解释for c in det[:, -1].unique(): n = (det[:, -1] == c).sum() s += '%g %ss, ' % (n, names[int(c)])

这段代码是对于一个二维数组det，其中[:, -1]表示取det数组的最后一列，.unique()函数表示取该列的不同值，即去重后的结果。for循环遍历这些不同的值，对于每个值c，统计该值在该列中出现的次数n，然后将次数n与对应的名称（names[int(c)]）拼接成一个字符串，格式为'%g %ss, ' % (n, names[int(c)])，其中%g是格式化浮点数，%ss是格式化字符串，%后面的括号中是对应的变量。最后将所有字符串拼接成一个长字符串s返回。

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代码解释 if len(det): # Rescale boxes from img_size to im0 size det[:, :4] = scale_coords(img.shape[2:], det[:, :4], im0.shape).round() # Print results for c in det[:, -1].unique(): n = (det[:, -1] == c).sum() # detections per class s += f"{n} {names[int(c)]}{'s' * (n > 1)}, " # add to string # Write results for *xyxy, conf, cls in reversed(det): if save_txt: # Write to file xywh = (xyxy2xywh(torch.tensor(xyxy).view(1, 4)) / gn).view(-1).tolist() # normalized xywh line = (cls, *xywh, conf) if opt.save_conf else (cls, *xywh) # label format with open(txt_path + '.txt', 'a') as f: f.write(('%g ' * len(line)).rstrip() % line + '\n') if save_img or view_img: # Add bbox to image label = f'{names[int(cls)]} {conf:.2f}' plot_one_box(xyxy, im0, label=label, color=colors[int(cls)], line_thickness=1)

这段代码是用来处理检测结果的。首先，它会判断检测结果列表(det)是否非空，如果非空则进行结果处理。接着，将检测框从img_size大小重新缩放到im0大小，并将结果输出到字符串s中。之后，对于每一个检测框，如果save_txt为True，则将其保存到txt文件中；如果save_img或者view_img为True，则将检测框画在图像上。最后，输出的结果包括检测框的类别、位置和置信度。

代码解释# Process detections for i, det in enumerate(pred): # detections per image if webcam: # batch_size >= 1 p, s, im0 = path[i], '%g: ' % i, im0s[i].copy() else: p, s, im0 = path, '', im0s save_path = str(Path(out) / Path(p).name) s += '%gx%g ' % img.shape[2:] # print string gn = torch.tensor(im0.shape)[[1, 0, 1, 0]] # normalization gain whwh if det is not None and len(det): # Rescale boxes from img_size to im0 size det[:, :4] = scale_coords(img.shape[2:], det[:, :4], im0.shape).round() # Print results for c in det[:, -1].unique(): n = (det[:, -1] == c).sum() # detections per class s += '%g %ss, ' % (n, names[int(c)]) # add to string # Write results for *xyxy, conf, cls in det: if save_txt: # Write to file xywh = (xyxy2xywh(torch.tensor(xyxy).view(1, 4)) / gn).view(-1).tolist() # normalized xywh with open(save_path[:save_path.rfind('.')] + '.txt', 'a') as file: file.write(('%g ' * 5 + '\n') % (cls, *xywh)) # label format if save_img or view_img: # Add bbox to image label = '%s %.2f' % (names[int(cls)], conf) if label is not None: if (label.split())[0] == 'person': people_coords.append(xyxy) # plot_one_box(xyxy, im0, line_thickness=3) plot_dots_on_people(xyxy, im0) # Plot lines connecting people distancing(people_coords, im0, dist_thres_lim=(100, 150)) # Print time (inference + NMS) print('%sDone. (%.3fs)' % (s, t2 - t1)) # Stream results if 1: ui.showimg(im0) if cv2.waitKey(1) == ord('q'): # q to quit raise StopIteration # Save results (image with detections) if save_img: if dataset.mode == 'images': cv2.imwrite(save_path, im0) else: if vid_path != save_path: # new video vid_path = save_path if isinstance(vid_writer, cv2.VideoWriter): vid_writer.release() # release previous video writer fps = vid_cap.get(cv2.CAP_PROP_FPS) w = int(vid_cap.get(cv2.CAP_PROP_FRAME_WIDTH)) h = int(vid_cap.get(cv2.CAP_PROP_FRAME_HEIGHT)) vid_writer = cv2.VideoWriter(save_path, cv2.VideoWriter_fourcc(*opt.fourcc), fps, (w, h)) vid_writer.write(im0)

这段代码是目标检测算法的输出结果处理部分。主要包括以下几个步骤：

1. 对每张图片的检测结果进行处理，包括将检测框从输入图像的尺寸缩放到输出图像的尺寸，并将结果写入文本文件中。

2. 对每个类别的检测结果统计数量，并将数量和类别名称添加到输出字符串中。

3. 对每个检测到的目标绘制边界框，并在边界框上标注类别和置信度。

4. 如果检测到的目标是人，则将其坐标保存在列表中，并在图像上绘制点和连线进行社交距离监测。

5. 将处理后的图像展示出来，并将图像保存到文件中。