Question

我从文件中获得了RDD[String]：

val file = sc.textFile("/path/to/myData.txt")

myData的格式：

>str1_name
ATCGGKFKKVKKFKRLFFVLFLRL
FDJKALGFJVKRIKFKVKFGKLRL
...
FJDLALLLGL //the last line of str1
>str2_name
ATCGGKFKKVKKFKRLFFVLFLRL
FDJKALGFJVKRIKFKVKFGKLRL
...
FJDLALLLGL //the last line of str2
>str3_name
...

如何将数据从文件转换为结构RDD[(String, String)]？例如，

trancRDD(
(str1_name, ATCGGKFKKVKKFKRLFFVLFLRLFDJKALGFJVKRIKFKVKFGKLRL), 
(str2_name, ATCGGKFKKVKKFKRLFFVLFLRLFDJKALGFJVKRIKFKVKFGKLRL),
...
)

Answer 1

如果有定义的记录分隔符，例如“＆gt;”如上所述，这可以使用自定义Hadoop配置来完成：

import org.apache.hadoop.conf.Configuration
import org.apache.hadoop.io.{LongWritable, Text}
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat

val conf = new Configuration
conf.set("textinputformat.record.delimiter", ">")
// genome.txt contains the records provided in the question without the "..."
val dataset = sc.newAPIHadoopFile("./data/genome.txt", classOf[TextInputFormat], classOf[LongWritable], classOf[Text], conf)
val data = dataset.map(x=>x._2.toString)

我们来看看数据

data.collect
res11: Array[String] = 
Array("", "str1_name
ATCGGKFKKVKKFKRLFFVLFLRL
FDJKALGFJVKRIKFKVKFGKLRL
FJDLALLLGL 
", "str2_name
ATCGGKFKKVKKFKRLFFVLFLRL
FDJKALGFJVKRIKFKVKFGKLRL
FJDLALLLGL
")

我们可以轻松地从这个字符串

中创建记录

val records =  data.map{ multiLine => val lines = multiLine.split("\n"); (lines.head, lines.tail)}
records.collect
res14: Array[(String, Array[String])] = Array(("",Array()),
       (str1_name,Array(ATCGGKFKKVKKFKRLFFVLFLRL, FDJKALGFJVKRIKFKVKFGKLRL, FJDLALLLGL)),
       (str2_name,Array(ATCGGKFKKVKKFKRLFFVLFLRL, FDJKALGFJVKRIKFKVKFGKLRL, FJDLALLLGL)))

（使用过滤器取出第一个空记录......为读者练习）

我该怎么做才能将RDD [String]转换为RDD [（String，String）]？

1 个答案: