Github user jkbradley commented on a diff in the pull request:
https://github.com/apache/spark/pull/20904#discussion_r180245120
--- Diff: python/pyspark/ml/stat.py ---
@@ -127,13 +113,86 @@ class Correlation(object):
def corr(dataset, column, method="pearson"):
"""
Compute the correlation matrix with specified method using dataset.
+
+ :param dataset:
+ A Dataset or a DataFrame.
+ :param column:
+ The name of the column of vectors for which the correlation
coefficient needs
+ to be computed. This must be a column of the dataset, and it
must contain
+ Vector objects.
+ :param method:
+ String specifying the method to use for computing correlation.
+ Supported: `pearson` (default), `spearman`.
+ :return:
+ A DataFrame that contains the correlation matrix of the column
of vectors. This
+ DataFrame contains a single row and a single column of name
+ '$METHODNAME($COLUMN)'.
"""
sc = SparkContext._active_spark_context
javaCorrObj = _jvm().org.apache.spark.ml.stat.Correlation
args = [_py2java(sc, arg) for arg in (dataset, column, method)]
return _java2py(sc, javaCorrObj.corr(*args))
+class KolmogorovSmirnovTest(object):
+ """
+ .. note:: Experimental
+
+ Conduct the two-sided Kolmogorov Smirnov (KS) test for data sampled
from a continuous
+ distribution.
+
+ By comparing the largest difference between the empirical cumulative
+ distribution of the sample data and the theoretical distribution we
can provide a test for the
+ the null hypothesis that the sample data comes from that theoretical
distribution.
+
+ >>> from pyspark.ml.stat import KolmogorovSmirnovTest
+ >>> dataset = [[-1.0], [0.0], [1.0]]
+ >>> dataset = spark.createDataFrame(dataset, ['sample'])
+ >>> ksResult = KolmogorovSmirnovTest.test(dataset, 'sample', 'norm',
0.0, 1.0).first()
+ >>> round(ksResult.pValue, 3)
+ 1.0
+ >>> round(ksResult.statistic, 3)
+ 0.175
+ >>> dataset = [[2.0], [3.0], [4.0]]
+ >>> dataset = spark.createDataFrame(dataset, ['sample'])
+ >>> ksResult = KolmogorovSmirnovTest.test(dataset, 'sample', 'norm',
3.0, 1.0).first()
+ >>> round(ksResult.pValue, 3)
+ 1.0
+ >>> round(ksResult.statistic, 3)
+ 0.175
+
+ .. versionadded:: 2.4.0
+
+ """
+ @staticmethod
+ @since("2.4.0")
+ def test(dataset, sampleCol, distName, *params):
+ """
+ Perform a Kolmogorov-Smirnov test using dataset.
--- End diff --
Can you please make this match the text in the Scala doc?
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