In this tutorial, we build a binary classification model using general classifier.

Training

-- set mapred.reduce.tasks=3; -- explicitly use 3 reducers

drop table news20b_generic_model;
create table news20b_generic_model as
select 
 feature,
 voted_avg(weight) as weight
from 
 (select 
     train_classifier(
       add_bias(features), label, 
       '-loss logistic -opt AdamHD -reg l1 -iters 20'
     ) as (feature,weight)
  from
     news20b_train_x3
 ) t 
group by feature;

prediction

create or replace view news20b_generic_predict
as
select
  t.rowid, 
  sum(m.weight * t.value) as total_weight,
  case when sum(m.weight * t.value) > 0.0 then 1 else -1 end as label
from 
  news20b_test_exploded t LEFT OUTER JOIN
  news20b_generic_model m ON (t.feature = m.feature)
group by
  t.rowid;

evaluation

WITH submit as (
select 
  t.label as actual, 
  p.label as predicted
from 
  news20b_test t 
  JOIN news20b_generic_predict p
    on (t.rowid = p.rowid)
)
select 
  sum(if(actual = predicted, 1, 0)) / count(1) as accuracy
from
  submit;

0.967173738991193 (-opt AdamHD -reg l1)

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