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"""
Estimator Transformer Param Example.
"""
from __future__ import print_function

# $example on$
from pyspark.ml.linalg import Vectors
from pyspark.ml.classification import LogisticRegression
# $example off$
from pyspark.sql import SparkSession

if __name__ == "__main__":
    spark = SparkSession\
        .builder\
        .appName("EstimatorTransformerParamExample")\
        .getOrCreate()

    # $example on$
    # Prepare training data from a list of (label, features) tuples.
    training = spark.createDataFrame([
        (1.0, Vectors.dense([0.0, 1.1, 0.1])),
        (0.0, Vectors.dense([2.0, 1.0, -1.0])),
        (0.0, Vectors.dense([2.0, 1.3, 1.0])),
        (1.0, Vectors.dense([0.0, 1.2, -0.5]))], ["label", "features"])

    # Create a LogisticRegression instance. This instance is an Estimator.
    lr = LogisticRegression(maxIter=10, regParam=0.01)
    # Print out the parameters, documentation, and any default values.
    print("LogisticRegression parameters:\n" + lr.explainParams() + "\n")

    # Learn a LogisticRegression model. This uses the parameters stored in lr.
    model1 = lr.fit(training)

    # Since model1 is a Model (i.e., a transformer produced by an Estimator),
    # we can view the parameters it used during fit().
    # This prints the parameter (name: value) pairs, where names are unique IDs for this
    # LogisticRegression instance.
    print("Model 1 was fit using parameters: ")
    print(lr.extractParamMap())

    # We may alternatively specify parameters using a Python dictionary as a paramMap
    paramMap = {lr.maxIter: 20}
    paramMap[lr.maxIter] = 30  # Specify 1 Param, overwriting the original maxIter.
    paramMap.update({lr.regParam: 0.1, lr.threshold: 0.55})  # Specify multiple Params.

    # You can combine paramMaps, which are python dictionaries.
    paramMap2 = {lr.probabilityCol: "myProbability"}  # Change output column name
    paramMapCombined = paramMap.copy()
    paramMapCombined.update(paramMap2)

    # Now learn a new model using the paramMapCombined parameters.
    # paramMapCombined overrides all parameters set earlier via lr.set* methods.
    model2 = lr.fit(training, paramMapCombined)
    print("Model 2 was fit using parameters: ")
    print(lr.extractParamMap(extra=paramMapCombined))

    # Prepare test data
    test = spark.createDataFrame([
        (1.0, Vectors.dense([-1.0, 1.5, 1.3])),
        (0.0, Vectors.dense([3.0, 2.0, -0.1])),
        (1.0, Vectors.dense([0.0, 2.2, -1.5]))], ["label", "features"])

    # Make predictions on test data using the Transformer.transform() method.
    # LogisticRegression.transform will only use the 'features' column.
    # Note that model2.transform() outputs a "myProbability" column instead of the usual
    # 'probability' column since we renamed the lr.probabilityCol parameter previously.
    prediction = model2.transform(test)
    result = prediction.select("features", "label", "myProbability", "prediction") \
        .collect()

    for row in result:
        print("features=%s, label=%s -> prob=%s, prediction=%s"
              % (row.features, row.label, row.myProbability, row.prediction))
    # $example off$

    spark.stop()
