[SPARK-15141][EXAMPLE][DOC] Update OneVsRest Examples

## What changes were proposed in this pull request?
1, Add python example for OneVsRest
2, remove args-parsing

## How was this patch tested?
manual tests
`./bin/spark-submit examples/src/main/python/ml/one_vs_rest_example.py`

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #12920 from zhengruifeng/ovr_pe.

1 files changed, 68 insertions, 0 deletions

diff --git a/examples/src/main/python/ml/one_vs_rest_example.py b/examples/src/main/python/ml/one_vs_rest_example.py
new file mode 100644
index 0000000000..971156d0dd
--- /dev/null
+++ b/examples/src/main/python/ml/one_vs_rest_example.py
@@ -0,0 +1,68 @@
+#
+# 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 __future__ import print_function
+
+# $example on$
+from pyspark.ml.classification import LogisticRegression, OneVsRest
+from pyspark.ml.evaluation import MulticlassClassificationEvaluator
+# $example off$
+from pyspark.sql import SparkSession
+
+"""
+An example of Multiclass to Binary Reduction with One Vs Rest,
+using Logistic Regression as the base classifier.
+Run with:
+  bin/spark-submit examples/src/main/python/ml/one_vs_rest_example.py
+"""
+
+
+if __name__ == "__main__":
+    spark = SparkSession \
+        .builder \
+        .appName("PythonOneVsRestExample") \
+        .getOrCreate()
+
+    # $example on$
+    # load data file.
+    inputData = spark.read.format("libsvm") \
+        .load("data/mllib/sample_multiclass_classification_data.txt")
+
+    # generate the train/test split.
+    (train, test) = inputData.randomSplit([0.8, 0.2])
+
+    # instantiate the base classifier.
+    lr = LogisticRegression(maxIter=10, tol=1E-6, fitIntercept=True)
+
+    # instantiate the One Vs Rest Classifier.
+    ovr = OneVsRest(classifier=lr)
+
+    # train the multiclass model.
+    ovrModel = ovr.fit(train)
+
+    # score the model on test data.
+    predictions = ovrModel.transform(test)
+
+    # obtain evaluator.
+    evaluator = MulticlassClassificationEvaluator(metricName="precision")
+
+    # compute the classification error on test data.
+    precision = evaluator.evaluate(predictions)
+    print("Test Error : " + str(1 - precision))
+    # $example off$
+
+    spark.stop()