Github user jkbradley commented on a diff in the pull request:
https://github.com/apache/spark/pull/12498#discussion_r60305477
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/feature/HashingTF.scala ---
@@ -97,3 +126,41 @@ class HashingTF(val numFeatures: Int) extends
Serializable {
dataset.rdd.map(this.transform).toJavaRDD()
}
}
+
+object HashingTF {
+
+ private[spark] val Native: String = "native"
+
+ private[spark] val Murmur3: String = "murmur3"
+
+ private[spark] val supportedHashAlgorithms = Set(Native, Murmur3)
+
+ private val seed = 42
+
+ /**
+ * Calculate a hash code value for the term object using the native
Scala implementation.
+ */
+ private[spark] def nativeHash(term: Any): Int = term.##
+
+ /**
+ * Calculate a hash code value for the term object using
+ * Austin Appleby's MurmurHash 3 algorithm (MurmurHash3_x86_32).
+ */
+ private[spark] def murmur3Hash(term: Any): Int = {
+ term match {
+ case null => seed
+ case b: Boolean => hashInt(if (b) 1 else 0, seed)
+ case b: Byte => hashInt(b, seed)
+ case s: Short => hashInt(s, seed)
+ case i: Int => hashInt(i, seed)
+ case l: Long => hashLong(l, seed)
+ case f: Float => hashInt(java.lang.Float.floatToIntBits(f), seed)
+ case d: Double => hashLong(java.lang.Double.doubleToLongBits(d),
seed)
+ case s: String =>
+ val utf8 = UTF8String.fromString(s)
+ hashUnsafeBytes(utf8.getBaseObject, utf8.getBaseOffset,
utf8.numBytes(), seed)
+ case _ => throw new SparkException("HashingTF with murmur3 algorithm
does not " +
+ "support the type of input data.")
--- End diff --
State the type of input data in the error message
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