add re-ranking code

ppcls/configs/Pedestrian/strong_baseline_baseline.yaml

@@ -12,6 +12,7 @@ Global:
   use_visualdl: False
   eval_mode: "retrieval"
   retrieval_feature_from: "backbone" # 'backbone' or 'neck'
+  re_ranking: False
   # used for static mode and model export
   image_shape: [3, 256, 128]
   save_inference_dir: "./inference"

ppcls/configs/Pedestrian/strong_baseline_m1.yaml

@@ -12,6 +12,7 @@ Global:
   use_visualdl: False
   eval_mode: "retrieval"
   retrieval_feature_from: "features" # 'backbone' or 'features'
+  re_ranking: False
   # used for static mode and model export
   image_shape: [3, 256, 128]
   save_inference_dir: "./inference"

ppcls/configs/Pedestrian/strong_baseline_m1_centerloss.yaml

@@ -12,6 +12,7 @@ Global:
   use_visualdl: False
   eval_mode: "retrieval"
   retrieval_feature_from: "features" # 'backbone' or 'features'
+  re_ranking: False
   # used for static mode and model export
   image_shape: [3, 256, 128]
   save_inference_dir: "./inference"

ppcls/engine/evaluation/retrieval.py

@@ -16,6 +16,9 @@ from __future__ import division
 from __future__ import print_function
 
 import platform
+from typing import Optional
+
+import numpy as np
 import paddle
 from ppcls.utils import logger
 
@@ -48,34 +51,68 @@ def retrieval_eval(engine, epoch_id=0):
     if engine.eval_loss_func is None:
         metric_dict = {metric_key: 0.}
     else:
+        reranking_flag = engine.config['Global'].get('re_ranking', False)
+        logger.info(f"re_ranking={reranking_flag}")
         metric_dict = dict()
-        for block_idx, block_fea in enumerate(fea_blocks):
-            similarity_matrix = paddle.matmul(
-                block_fea, gallery_feas, transpose_y=True)
-            if query_query_id is not None:
-                query_id_block = query_id_blocks[block_idx]
-                query_id_mask = (query_id_block != gallery_unique_id.t())
-
-                image_id_block = image_id_blocks[block_idx]
-                image_id_mask = (image_id_block != gallery_img_id.t())
-
-                keep_mask = paddle.logical_or(query_id_mask, image_id_mask)
-                similarity_matrix = similarity_matrix * keep_mask.astype(
-                    "float32")
-            else:
-                keep_mask = None
-
-            metric_tmp = engine.eval_metric_func(similarity_matrix,
-                                                 image_id_blocks[block_idx],
-                                                 gallery_img_id, keep_mask)
+        if reranking_flag:
+            # set the order from small to large
+            for i in range(len(engine.eval_metric_func.metric_func_list)):
+                if hasattr(engine.eval_metric_func.metric_func_list[i], 'descending') \
+                    and engine.eval_metric_func.metric_func_list[i].descending is True:
+                    engine.eval_metric_func.metric_func_list[
+                        i].descending = False
+                    logger.info(
+                        f"set {engine.eval_metric_func.metric_func_list[i].__class__.__name__}.descending to False when re_ranking=True"
+                    )
+
+            # compute distance matrix(The smaller the value, the more similar)
+            distmat = re_ranking(
+                query_feas, gallery_feas, k1=20, k2=6, lambda_value=0.3)
+            distmat = paddle.to_tensor(distmat)
 
+            # compute keep mask
+            query_id_mask = (query_query_id != gallery_unique_id.t())
+            image_id_mask = (query_img_id != gallery_img_id.t())
+            keep_mask = paddle.logical_or(query_id_mask, image_id_mask)
+
+            # set inf(1e9) distance to those exist in gallery
+            distmat = distmat * keep_mask.astype("float32")
+            inf_mat = (paddle.logical_not(keep_mask).astype("float32")) * 1e20
+            distmat = distmat + inf_mat
+
+            # compute metric
+            metric_tmp = engine.eval_metric_func(distmat, query_img_id,
+                                                 gallery_img_id, keep_mask)
             for key in metric_tmp:
-                if key not in metric_dict:
-                    metric_dict[key] = metric_tmp[key] * block_fea.shape[
-                        0] / len(query_feas)
+                metric_dict[key] = metric_tmp[key]
+        else:
+            for block_idx, block_fea in enumerate(fea_blocks):
+                similarity_matrix = paddle.matmul(
+                    block_fea, gallery_feas, transpose_y=True)  # [n,m]
+                if query_query_id is not None:
+                    query_id_block = query_id_blocks[block_idx]
+                    query_id_mask = (query_id_block != gallery_unique_id.t())
+
+                    image_id_block = image_id_blocks[block_idx]
+                    image_id_mask = (image_id_block != gallery_img_id.t())
+
+                    keep_mask = paddle.logical_or(query_id_mask, image_id_mask)
+                    similarity_matrix = similarity_matrix * keep_mask.astype(
+                        "float32")
                 else:
-                    metric_dict[key] += metric_tmp[key] * block_fea.shape[
-                        0] / len(query_feas)
+                    keep_mask = None
+
+                metric_tmp = engine.eval_metric_func(
+                    similarity_matrix, image_id_blocks[block_idx],
+                    gallery_img_id, keep_mask)
+
+                for key in metric_tmp:
+                    if key not in metric_dict:
+                        metric_dict[key] = metric_tmp[key] * block_fea.shape[
+                            0] / len(query_feas)
+                    else:
+                        metric_dict[key] += metric_tmp[key] * block_fea.shape[
+                            0] / len(query_feas)
 
