Fix slice.

include/xgboost/data.h

@@ -89,44 +89,17 @@ class MetaInfo {
    * \brief Type of each feature.  Automatically set when feature_type_names is specifed.
    */
   HostDeviceVector<FeatureType> feature_types;
-
+  /*
+   * \brief Weight of each feature, used to define the probability of each feature being
+   *        selected when using column sampling.
+   */
   HostDeviceVector<float> feature_weigths;
 
   /*! \brief default constructor */
   MetaInfo()  = default;
   MetaInfo(MetaInfo&& that) = default;
   MetaInfo& operator=(MetaInfo&& that) = default;
-  MetaInfo& operator=(MetaInfo const& that) {
-    this->num_row_ = that.num_row_;
-    this->num_col_ = that.num_col_;
-    this->num_nonzero_ = that.num_nonzero_;
-
-    this->labels_.Resize(that.labels_.Size());
-    this->labels_.Copy(that.labels_);
-
-    this->group_ptr_ = that.group_ptr_;
-
-    this->weights_.Resize(that.weights_.Size());
-    this->weights_.Copy(that.weights_);
-
-    this->base_margin_.Resize(that.base_margin_.Size());
-    this->base_margin_.Copy(that.base_margin_);
-
-    this->labels_lower_bound_.Resize(that.labels_lower_bound_.Size());
-    this->labels_lower_bound_.Copy(that.labels_lower_bound_);
-
-    this->labels_upper_bound_.Resize(that.labels_upper_bound_.Size());
-    this->labels_upper_bound_.Copy(that.labels_upper_bound_);
-
-    this->feature_weigths.Resize(that.feature_weigths.Size());
-    this->feature_weigths.Copy(that.feature_weigths);
-
-    this->feature_names = that.feature_names;
-    this->feature_type_names = that.feature_type_names;
-    this->feature_types.Resize(that.feature_types.Size());
-    this->feature_types.Copy(that.feature_types);
-    return *this;
-  }
+  MetaInfo& operator=(MetaInfo const& that) = delete;
 
   /*!
    * \brief Validate all metainfo.

src/data/data.cc

@@ -293,6 +293,9 @@ MetaInfo MetaInfo::Slice(common::Span<int32_t const> ridxs) const {
   } else {
     out.base_margin_.HostVector() = Gather(this->base_margin_.HostVector(), ridxs);
   }
+
+  out.feature_weigths.Resize(this->feature_weigths.Size());
+  out.feature_weigths.Copy(this->feature_weigths);
   return out;
 }
 

tests/python/test_dmatrix.py

@@ -75,6 +75,9 @@ def test_slice(self):
         X = rng.randn(100, 100)
         y = rng.randint(low=0, high=3, size=100)
         d = xgb.DMatrix(X, y)
+        fw = rng.randn(100)
+        d.feature_weights = fw
+
         eval_res_0 = {}
         booster = xgb.train(
             {'num_class': 3, 'objective': 'multi:softprob'}, d,
@@ -85,13 +88,17 @@ def test_slice(self):
         d.set_base_margin(predt)
 
         ridxs = [1, 2, 3, 4, 5, 6]
-        d = d.slice(ridxs)
-        sliced_margin = d.get_float_info('base_margin')
+        sliced = d.slice(ridxs)
+        np.testing.assert_equal(sliced.feature_weights, d.feature_weights)
+
+        sliced = d.slice(ridxs)
+        sliced_margin = sliced.get_float_info('base_margin')
         assert sliced_margin.shape[0] == len(ridxs) * 3
 
         eval_res_1 = {}
-        xgb.train({'num_class': 3, 'objective': 'multi:softprob'}, d,
-                  num_boost_round=2, evals=[(d, 'd')], evals_result=eval_res_1)
+        xgb.train({'num_class': 3, 'objective': 'multi:softprob'}, sliced,
+                  num_boost_round=2, evals=[(sliced, 'd')],
+                  evals_result=eval_res_1)
 
         eval_res_0 = eval_res_0['d']['merror']
         eval_res_1 = eval_res_1['d']['merror']