a9a

http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/binary.html#a9a

Data preparation

$ wget http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/binary/a9a
$ wget http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/binary/a9a.t
scala> :paste
park.read.format("libsvm").load("a9a")
  .select($"label", to_hivemall_features($"features").as("features"))
  .createOrReplaceTempView("rawTrainTable")

val (max, min) = sql("SELECT MAX(label), MIN(label) FROM rawTrainTable").collect.map {
  case Row(max: Double, min: Double) => (max, min)
}.head

// `label` must be [0.0, 1.0]
sql(s"""
  CREATE OR REPLACE TEMPORARY VIEW trainTable AS
    SELECT rescale(label, $min, $max) AS label, features
      FROM rawTrainTable
""")

scala> trainDf.printSchema
root
 |-- label: float (nullable = true)
 |-- features: vector (nullable = true)

scala> :paste
spark.read.format("libsvm").load("a9a.t")
  .select($"label", to_hivemall_features($"features").as("features"))
  .createOrReplaceTempView("rawTestTable")

sql(s"""
  CREATE OR REPLACE TEMPORARY VIEW testTable AS
    SELECT
        rowid() AS rowid,
        rescale(label, $min, $max) AS target,
        features
      FROM
        rawTestTable
""")

// Caches data to fix row IDs
sql("CACHE TABLE testTable")

sql("""
  CREATE OR REPLACE TEMPORARY VIEW testTable_exploded AS
    SELECT
        rowid,
        target,
        extract_feature(ft) AS feature,
        extract_weight(ft) AS value
      FROM (
        SELECT
            rowid,
            target,
            explode(features) AS ft
          FROM
            testTable
        )
""")

scala> testDf.printSchema
root
 |-- rowid: string (nullable = true)
 |-- target: float (nullable = true)
 |-- feature: string (nullable = true)
 |-- value: double (nullable = true)

Tutorials

[Logistic Regression]

Training

scala> :paste
sql("""
  CREATE OR REPLACE TEMPORARY VIEW modelTable AS
    SELECT
        feature, AVG(weight) AS weight
      FROM (
        SELECT
            train_logistic_regr(add_bias(features), label) AS (feature, weight)
          FROM
            trainTable
          )
      GROUP BY
        feature
""")

Test

scala> :paste
sql("""
  CREATE OR REPLACE TEMPORARY VIEW predicted AS
    SELECT
        rowid,
        CASE
          WHEN sigmoid(sum(weight * value)) > 0.50 THEN 1.0
          ELSE 0.0
        END AS predicted
      FROM
        testTable_exploded t LEFT OUTER JOIN modelTable m
          ON t.feature = m.feature
      GROUP BY
        rowid
""")

Evaluation

val num_test_instances = spark.table("testTable").count

sql(s"""
  SELECT
      count(1) / $num_test_instances AS eval
    FROM
      predicted p INNER JOIN testTable t
        ON p.rowid = t.rowid
    WHERE
      p.predicted = t.target
""")

+------------------+
|              eval|
+------------------+
|0.8327921286841418|
+------------------+

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