     metric_info_list = []
     for key in metric_dict:
@@ -185,3 +222,109 @@ def cal_feature(engine, name='gallery'):
     logger.info("Build {} done, all feat shape: {}, begin to eval..".format(
         name, all_feas.shape))
     return all_feas, all_img_id, all_unique_id
+
+
+def re_ranking(query_feas: paddle.Tensor,
+               gallery_feas: paddle.Tensor,
+               k1: int=20,
+               k2: int=6,
+               lambda_value: int=0.5,
+               local_distmat: Optional[np.ndarray]=None,
+               only_local: bool=False) -> paddle.Tensor:
+    """re-ranking, most computed with numpy
+
+    code heavily based on
+    https://github.com/michuanhaohao/reid-strong-baseline/blob/3da7e6f03164a92e696cb6da059b1cd771b0346d/utils/reid_metric.py
+
+    Args:
+        query_feas (paddle.Tensor): query features, [num_query, num_features]
+        gallery_feas (paddle.Tensor): gallery features, [num_gallery, num_features]
+        k1 (int, optional): k1. Defaults to 20.
+        k2 (int, optional): k2. Defaults to 6.
+        lambda_value (int, optional): lambda. Defaults to 0.5.
+        local_distmat (Optional[np.ndarray], optional): local_distmat. Defaults to None.
+        only_local (bool, optional): only_local. Defaults to False.
+
+    Returns:
+        paddle.Tensor: final_dist matrix after re-ranking, [num_query, num_gallery]
+    """
+    query_num = query_feas.shape[0]
+    all_num = query_num + gallery_feas.shape[0]
+    if only_local:
+        original_dist = local_distmat
+    else:
+        feat = paddle.concat([query_feas, gallery_feas])
+        logger.info('using GPU to compute original distance')
+
+        # L2 distance
+        distmat = paddle.pow(feat, 2).sum(axis=1, keepdim=True).expand([all_num, all_num]) + \
+            paddle.pow(feat, 2).sum(axis=1, keepdim=True).expand([all_num, all_num]).t()
+        distmat = distmat.addmm(x=feat, y=feat.t(), alpha=-2.0, beta=1.0)
+
+        original_dist = distmat.cpu().numpy()
+        del feat
+        if local_distmat is not None:
+            original_dist = original_dist + local_distmat
+
+    gallery_num = original_dist.shape[0]
+    original_dist = np.transpose(original_dist / np.max(original_dist, axis=0))
+    V = np.zeros_like(original_dist).astype(np.float16)
+    initial_rank = np.argsort(original_dist).astype(np.int32)
+    logger.info('starting re_ranking')
+    for i in range(all_num):
+        # k-reciprocal neighbors
+        forward_k_neigh_index = initial_rank[i, :k1 + 1]
+        backward_k_neigh_index = initial_rank[forward_k_neigh_index, :k1 + 1]
+        fi = np.where(backward_k_neigh_index == i)[0]
+        k_reciprocal_index = forward_k_neigh_index[fi]
+        k_reciprocal_expansion_index = k_reciprocal_index
+        for j in range(len(k_reciprocal_index)):
+            candidate = k_reciprocal_index[j]
+            candidate_forward_k_neigh_index = initial_rank[candidate, :int(
+                np.around(k1 / 2)) + 1]
+            candidate_backward_k_neigh_index = initial_rank[
+                candidate_forward_k_neigh_index, :int(np.around(k1 / 2)) + 1]
+            fi_candidate = np.where(
+                candidate_backward_k_neigh_index == candidate)[0]
+            candidate_k_reciprocal_index = candidate_forward_k_neigh_index[
+                fi_candidate]
+            if len(
+                    np.intersect1d(candidate_k_reciprocal_index,
+                                   k_reciprocal_index)) > 2 / 3 * len(
+                                       candidate_k_reciprocal_index):
+                k_reciprocal_expansion_index = np.append(
+                    k_reciprocal_expansion_index, candidate_k_reciprocal_index)
+
+        k_reciprocal_expansion_index = np.unique(k_reciprocal_expansion_index)
+        weight = np.exp(-original_dist[i, k_reciprocal_expansion_index])
+        V[i, k_reciprocal_expansion_index] = weight / np.sum(weight)
+    original_dist = original_dist[:query_num, ]
+    if k2 != 1:
+        V_qe = np.zeros_like(V, dtype=np.float16)
+        for i in range(all_num):
+            V_qe[i, :] = np.mean(V[initial_rank[i, :k2], :], axis=0)
+        V = V_qe
+        del V_qe
+    del initial_rank
+    invIndex = []
+    for i in range(gallery_num):
+        invIndex.append(np.where(V[:, i] != 0)[0])
+
+    jaccard_dist = np.zeros_like(original_dist, dtype=np.float16)
+    for i in range(query_num):
+        temp_min = np.zeros(shape=[1, gallery_num], dtype=np.float16)
+        indNonZero = np.where(V[i, :] != 0)[0]
+        indImages = [invIndex[ind] for ind in indNonZero]
+        for j in range(len(indNonZero)):
+            temp_min[0, indImages[j]] = temp_min[0, indImages[j]] + np.minimum(
+                V[i, indNonZero[j]], V[indImages[j], indNonZero[j]])
+        jaccard_dist[i] = 1 - temp_min / (2 - temp_min)
+
+    final_dist = jaccard_dist * (1 - lambda_value
+                                 ) + original_dist * lambda_value
+    del original_dist
+    del V
+    del jaccard_dist
+    final_dist = final_dist[:query_num, query_num:]
+    final_dist = paddle.to_tensor(final_dist)
+    return final_dist

