写出鸢尾花KNN的scala伪代码
时间: 2023-07-09 13:40:16 浏览: 111
knn来实现鸢尾花分类
下面是鸢尾花KNN算法的Scala伪代码:
```scala
//定义一个函数,用于计算两个样本之间的欧式距离
def euclideanDistance(x1: Array[Double], x2: Array[Double]): Double = {
var distance = 0.0
for (i <- x1.indices) {
distance += Math.pow(x1(i) - x2(i), 2)
}
Math.sqrt(distance)
}
//定义一个函数,用于进行KNN分类
def knnClassify(trainData: Array[(Array[Double], String)], testData: Array[Double], k: Int): String = {
//计算测试样本与所有训练样本之间的距离,并按照距离从小到大排序
val distances = trainData.map { case (features, label) => (euclideanDistance(features, testData), label) }
val sortedDistances = distances.sortBy(_._1)
//选取距离最近的k个样本,并统计它们的类别
val topK = sortedDistances.take(k)
val labels = topK.map(_._2)
val labelCounts = labels.groupBy(identity).mapValues(_.length)
//采用多数表决的方式确定测试样本的类别
val predictedLabel = labelCounts.maxBy(_._2)._1
predictedLabel
}
//读取鸢尾花数据集
val data = spark.read.format("csv")
.option("header", "true")
.option("inferSchema", "true")
.load("iris.csv")
.rdd
.map(row => (Array(row.getDouble(0), row.getDouble(1), row.getDouble(2), row.getDouble(3)), row.getString(4)))
.collect()
//将数据集分为训练集和测试集
val trainData = data.take((0.7 * data.length).toInt)
val testData = data.drop((0.7 * data.length).toInt)
//对测试集进行分类,并计算分类准确率
val k = 5
var correctCount = 0
for ((features, label) <- testData) {
val predictedLabel = knnClassify(trainData, features, k)
if (predictedLabel == label) {
correctCount += 1
}
}
val accuracy = correctCount.toDouble / testData.length
println(s"Accuracy: $accuracy")
```
注意:以上代码仅为伪代码,需要根据实际情况进行调整和修改。
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