本文整理汇总了Scala中breeze.numerics.sqrt类的典型用法代码示例。如果您正苦于以下问题：Scala sqrt类的具体用法？Scala sqrt怎么用？Scala sqrt使用的例子？那么恭喜您, 这里精选的类代码示例或许可以为您提供帮助。
在下文中一共展示了sqrt类的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Scala代码示例。
示例1: RelationWithItemToItem
//设置package包名称以及导入依赖的类
package com.bigchange.mllib
import breeze.numerics.{sqrt, pow}
import org.apache.spark.{HashPartitioner, SparkConf, SparkContext}
object RelationWithItemToItem {
def main(args: Array[String]) {
val sc = new SparkContext(new SparkConf()
.setAppName("Item to Item")
.setMaster("local"))
// announce the top number of items to get
val topK = 2
val userItem = sc.textFile("/rating.dat")
.map(_.split("\t")).map(x =>(x(0),x(1),x(2))).distinct().cache()
// cal item -> (user,rating) and item -> sqrt(ratings)
val itemUser = userItem.map(x => (x._2,(x._1,x._3.toDouble))).partitionBy(new HashPartitioner(20))
// sqrt : ??? rating ??
val itemPowSqrt = userItem.map(x => (x._2,pow(x._3.toDouble,2.0))).reduceByKey(_+_).mapValues(x => sqrt(x))
// cal item -> ((user,rating),sqrt(ratings)) => user -> (item,rating/sqrt(ratings))
val userItemSqrt = itemUser.join(itemPowSqrt).map(x =>{
val item = x._1
val sqrtRatings = x._2._2
val user = x._2._1._1
val rating = x._2._1._2
(user,(item,rating / sqrtRatings))
})
// cal the relation of item to item in user dimension => get the score of item to item which connection the relation of items
val itemToItem = userItemSqrt.join(userItemSqrt).map(x =>{
val item1 = x._2._1._1
val rating1 = x._2._1._2
val item2 = x._2._2._1
val rating2 = x._2._2._2
val score = rating1 * rating2
if(item1 == item2){
((item1,item2),-1.0)
}else{
((item1,item2),score)
}
})
itemToItem.reduceByKey(_+_).map(x => (x._1._1,(x._1._2,x._2))).groupByKey().foreach(x => {
val sourceItem = x._1
val topItem = x._2.toList.filter(_._2 > 0).sortWith(_._2 > _._2).take(topK)
println(s"item = $sourceItem,topK relative item list:$topItem")
})
sc.stop()
}
}