Pig Example

Use case: Using Pig find the most occurred start letter.

Solution:

Case 1: Load the data into bag named "lines". The entire line is stuck to element line of type character array.

1. grunt> lines  = LOAD "/user/Desktop/data.txt" AS (line: chararray);  

Case 2: The text in the bag lines needs to be tokenized this produces one word per row.

1. grunt>tokens = FOREACH lines GENERATE flatten(TOKENIZE(line))   As token: chararray;  

Case 3: To retain the first letter of each word type the below command .This commands uses substring method to take the first character.

1. grunt>letters = FOREACH tokens  GENERATE SUBSTRING(0,1)   as letter : chararray;  

Case 4: Create a bag for unique character where the grouped bag will contain the same character for each occurrence of that character.

1. grunt>lettergrp = GROUP letters by letter;  

Case 5: The number of occurrence is counted in each group.

1. grunt>countletter  = FOREACH  lettergrp  GENERATE group  , COUNT(letters);  

Case 6: Arrange the output according to count in descending order using the commands below.

1. grunt>OrderCnt = ORDER countletter  BY  $1  DESC;  

Case 7: Limit to One to give the result.

1. grunt> result  =LIMIT    OrderCnt    1;  

Case 8: Store the result in HDFS . The result is saved in output directory under sonoo folder.

1. grunt> STORE   result   into 'home/sonoo/output';