[Model] Refactor PaddleClas module (#505)

* Refactor the PaddleClas module

* fix bug

* remove debug code

* clean unused code

* support pybind

* Update fd_tensor.h

* Update fd_tensor.cc

* temporary revert python api

* fix ci error

* fix code style problem

fastdeploy/vision/classification/ppcls/postprocessor.cc

@@ -0,0 +1,53 @@
+// Copyright (c) 2022 PaddlePaddle Authors. 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.
+
+#include "fastdeploy/vision/classification/ppcls/postprocessor.h"
+#include "fastdeploy/vision/utils/utils.h"
+
+namespace fastdeploy {
+namespace vision {
+namespace classification {
+
+PaddleClasPostprocessor::PaddleClasPostprocessor(int topk) {
+  topk_ = topk;
+  initialized_ = true;
+}
+
+bool PaddleClasPostprocessor::Run(const std::vector<FDTensor>& infer_result, std::vector<ClassifyResult>* results) {
+  if (!initialized_) {
+    FDERROR << "Postprocessor is not initialized." << std::endl;
+    return false;
+  }
+
+  int batch = infer_result[0].shape[0];
+  int num_classes = infer_result[0].shape[1];
+  const float* infer_result_data = reinterpret_cast<const float*>(infer_result[0].Data());
+ 
+  results->resize(batch);
+
+  int topk = std::min(num_classes, topk_);
+  for (int i = 0; i < batch; ++i) {
+    (*results)[i].label_ids = utils::TopKIndices(infer_result_data + i * num_classes, num_classes, topk);
+    (*results)[i].scores.resize(topk);
+    for (int j = 0; j < topk; ++j) {
+      (*results)[i].scores[j] = infer_result_data[i * num_classes + (*results)[i].label_ids[j]];
+    }
+  }
+
+  return true;
+}
+
+}  // namespace classification
+}  // namespace vision
+}  // namespace fastdeploy