Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/4504#discussion_r25232699
--- Diff: mllib/src/main/scala/org/apache/spark/ml/feature/Tokenizer.scala
---
@@ -39,3 +39,66 @@ class Tokenizer extends UnaryTransformer[String,
Seq[String], Tokenizer] {
override protected def outputDataType: DataType = new
ArrayType(StringType, false)
}
+
+
+/**
+ * :: AlphaComponent ::
+ * A regex based tokenizer that extracts tokens using a regex.
+ * Optional additional parameters include enabling lowercase
stabdarization, a minimum character
+ * size for tokens as well as an array of stop words to remove from the
results.
+ */
+@AlphaComponent
+class RegexTokenizer extends UnaryTransformer[String, Seq[String],
RegexTokenizer] {
+
+ val lowerCase = new BooleanParam(this,
+ "lowerCase",
+ "enable case folding to lower case",
+ Some(true))
+ def setLowercase(value: Boolean) = set(lowerCase, value)
+ def getLowercase: Boolean = get(lowerCase)
+
+ val minLength = new IntParam(this,
+ "minLength",
+ "minimum token length (excluded)",
+ Some(0))
+ def setMinLength(value: Int) = set(minLength, value)
+ def getMinLength: Int = get(minLength)
+
+ val regEx = new Param(this,
+ "regEx",
+ "RegEx used for tokenizing",
+ Some("\\p{L}+|[^\\p{L}\\s]+".r))
+ def setRegex(value: scala.util.matching.Regex) = set(regEx, value)
+ def getRegex: scala.util.matching.Regex = get(regEx)
+
+ val stopWords = new Param(this,
+ "stopWords",
+ "array of tokens to filter from results",
+ Some(Array[String]()))
+ def setStopWords(value: Array[String]) = set(stopWords, value)
+ def getStopWords: Array[String] = get(stopWords)
+
+
+ override protected def createTransformFunc(paramMap: ParamMap): String
=> Seq[String] = { x =>
+
+ var string = x
+ if (paramMap(lowerCase)) {
+ string = string.toLowerCase
+ }
+ var tokens = (paramMap(regEx) findAllIn string).toList
--- End diff --
Do not use infix
(https://cwiki.apache.org/confluence/display/SPARK/Spark+Code+Style+Guide#SparkCodeStyleGuide-InfixMethods).
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