ppcls/metric/metrics.py

@@ -43,15 +43,16 @@ class TopkAcc(nn.Layer):
 
 
 class mAP(nn.Layer):
-    def __init__(self):
+    def __init__(self, descending=True):
         super().__init__()
+        self.descending = descending
 
     def forward(self, similarities_matrix, query_img_id, gallery_img_id,
                 keep_mask):
         metric_dict = dict()
 
         choosen_indices = paddle.argsort(
-            similarities_matrix, axis=1, descending=True)
+            similarities_matrix, axis=1, descending=self.descending)
         gallery_labels_transpose = paddle.transpose(gallery_img_id, [1, 0])
         gallery_labels_transpose = paddle.broadcast_to(
             gallery_labels_transpose,
@@ -87,15 +88,16 @@ class mAP(nn.Layer):
 
 
 class mINP(nn.Layer):
-    def __init__(self):
+    def __init__(self, descending=True):
         super().__init__()
+        self.descending = descending
 
     def forward(self, similarities_matrix, query_img_id, gallery_img_id,
                 keep_mask):
         metric_dict = dict()
 
         choosen_indices = paddle.argsort(
-            similarities_matrix, axis=1, descending=True)
+            similarities_matrix, axis=1, descending=self.descending)
         gallery_labels_transpose = paddle.transpose(gallery_img_id, [1, 0])
         gallery_labels_transpose = paddle.broadcast_to(
             gallery_labels_transpose,
@@ -130,12 +132,13 @@ class mINP(nn.Layer):
 
 
 class Recallk(nn.Layer):
-    def __init__(self, topk=(1, 5)):
+    def __init__(self, topk=(1, 5), descending=True):
         super().__init__()
         assert isinstance(topk, (int, list, tuple))
         if isinstance(topk, int):
             topk = [topk]
         self.topk = topk
+        self.descending = descending
 
     def forward(self, similarities_matrix, query_img_id, gallery_img_id,
                 keep_mask):
@@ -143,7 +146,7 @@ class Recallk(nn.Layer):
 
         #get cmc
         choosen_indices = paddle.argsort(
-            similarities_matrix, axis=1, descending=True)
+            similarities_matrix, axis=1, descending=self.descending)
         gallery_labels_transpose = paddle.transpose(gallery_img_id, [1, 0])
         gallery_labels_transpose = paddle.broadcast_to(
             gallery_labels_transpose,
@@ -175,12 +178,13 @@ class Recallk(nn.Layer):
 
 
 class Precisionk(nn.Layer):
-    def __init__(self, topk=(1, 5)):
+    def __init__(self, topk=(1, 5), descending=True):
         super().__init__()
         assert isinstance(topk, (int, list, tuple))
         if isinstance(topk, int):
             topk = [topk]
         self.topk = topk
+        self.descending = descending
 
     def forward(self, similarities_matrix, query_img_id, gallery_img_id,
                 keep_mask):
@@ -188,7 +192,7 @@ class Precisionk(nn.Layer):
 
         #get cmc
         choosen_indices = paddle.argsort(
-            similarities_matrix, axis=1, descending=True)
+            similarities_matrix, axis=1, descending=self.descending)
         gallery_labels_transpose = paddle.transpose(gallery_img_id, [1, 0])
         gallery_labels_transpose = paddle.broadcast_to(
             gallery_labels_transpose,