Doing word count in pig - apache-pig

Question

I have data already processed in following form:
( id ,{ bag of words})
So for example:
(foobar, {(foo), (foo),(foobar),(bar)})
(foo,{(bar),(bar)})
and so on..
describe processed gives me:
processed: {id: chararray,tokens: {tuple_of_tokens: (token: chararray)}}
Now what I want is.. also count the number of times a word appears in this data and output it as
foobar, foo, 2
foobar,foobar,1
foobar,bar,1
foo,bar,2
and so on...
How do I do this in pig?

Answer 1

Though you can do this in pure pig, it should be much more efficient to do this with a UDF. Something along the lines of:
#outputschema('wordcounts: {T:(word:chararray, count:int)}')
def generate_wordcount(BAG):
d = {}
for word in BAG:
if word in d:
d[word] += 1
else:
d[word] = 1
return d.items()
You can then use this UDF like this:
REGISTER 'myudfs.py' USING jython AS myudfs ;
-- A: (id, words: {T:(word:chararray)})
B = FOREACH A GENERATE id, FLATTEN(myudfs.generate_wordcount(words)) ;

Answer 2

Try this:
$ cat input
foobar foo
foobar foo
foobar foobar
foobar bar
foo bar
foo bar
--preparing
inputs = LOAD 'input' AS (first: chararray, second: chararray);
grouped = GROUP inputs BY first;
formatted = FOREACH grouped GENERATE group, inputs.second AS second;
--what you need
flattened = FOREACH formatted GENERATE group, FLATTEN(second);
result = FOREACH (GROUP flattened BY (group, second)) GENERATE FLATTEN(group), COUNT(flattened);
DUMP result;
Output:
(foo,bar,2)
(foobar,bar,1)
(foobar,foo,2)
(foobar,foobar,1)