中文摘要：

K-近邻（K-NN：K-nearest neighbors）是著名的数据挖掘算法,应用非常广泛.K-NN思想简单,易于实现,其计算时间复杂度和空间复杂度都是O（n）,n为训练集中包含的样例数.当训练集比较大时,特别是面对大数据集时,K-NN算法的效率会变得非常低,甚至不可行.本文用实验的方法比较了2种加速K-NN的方法,2种加速方法分别是压缩近邻（CNN：condensed nearest neighbor）方法和基于MapReduce的K-NN.具体地,在Hadoop环境下,用MapReduce编程实现了K-NN算法,并与CNN算法在8个数据集上进行了实验比较,得出了一些有价值的结论,对从事相关研究的人员具有一定的借鉴作用.

英文摘要：

K-NN（K-nearest neighbors）is a famous data mining algorithm with wide range of applications.The idea of K-NN is simple and it is easy to implement.Both computational time and space complexity of K-NN are all O（n）,where,nis the number of instances in a training set.When K-NN encountered larger training sets,especially faced with big data sets,the efficiency of K-NN becomes very low,even KNN is impracticable.Two acceleration approaches for K-nearest neighbors are experimentally compared on 8data sets.The two acceleration approaches are the CNN and MapReduce based K-NN.Specifically,in Hadoop environment,this paper implements K-NN with MapReduce,and experimentally compares with CNN on 8data sets.Some valuable conclusions are obtained,and may be useful for researchers in related fields.