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From wzhfy <...@git.apache.org>
Subject [GitHub] spark pull request #18323: [SPARK-21117][SQL] Built-in SQL Function Support ...
Date Thu, 22 Jun 2017 03:00:20 GMT
Github user wzhfy commented on a diff in the pull request:

    https://github.com/apache/spark/pull/18323#discussion_r123410671
  
    --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/MathUtils.scala
---
    @@ -0,0 +1,58 @@
    +/*
    + * 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.sql.catalyst.util
    +
    +import org.apache.spark.sql.AnalysisException
    +
    +object MathUtils {
    +
    +  /**
    +   *  Returns the bucket number into which
    +   *  the value of this expression would fall after being evaluated.
    +   *
    +   * @param expr id the expression for which the histogram is being created
    +   * @param minValue is an expression that resolves
    +   *                 to the minimum end point of the acceptable range for expr
    +   * @param maxValue is an expression that resolves
    +   *                 to the maximum end point of the acceptable range for expr
    +   * @param numBucket is an An expression that resolves to
    +   *                  a constant indicating the number of buckets
    +   * @return Returns an long between 0 and numBucket+1 by mapping the expr into buckets
defined by
    +   *         the range [minValue, maxValue]
    +   */
    +  def widthBucket(expr: Double, minValue: Double, maxValue: Double, numBucket: Long):
Long = {
    +
    +    if (numBucket <= 0) {
    +      throw new AnalysisException(s"The num of bucket must be greater than 0, but got
${numBucket}")
    +    }
    +
    +    val lower: Double = Math.min(minValue, maxValue)
    +    val upper: Double = Math.max(minValue, maxValue)
    +
    +    val preResult: Long = if (expr < lower) {
    +      0
    +    } else if (expr >= upper) {
    +      Math.addExact(numBucket, 1)
    +    } else {
    +      (numBucket.toDouble * (expr - lower) / (upper - lower) + 1).toLong
    +    }
    +
    +    val result = if (minValue > maxValue) (numBucket - preResult) + 1 else preResult
    +    result
    --- End diff --
    
    nit: `if (minValue > maxValue) (numBucket - preResult) + 1 else preResult`


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