Github user mateiz commented on a diff in the pull request:
https://github.com/apache/spark/pull/685#discussion_r13171027
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/util/NumericParser.scala ---
@@ -0,0 +1,121 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.mllib.util
+
+import java.util.StringTokenizer
+
+import scala.collection.mutable.{ArrayBuffer, ListBuffer}
+
+import org.apache.spark.SparkException
+
+/**
+ * Simple parser for a numeric structure consisting of three types:
+ *
+ * - number: a double in Java's floating number format
+ * - array: an array of numbers stored as `[v0,v1,...,vn]`
+ * - tuple: a list of numbers, arrays, or tuples stored as `(...)`
+ */
+private[mllib] object NumericParser {
+
+ /** Parses a string into a Double, an Array[Double], or a Seq[Any]. */
+ def parse(s: String): Any = {
+ val tokenizer = new StringTokenizer(s, "()[],", true)
+ if (tokenizer.hasMoreTokens()) {
+ val token = tokenizer.nextToken()
+ if (token == "(") {
+ parseTuple(tokenizer)
+ } else if (token == "[") {
+ parseArray(tokenizer)
+ } else {
+ // expecting a number
+ parseDouble(token)
+ }
+ } else {
+ throw new SparkException(s"Cannot find any token from the input
string.")
+ }
+ }
+
+ private def parseArray(tokenizer: StringTokenizer): Array[Double] = {
+ val values = ArrayBuffer.empty[Double]
+ var parsing = true
+ var allowComma = false
+ var token: String = null
+ while (parsing && tokenizer.hasMoreTokens()) {
+ token = tokenizer.nextToken()
+ if (token == "]") {
+ parsing = false
+ } else if (token == ",") {
+ if (allowComma) {
+ allowComma = false
+ } else {
+ throw new SparkException("Found a ',' at a wrong position.")
+ }
+ } else {
+ // expecting a number
+ values.append(parseDouble(token))
+ allowComma = true
+ }
+ }
+ if (parsing) {
+ throw new SparkException(s"An array must end with ']'.")
+ }
+ values.toArray
+ }
+
+ private def parseTuple(tokenizer: StringTokenizer): Seq[_] = {
+ val items = ListBuffer.empty[Any]
+ var parsing = true
+ var allowComma = false
+ var token: String = null
+ while (parsing && tokenizer.hasMoreTokens()) {
+ token = tokenizer.nextToken()
+ if (token == "(") {
+ items.append(parseTuple(tokenizer))
+ allowComma = true
+ } else if (token == "[") {
+ items.append(parseArray(tokenizer))
+ allowComma = true
+ } else if (token == ",") {
+ if (allowComma) {
+ allowComma = false
+ } else {
+ throw new SparkException("Found a ',' at a wrong position.")
+ }
+ } else if (token == ")") {
+ parsing = false
+ } else {
+ // expecting a number
+ items.append(parseDouble(token))
+ allowComma = true
+ }
+ }
+ if (parsing) {
+ throw new SparkException(s"A tuple must end with ')'.")
+ }
+ items.toSeq
--- End diff --
Is this conversion necessary? ListBuffer is likely also a Seq
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