标签：lte 长度 split 去掉 col nbsp div 图片 bsp
一、词频统计：
1.读文本文件生成RDD lines
lines = sc.textFile(‘file:///home/hadoop/word.txt‘)
2.将一行一行的文本分割成单词 words flatmap()
words=lines.flatMap(lambda line:line.split())
words.collect()
3.全部转换为小写 lower()
words=lines.flatMap(lambda line:line.lower().split()) words.collect()
4.去掉长度小于3的单词 filter()
words=words.filter(lambda word:len(word)>3)
words.collect()
5.去掉停用词
with open(‘/home/hadoop/stopwords.txt‘) as f: stops=f.read().split() words=words.filter(lambda word:word not in stops) words.count() words.collect()
6.转换成键值对 map()
words=words.map(lambda word:(word,1))
7.统计词频 reduceByKey()
words=words.reduceByKey(lambda a,b:a+b)
8.按字母顺序排序 sortBy(f)
words=words.sortBy(lambda word:word[0]) words.collect()
9.按词频排序 sortByKey()
words=words.sortByKey()
words.collect()
二、学生课程分数案例
lines = sc.textFile(‘file:///home/hadoop/chapter4-data01.txt‘)
lines.take(5)
1.总共有多少学生？map(), distinct(), count()
lines.map(lambda line : line.split(‘,‘)[0]).distinct().count()
2.开设了多少门课程？
lines.map(lambda line : line.split(‘,‘)[1]).distinct().count()
3.每个学生选修了多少门课？map(), countByKey()
lines.map(lambda line : line.split(‘,‘)).map(lambda line:(line[0],(line[1],line[2]))).countByKey()
4.每门课程有多少个学生选？map(), countByValue()
lines.map(lambda line : line.split(‘,‘)).map(lambda line : (line[1])).countByValue()
5.Les选修了几门课？每门课多少分？filter(), map() RDD
lines.filter(lambda line:"Les" in line).map(lambda line:line.split(‘,‘)).collect()
6.Les选修了几门课？每门课多少分？map(),lookup() list
lines.map(lambda line:line.split(‘,‘)).map(lambda line:(line[0],line[1])).lookup("Les") lines.map(lambda line:line.split(‘,‘)).map(lambda line:(line[0],line[2])).lookup("Les")
7.Les的成绩按分数大小排序。filter(), map(), sortBy()
lines.filter(lambda line:"Les" in line).map(lambda line:line.split(‘,‘)).sortBy(lambda line:(line[2])).collect()
8.Les的平均分。map(),lookup(),mean()
import numpy as np meanlist=lines.map(lambda line:line.split(‘,‘)).map(lambda line:(line[0],line[2])).lookup("Les") np.mean([int(x) for x in meanlist])
标签：lte 长度 split 去掉 col nbsp div 图片 bsp
原文地址：https://www.cnblogs.com/shawncs/p/14673296.html
