Question

我在本地模式下部署Spark spark-1.4.1-bin-hadoop2.6，我正在从HDFS读取输入JSON文件。但是SparkR dataFrame read.df方法的方法不行从HDFS加载数据。

1）“read.df”错误消息

data＆lt; - read.df（“/ data / sample.json”）#hdfs输入

15/09/01 18:19:38 ERROR r.RBackendHandler: loadDF on org.apache.spark.sql.api.r.SQLUtils failed
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at org.apache.spark.api.r.RBackendHandler.handleMethodCall(RBackendHandler.scala:142)
        at org.apache.spark.api.r.RBackendHandler.channelRead0(RBackendHandler.scala:74)
        at org.apache.spark.api.r.RBackendHandler.channelRead0(RBackendHandler.scala:36)
        at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:333)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:319)
        at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:333)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:319)
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:163)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:333)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:319)
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:787)
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:130)
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:511)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468)
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354)
        at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116)
        at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.NoSuchElementException: key not found: path
        at scala.collection.MapLike$class.default(MapLike.scala:228)
        at org.apache.spark.sql.sources.CaseInsensitiveMap.default(ddl.scala:467)
        at scala.collection.MapLike$class.apply(MapLike.scala:141)
        at org.apache.spark.sql.sources.CaseInsensitiveMap.apply(ddl.scala:467)
        at org.apache.spark.sql.sources.ResolvedDataSource$.apply(ddl.scala:273)
        at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:114)
        at org.apache.spark.sql.api.r.SQLUtils$.loadDF(SQLUtils.scala:147)
        at org.apache.spark.sql.api.r.SQLUtils.loadDF(SQLUtils.scala)
        ... 25 more
Error: returnStatus == 0 is not TRUE

感谢Adv。

Answer 1

data＆lt; - read.json（“/ data / sample.json”）

Answer 2

您需要调用sqlContext。

示例：

data <- read.df(sqlContext, "/data/sample.json","json")

对于一个带有people.json的dataframe.R示例，它很有用。

如何读取SparkR中的json / csv文件？

2 个答案: