Repository: spark Updated Branches: refs/heads/master 6e77105e1 -> c8696337e
[SPARK-7556] [ML] [DOC] Add user guide for spark.ml Binarizer, including Scala, Java and Python examples JIRA: https://issues.apache.org/jira/browse/SPARK-7556 Author: Liang-Chi Hsieh <[email protected]> Closes #6116 from viirya/binarizer_doc and squashes the following commits: 40cb677 [Liang-Chi Hsieh] Better print out. 5b7ef1d [Liang-Chi Hsieh] Make examples more clear. 1bf9c09 [Liang-Chi Hsieh] For comments. 6cf8cba [Liang-Chi Hsieh] Add user guide for Binarizer. Project: http://git-wip-us.apache.org/repos/asf/spark/repo Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/c8696337 Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/c8696337 Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/c8696337 Branch: refs/heads/master Commit: c8696337e2a5878f3171eb574c0a1365d45814c9 Parents: 6e77105 Author: Liang-Chi Hsieh <[email protected]> Authored: Fri May 15 15:05:04 2015 -0700 Committer: Joseph K. Bradley <[email protected]> Committed: Fri May 15 15:05:04 2015 -0700 ---------------------------------------------------------------------- docs/ml-features.md | 84 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/spark/blob/c8696337/docs/ml-features.md ---------------------------------------------------------------------- diff --git a/docs/ml-features.md b/docs/ml-features.md index 0cbebcb..5df61dd 100644 --- a/docs/ml-features.md +++ b/docs/ml-features.md @@ -183,6 +183,90 @@ for words_label in wordsDataFrame.select("words", "label").take(3): </div> </div> +## Binarizer + +Binarization is the process of thresholding numerical features to binary features. As some probabilistic estimators make assumption that the input data is distributed according to [Bernoulli distribution](http://en.wikipedia.org/wiki/Bernoulli_distribution), a binarizer is useful for pre-processing the input data with continuous numerical features. + +A simple [Binarizer](api/scala/index.html#org.apache.spark.ml.feature.Binarizer) class provides this functionality. Besides the common parameters of `inputCol` and `outputCol`, `Binarizer` has the parameter `threshold` used for binarizing continuous numerical features. The features greater than the threshold, will be binarized to 1.0. The features equal to or less than the threshold, will be binarized to 0.0. The example below shows how to binarize numerical features. + +<div class="codetabs"> +<div data-lang="scala" markdown="1"> +{% highlight scala %} +import org.apache.spark.ml.feature.Binarizer +import org.apache.spark.sql.DataFrame + +val data = Array( + (0, 0.1), + (1, 0.8), + (2, 0.2) +) +val dataFrame: DataFrame = sqlContext.createDataFrame(data).toDF("label", "feature") + +val binarizer: Binarizer = new Binarizer() + .setInputCol("feature") + .setOutputCol("binarized_feature") + .setThreshold(0.5) + +val binarizedDataFrame = binarizer.transform(dataFrame) +val binarizedFeatures = binarizedDataFrame.select("binarized_feature") +binarizedFeatures.collect().foreach(println) +{% endhighlight %} +</div> + +<div data-lang="java" markdown="1"> +{% highlight java %} +import com.google.common.collect.Lists; + +import org.apache.spark.api.java.JavaRDD; +import org.apache.spark.ml.feature.Binarizer; +import org.apache.spark.sql.DataFrame; +import org.apache.spark.sql.Row; +import org.apache.spark.sql.RowFactory; +import org.apache.spark.sql.types.DataTypes; +import org.apache.spark.sql.types.Metadata; +import org.apache.spark.sql.types.StructField; +import org.apache.spark.sql.types.StructType; + +JavaRDD<Row> jrdd = jsc.parallelize(Lists.newArrayList( + RowFactory.create(0, 0.1), + RowFactory.create(1, 0.8), + RowFactory.create(2, 0.2) +)); +StructType schema = new StructType(new StructField[]{ + new StructField("label", DataTypes.DoubleType, false, Metadata.empty()), + new StructField("feature", DataTypes.DoubleType, false, Metadata.empty()) +}); +DataFrame continuousDataFrame = jsql.createDataFrame(jrdd, schema); +Binarizer binarizer = new Binarizer() + .setInputCol("feature") + .setOutputCol("binarized_feature") + .setThreshold(0.5); +DataFrame binarizedDataFrame = binarizer.transform(continuousDataFrame); +DataFrame binarizedFeatures = binarizedDataFrame.select("binarized_feature"); +for (Row r : binarizedFeatures.collect()) { + Double binarized_value = r.getDouble(0); + System.out.println(binarized_value); +} +{% endhighlight %} +</div> + +<div data-lang="python" markdown="1"> +{% highlight python %} +from pyspark.ml.feature import Binarizer + +continuousDataFrame = sqlContext.createDataFrame([ + (0, 0.1), + (1, 0.8), + (2, 0.2) +], ["label", "feature"]) +binarizer = Binarizer(threshold=0.5, inputCol="feature", outputCol="binarized_feature") +binarizedDataFrame = binarizer.transform(continuousDataFrame) +binarizedFeatures = binarizedDataFrame.select("binarized_feature") +for binarized_feature, in binarizedFeatures.collect(): + print binarized_feature +{% endhighlight %} +</div> +</div> # Feature Selectors --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
