Apache Pig - TOMAP()


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The TOMAP() function of Pig Latin is used to convert the key-value pairs into a Map.

Syntax

Given below is the syntax of the TOMAP() function.

grunt> TOMAP(key-expression, value-expression [, key-expression, valueexpression ...])

Example

Assume we have a file named employee_details.txt in the HDFS directory /pig_data/, with the following content.

employee_details.txt

001,Robin,22,newyork
002,BOB,23,Kolkata
003,Maya,23,Tokyo
004,Sara,25,London 
005,David,23,Bhuwaneshwar 
006,Maggy,22,Chennai

We have loaded this file into Pig with the relation name emp_data as shown below.

grunt> emp_data = LOAD 'hdfs://localhost:9000/pig_data/employee_details.txt' USING PigStorage(',')
   as (id:int, name:chararray, age:int, city:chararray);

Let us now take the name and age of each record as key-value pairs and convert them into map as shown below.

grunt> tomap = FOREACH emp_data GENERATE TOMAP(name, age);

Verification

You can verify the contents of the tomap relation using the Dump operator as shown below.

grunt> DUMP tomap;
  
([Robin#22])
([BOB#23])
([Maya#23])
([Sara#25]) 
([David#23])
([Maggy#22])
apache_pig_bag_tuple_functions.htm
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