CODEWITHSUNDEEP
apache-pig
dranxo
dranxo

Reputation: 3388

Simple AVG in pig groups?

I have a very simple 2-column data, with a double and a chararray:

user1 234.43
user1 432.23
user2 4321.213
etc.

I want to group by users, then compute the average of their doubles. How? Do I need a "GROUP * ALL"? I'm trying to follow Example 2 http://wiki.apache.org/pig/PigOverview , but it's not working for me. 

selfReportsAndDiscrepancies = FOREACH discrepancies1 GENERATE discrepancy,selfReportedText;
perDiscrepancy = GROUP selfReportsAndDiscrepancies BY selfReportedText;

allDiscrep = group perDiscrepancy all;

means = FOREACH allDiscrep GENERATE AVG(perDiscrepancy.discrepancy);

DUMP means;
DESCRIBE means;

gives me:

2013-04-02 17:54:06,611 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1128: Cannot find field discrepancy in group:chararray,selfReportsAndDiscrepancies:bag{:tuple(discrepancy:double,selfReportedText:chararray)}

Upvotes: 2

Views: 1215

Answers (1)

Frederic
Frederic

Reputation: 3284

I hope I understood you correctly, you want the average of the group averages:

VISITS = LOAD 'data' USING PigStorage(' ')  AS (user:chararray, number:double);
USER_VISITS = GROUP VISITS BY user;
USER_AVG = FOREACH USER_VISITS GENERATE group AS user, AVG(VISITS.number) AS average;
ALL_AVG = GROUP USER_AVG ALL;
OVERALL_AVG = FOREACH ALL_AVG GENERATE AVG(USER_AVG.average);
DUMP OVERALL_AVG;

Results in:

(2327.2715)

Upvotes: 2

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