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我正在尝试使用 Amazon EMR 上的 Rstudio 中的 rmr 包将数据帧从 R 写入 HDFS。我正在关注的教程是 http://blogs.aws.amazon.com/bigdata/post/Tx37RSKRFDQNTSL/Statistical-Analysis-with-Open-Source-R-and-RStudio-on-Amazon-EMR

我写的代码是

    Sys.setenv(HADOOP_CMD="/home/hadoop/bin/hadoop")
    Sys.setenv(HADOOP_STREAMING="/home/hadoop/contrib/streaming/hadoop-streaming.jar")
    Sys.setenv(JAVA_HOME="/usr/java/latest/jre")

    # load librarys
    library(rmr2)
    library(rhdfs)
    library(plyrmr)

    # initiate rhdfs package
    hdfs.init()

    # a very simple plyrmr example to test the package
    library(plyrmr)
    # running code localy
    bind.cols(mtcars, carb.per.cyl = carb/cyl)
    # same code on Hadoop cluster
    to.dfs(mtcars, output="/tmp/mtcars")

我正在关注此代码教程： https ://github.com/awslabs/emr-bootstrap-actions/blob/master/R/Hadoop/examples/biganalysiss_example.R

Tha hadoop 版本是 Cloudera CDH5。我还适当地设置了环境变量。

在运行上述代码时，我收到以下错误：

    > to.dfs(data,output="/tmp/cust_seg")
    15/03/09 20:00:21 ERROR streaming.StreamJob: Missing required options: input, output
    Usage: $HADOOP_HOME/bin/hadoop jar \
      $HADOOP_HOME/hadoop-streaming.jar [options]
    Options:
      -input    <path>     DFS input file(s) for the Map step
      -output   <path>     DFS output directory for the Reduce step
      -mapper   <cmd|JavaClassName>      The streaming command to run
      -combiner <JavaClassName> Combiner has to be a Java class
      -reducer  <cmd|JavaClassName>      The streaming command to run
      -file     <file>     File/dir to be shipped in the Job jar file
      -inputformat TextInputFormat(default)|SequenceFileAsTextInputFormat|JavaClassName Optional.
      -outputformat TextOutputFormat(default)|JavaClassName  Optional.
      -partitioner JavaClassName  Optional.
      -numReduceTasks <num>  Optional.
      -inputreader <spec>  Optional.
      -cmdenv   <n>=<v>    Optional. Pass env.var to streaming commands
      -mapdebug <path>  Optional. To run this script when a map task fails 
      -reducedebug <path>  Optional. To run this script when a reduce task fails 
      -verbose

    Generic options supported are
    -conf <configuration file>     specify an application configuration file
    -D <property=value>            use value for given property
    -fs <local|namenode:port>      specify a namenode
    -jt <local|resourcemanager:port>    specify a ResourceManager
    -files <comma separated list of files>    specify comma separated files to be copied to the map reduce cluster
    -libjars <comma separated list of jars>    specify comma separated jar files to include in the classpath.
    -archives <comma separated list of archives>    specify comma separated archives to be unarchived on the compute machines.

    The general command line syntax is
    bin/hadoop command [genericOptions] [commandOptions]


    For more details about these options:
    Use $HADOOP_HOME/bin/hadoop jar build/hadoop-streaming.jar -info

    Streaming Job Failed!

我无法弄清楚这个问题的解决方案。如果有人能迅速提供帮助，将不胜感激。

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1 回答 1

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该错误是由于HADOOP_STREAMING您的代码中未正确设置环境变量而引起的。您应该指定完整路径以及 jar 文件名。下面的 R 代码对我来说很好。

R 代码（我使用的是 hadoop 2.4.0）

Sys.setenv("HADOOP_CMD"="/usr/local/hadoop/bin/hadoop")
Sys.setenv("HADOOP_STREAMING"="/usr/local/hadoop/share/hadoop/tools/lib/hadoop-streaming-2.4.0.jar")

# load librarys
library(rmr2)
library(rhdfs)

# initiate rhdfs package
hdfs.init()

# a very simple plyrmr example to test the package
library(plyrmr)

# running code localy
bind.cols(mtcars, carb.per.cyl = carb/cyl)

# same code on Hadoop cluster
to.dfs(mtcars, output="/tmp/mtcars")

# list the files of tmp folder
hdfs.ls("/tmp")

  permission   owner      group   size          modtime                  file
1 -rw-r--r-- manohar supergroup   1685 2015-03-22 16:12           /tmp/mtcars

希望这可以帮助。

于 2015-03-22T10:55:47.617 回答