I would like to transform a map into a field in a Pig Latin script - apache-pig

Question

The description of my tuples of my relation (A) is as follows:
{a: int, b: int, c: map[]}
the map contains only one chararray but the key is not predictable. For example, a sample of my tuples is:
(1, 100, [key.152#hello])
(8, 110, [key.3000#bonjour])
(5, 103, [key.1#hallo])
(5, 103, [])
(8, 104, [key.11#buenosdias])
...
I would like to transform my relation (A) into a B relation so the B description would be:
{a: int, b: int, c: chararray}
With my sample, it would give:
(1, 100, hello)
(8, 110, bonjour)
(5, 103, hallo)
(8, 104, buenosdias)
...
(I want to filter empty maps too)
Any ideas?
Thank you.

Answer 1

Though writing the UDF is the right solution, if you want to hack something quick following solution using Regex might help.
A = LOAD 'sample.txt' as (a:int, b:int, c:chararray);
B = FOREACH A GENERATE a, b, FLATTEN(STRSPLIT(c, '#', 2)) as (key:chararray, value:chararray);
C = FOREACH B GENERATE a, b, FLATTEN(STRSPLIT(value, ']', 2)) as (value:chararray, ignore:chararray);
D = FILTER C BY value is not null;
E = FOREACH D GENERATE a, b, value;
STORE E INTO 'output/E';
For sample input
1 100 [key.152#hello]
8 110 [key.3000#bonjour]
5 103 [key.1#hallo]
5 103 []
8 104 [key.11#buenosdias]
The above code produces following output:
1 100 hello
8 110 bonjour
5 103 hallo
8 104 buenosdias