Bring back the data loader for now.

nvflare/app_opt/xgboost/histogram_based_v2/secure_data_loader.py

@@ -0,0 +1,48 @@
+# Copyright (c) 2024, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import xgboost as xgb
+
+from nvflare.app_opt.xgboost.data_loader import XGBDataLoader
+
+COL_SECURE = 2
+ROW_SECURE = 3
+
+
+class SecureDataLoader(XGBDataLoader):
+    def __init__(self, rank: int, folder: str, data_split_mode=COL_SECURE):
+        """Reads CSV dataset and return XGB data matrix in vertical secure mode.
+
+        Args:
+            rank: Rank of the site
+            folder: Folder to find the CSV files
+        """
+        self.rank = rank
+        self.folder = folder
+        self.data_split_mode = data_split_mode
+
+    def load_data(self, client_id: str):
+
+        train_path = f"{self.folder}/site-{self.rank + 1}/train.csv"
+        valid_path = f"{self.folder}/site-{self.rank + 1}/valid.csv"
+
+        if self.rank == 0 or self.data_split_mode == ROW_SECURE:
+            label = "&label_column=0"
+        else:
+            label = ""
+
+        train_data = xgb.DMatrix(train_path + f"?format=csv{label}", data_split_mode=self.data_split_mode)
+        valid_data = xgb.DMatrix(valid_path + f"?format=csv{label}", data_split_mode=self.data_split_mode)
+
+        return train_data, valid_data