do not output progressive validation loss for oaa with subsampling

test/RunTests

@@ -1706,3 +1706,8 @@ printf '3 |f a b c |e x y z\n2 |f a y c |e x\n' | {VW} --oaa 3 -q ef --audit
 {VW} -d train-sets/b1848_dsjson_parser_regression.txt --dsjson --cb_explore_adf -P 1
     train-sets/ref/b1848_dsjson_parser_regression.stderr
 
+# Test 190: one-against-all with subsampling
+{VW} -k --oaa 10 --oaa_subsample 5 -c --passes 10 -d train-sets/multiclass --holdout_off
+    train-sets/ref/oaa_subsample.stderr
+
+# Do not delete this line or the empty line above it

test/train-sets/ref/oaa_subsample.stderr

@@ -0,0 +1,25 @@
+Num weight bits = 18
+learning rate = 0.5
+initial_t = 0
+power_t = 0.5
+decay_learning_rate = 1
+creating cache_file = train-sets/multiclass.cache
+Reading datafile = train-sets/multiclass
+num sources = 1
+average  since         example        example  current  current  current
+loss     last          counter         weight    label  predict features
+    n.a.     n.a.            1            1.0        1        1        2
+    n.a.     n.a.            2            2.0        2        1        2
+    n.a.     n.a.            4            4.0        4        1        2
+    n.a.     n.a.            8            8.0        8        1        2
+    n.a.     n.a.           16           16.0        6        6        2
+    n.a.     n.a.           32           32.0        2        2        2
+    n.a.     n.a.           64           64.0        4        4        2
+
+finished run
+number of examples per pass = 10
+passes used = 10
+weighted example sum = 100.000000
+weighted label sum = 0.000000
+average loss = n.a.
+total feature number = 200

vowpalwabbit/multiclass.cc

@@ -157,13 +157,13 @@ void print_update_with_probability(vw& all, example& ec, uint32_t pred)
 }
 void print_update_with_score(vw& all, example& ec, uint32_t pred) { print_update<print_score>(all, ec, pred); }
 
-void finish_example(vw& all, example& ec)
+void finish_example(vw& all, example& ec, bool update_loss)
 {
   float loss = 0;
   if (ec.l.multi.label != (uint32_t)ec.pred.multiclass && ec.l.multi.label != (uint32_t)-1)
     loss = ec.weight;
 
-  all.sd->update(ec.test_only, ec.l.multi.label != (uint32_t)-1, loss, ec.weight, ec.num_features);
+  all.sd->update(ec.test_only, update_loss && (ec.l.multi.label != (uint32_t)-1), loss, ec.weight, ec.num_features);
 
   for (int sink : all.final_prediction_sink)
     if (!all.sd->ldict)

vowpalwabbit/multiclass.h

@@ -22,11 +22,17 @@ extern label_parser mc_label;
 void print_update_with_probability(vw& all, example& ec, uint32_t prediction);
 void print_update_with_score(vw& all, example& ec, uint32_t prediction);
 
-void finish_example(vw& all, example& ec);
+void finish_example(vw& all, example& ec, bool update_loss);
 
 template <class T>
 void finish_example(vw& all, T&, example& ec)
 {
-  finish_example(all, ec);
+  finish_example(all, ec, true);
+}
+
+template <class T>
+void finish_example_without_loss(vw& all, T&, example& ec)
+{
+  finish_example(all, ec, false);
 }
 }  // namespace MULTICLASS

vowpalwabbit/oaa.cc

@@ -278,8 +278,10 @@ LEARNER::base_learner* oaa_setup(options_i& options, vw& all)
     l = &LEARNER::init_multiclass_learner(data, base, predict_or_learn<true, false, false, false>,
         predict_or_learn<false, false, false, false>, all.p, data->k, prediction_type::multiclass);
 
-  if (data_ptr->num_subsample > 0)
+  if (data_ptr->num_subsample > 0) {
     l->set_learn(learn_randomized);
+    l->set_finish_example(MULTICLASS::finish_example_without_loss<oaa>);
+  }
   l->set_finish(finish);
 
   return make_base(*l);