Fix period in evaluation monitor. (#6441)

python-package/xgboost/callback.py

@@ -621,7 +621,7 @@ def after_iteration(self, model, epoch, evals_log):
                     msg += self._fmt_metric(data, metric_name, score, stdv)
             msg += '\n'
 
-            if (epoch % self.period) != 0:
+            if (epoch % self.period) != 0 or self.period == 1:
                 rabit.tracker_print(msg)
                 self._latest = None
             else:

tests/python/test_callback.py

@@ -22,38 +22,44 @@ def setup_class(cls):
         cls.X_valid = X[split:, ...]
         cls.y_valid = y[split:, ...]
 
-    def test_evaluation_monitor(self):
-        D_train = xgb.DMatrix(self.X_train, self.y_train)
-        D_valid = xgb.DMatrix(self.X_valid, self.y_valid)
+    def run_evaluation_monitor(self, D_train, D_valid, rounds, verbose_eval):
         evals_result = {}
-        rounds = 10
-        xgb.train({'objective': 'binary:logistic',
-                   'eval_metric': 'error'}, D_train,
-                  evals=[(D_train, 'Train'), (D_valid, 'Valid')],
-                  num_boost_round=rounds,
-                  evals_result=evals_result,
-                  verbose_eval=True)
-        assert len(evals_result['Train']['error']) == rounds
-        assert len(evals_result['Valid']['error']) == rounds
-
         with tm.captured_output() as (out, err):
             xgb.train({'objective': 'binary:logistic',
                        'eval_metric': 'error'}, D_train,
                       evals=[(D_train, 'Train'), (D_valid, 'Valid')],
                       num_boost_round=rounds,
                       evals_result=evals_result,
-                      verbose_eval=2)
+                      verbose_eval=verbose_eval)
             output: str = out.getvalue().strip()
 
         pos = 0
         msg = 'Train-error'
-        for i in range(rounds // 2):
+        for i in range(rounds // int(verbose_eval)):
             pos = output.find('Train-error', pos)
             assert pos != -1
             pos += len(msg)
 
         assert output.find('Train-error', pos) == -1
 
+
+    def test_evaluation_monitor(self):
+        D_train = xgb.DMatrix(self.X_train, self.y_train)
+        D_valid = xgb.DMatrix(self.X_valid, self.y_valid)
+        evals_result = {}
+        rounds = 10
+        xgb.train({'objective': 'binary:logistic',
+                   'eval_metric': 'error'}, D_train,
+                  evals=[(D_train, 'Train'), (D_valid, 'Valid')],
+                  num_boost_round=rounds,
+                  evals_result=evals_result,
+                  verbose_eval=True)
+        assert len(evals_result['Train']['error']) == rounds
+        assert len(evals_result['Valid']['error']) == rounds
+
+        self.run_evaluation_monitor(D_train, D_valid, rounds, 2)
+        self.run_evaluation_monitor(D_train, D_valid, rounds, True)
+
     def test_early_stopping(self):
         D_train = xgb.DMatrix(self.X_train, self.y_train)
         D_valid = xgb.DMatrix(self.X_valid, self.y_valid)