I have a seemingly simple Pig generate and then filter issue - apache-pig

Question

I am trying to run a simple Pig script on a simple csv file and I can not get FILTER to do what I want. I have a test.csv file that looks like this:
john,12,44,,0
bob,14,56,5,7
dave,13,40,5,5
jill,8,,,6
Here is my script that does not work:
people = LOAD 'hdfs:/whatever/test.csv' using PigStorage(',');
data = FOREACH people GENERATE $0 AS name:chararray, $1 AS first:int, $4 AS second:int;
filtered = FILTER data BY first == 13;
DUMP filtered;
When I dump data, everything looks good. I get the name and the first and last integer as expected. When I describe the data, everything looks good:
data: {name: bytearray,first: int,second: int}
When I try and filter out data by the first value being 13, I get nothing. DUMP filtered simply returns nothing. Oddly enough, if I change it to first > 13, then all "rows" will print out.
However, this script works:
peopletwo = LOAD 'hdfs:/whatever/test.csv' using PigStorage(',') AS (f1:chararray,f2:int,f3:int,f4:int,f5:int);
datatwo = FOREACH peopletwo GENERATE $0 AS name:chararray, $1 AS first:int, $4 AS second:int;
filteredtwo = FILTER datatwo BY first == 13;
DUMP filteredtwo;
What is the difference between filteredtwo and filtered (or data and datatwo for that matter)? I want to know why the new relation obtained using GENERATE (i.e. data) won't filter in the first script as one would expect.

Answer 1

Specify the datatype in the load itself.See below
people = LOAD 'test5.csv' USING PigStorage(',') as (f1:chararray,f2:int,f3:int,f4:int,f5:int);
filtered = FILTER people BY f2 == 13;
DUMP filtered;
Output
Changing the filter to use > gives
filtered = FILTER people BY f2 > 13;
Output
EDIT
When converting from bytearray you will have to explicitly cast the value of the fields in the FOREACH.This works.
people = LOAD 'test5.csv' USING PigStorage(',');
data = FOREACH people GENERATE $0 AS name:chararray,(int)$1 AS f1,(int)$4 AS f2;
filtered = FILTER data BY f1 == 13;
DUMP filtered;