What about putting the mappings into their own relation? I tried this with
0.9.0:
example.txt:
a,1
a,2
b,2
c,1
d,3
d,4
mapping.txt:
1,one
2,two
3,three
4,four
MAPPINGS = LOAD 'mapping.txt' USING PigStorage(',') AS
(number:int,name:chararray);
EXAMPLE_SOURCE = LOAD 'example.txt' USING PigStorage(',') AS
(item:chararray,number:int);
MAPPED = JOIN EXAMPLE_SOURCE BY number LEFT OUTER, MAPPINGS BY number;
PRETTY = FOREACH MAPPED GENERATE item, name;
DUMP PRETTY;
(a,one)
(c,one)
(a,two)
(b,two)
(d,three)
(d,four)
--
Ryan Hoegg
On Wed, Sep 14, 2011 at 3:27 PM, Eli Finkelshteyn <[email protected]>wrote:
> Hi,
> I'd like to generate based on exclusive conditions (something like the CASE
> statement in SQL). An example:
>
> Say I have data that looks like:
>
> (a, 1)
> (a, 2)
> (b, 2)
> (c, 1)
> (d, 3)
> (d, 4)
>
> And I want to just convert each of the numbers to their written forms to
> get:
>
> (a, one)
> (a, two)
> (b, two)
> (c, one)
> (d, three)
> (d, four)
>
> Would I need to write a udf for that, or is there some simple way to do it
> using cases? I know I can do a bunch of bidirectional generates one on top
> of the other to achieve this, like:
>
> FOREACH rel GENERATE $0, (($1==1) ? 'one' : (($1 == 2) ? 'two' : (($1 == 3)
> ? 'three' : 'four')));
>
> but that seems too messy. I'd appreciate any advice.
>
> Thanks!
> Eli
>
>
>
