RDD编程练习

一、filter,map,flatmap练习：

1.读文本文件生成RDD lines

lines = sc.textFile('file:///home/hadoop/word.txt')

lines.collect()

2.将一行一行的文本分割成单词 words

words=lines.flatMap(lambda line:line.split())

words.collect()

3.全部转换为小写

words=lines.flatMap(lambda line:line.lower().split())

words.collect()

4.去掉长度小于3的单词

words=lines.flatMap(lambda line:line.split()).filter(lambda line:len(line)>3)

words.collect()

5.去掉停用词

  1.准备停用词文本：

lines = sc.textFile('file:///home/hadoop/stopwords.txt')
stop = lines.flatMap(lambda line : line.split()).collect()

stop

  2.去除停用词：

 lines=sc.textFile("file:///home/hadoop/word.txt")

words=lines.flatMap(lambda line:line.lower().split()).filter(lambda word:word not in stop)

words
words.collect()

二、groupByKey练习

6.练习一的生成单词键值对

words.map(lambda word : (word,1))

7.对单词进行分组

words.map(lambda word : (word,1)).groupByKey().collect()

8.查看分组结果

 for i in words.map(lambda word : (word,1)).groupByKey().collect()[1][1]:
print (i)

学生科目成绩文件练习：

0.数据文件上传

1.读大学计算机系的成绩数据集生成RDD

lines = sc.textFile('file:///home/hadoop/chapter4-data01.txt')

lines.take(6)

2.按学生汇总全部科目的成绩

groupByName=lines.map(lambda line:line.split(',')).map(lambda line:(line[0],(line[1],line[2]))).groupByKey()

groupByName.take(6)

 

groupByName.first()

for i in groupByName.first()[1]:
... print(i)

 

3.按科目汇总学生的成绩

groupByCourse=lines.map(lambda line:line.split(',')).map(lambda line:(line[1],(line[0],line[2]))).groupByKey()

 groupByCourse.first()

for i in groupByCourse.first()[1]:
... print(i)