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how to read fixed length files in Spark

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Expert Contributor

I have a fixed length file ( a sample is shown below) and I want to read this file using DataFrames API in Spark(1.6.0).

56 apple     TRUE 0.56
45 pear      FALSE1.34
34 raspberry TRUE 2.43
34 plum      TRUE 1.31
53 cherry    TRUE 1.4 
23 orange    FALSE2.34
56 persimmon FALSE23.2

The fixed width of each columns are 3, 10, 5, 4

Please suggest your opinion.

1 ACCEPTED SOLUTION

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Super Collaborator

Under the assumption that the file is Text and each line represent one record, you could read the file line by line and map each line to a Row. Then you can create a data frame form the RDD[Row]

something like

sqlContext.createDataFrame(sc.textFile("<file path>").map { x => getRow(x) }, schema)

I have the below basic definition for creating the Row from your line using substring. But you can use your own implementation.

def getRow(x : String) : Row={    
val columnArray = new Array[String](4)
columnArray(0)=x.substring(0,3)
columnArray(1)=x.substring(3,13)
columnArray(2)=x.substring(13,18)
columnArray(3)=x.substring(18,22)
Row.fromSeq(columnArray)  
}

If the records are not delimited by a new line, you may need to use a FixedLengthInputFormat and read the record one at a time and apply the similar logic as above. The fixedlengthinputformat.record.length in that case will be your total length, 22 in this example. Instead of textFile, you may need to read as sc.newAPIHadoopRDD

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11 REPLIES 11

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Expert Contributor

Hi Amit, I am using 1.6.0 that is installed in quick start vm from CDH 5.5.7

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New Contributor

I was so fed up with the fact that there is no proper library for fixed length format that I have created my own. You can check it out here: https://github.com/atais/Fixed-Length