur in fewer than `minDocFreq`
         documents will have an entry of 0.
 
-        :param dataset: an RDD of term frequency vectors
-        :return: an RDD of TF-IDF vectors
+        :param x: an RDD of term frequency vectors or a term frequency vector
+        :return: an RDD of TF-IDF vectors or a TF-IDF vector
         """
-        if not isinstance(dataset, RDD):
-            raise TypeError("dataset should be an RDD of term frequency vectors")
-        return JavaVectorTransformer.transform(self, dataset)
+        if isinstance(x, RDD):
+            return JavaVectorTransformer.transform(self, x)
+
+        x = _convert_to_vector(x)
+        return JavaVectorTransformer.transform(self, x)
 
 
 class IDF(object):
@@ -255,6 +257,12 @@ class IDF(object):
     SparseVector(4, {1: 0.0, 3: 0.5754})
     DenseVector([0.0, 0.0, 1.3863, 0.863])
     SparseVector(4, {1: 0.0})
+    >>> model.transform(Vectors.dense([0.0, 1.0, 2.0, 3.0]))
+    DenseVector([0.0, 0.0, 1.3863, 0.863])
+    >>> model.transform([0.0, 1.0, 2.0, 3.0])
+    DenseVector([0.0, 0.0, 1.3863, 0.863])
+    >>> model.transform(Vectors.sparse(n, (1, 3), (1.0, 2.0)))
+    SparseVector(4, {1: 0.0, 3: 0.5754})
     """
     def __init__(self, minDocFreq=0):
         """