Update test.py --task speed and study (#2099)

* Add --speed benchmark

* test range 256 - 1536

* update

* update

* update

* update

test.py

              save_conf=opt.save_conf,
              )
 
+    elif opt.task == 'speed':  # speed benchmarks
+        for w in opt.weights:
+            test(opt.data, w, opt.batch_size, opt.img_size, 0.25, 0.45, save_json=False, plots=False)
+
     elif opt.task == 'study':  # run over a range of settings and save/plot
-        for weights in ['yolov5s.pt', 'yolov5m.pt', 'yolov5l.pt', 'yolov5x.pt']:
-            f = 'study_%s_%s.txt' % (Path(opt.data).stem, Path(weights).stem)  # filename to save to
-            x = list(range(320, 800, 64))  # x axis
+        x = list(range(256, 1536 + 128, 128))  # x axis (image sizes)
+        for w in opt.weights:
+            f = f'study_{Path(opt.data).stem}_{Path(w).stem}.txt'  # filename to save to
             y = []  # y axis
             for i in x:  # img-size
-                print('\nRunning %s point %s...' % (f, i))
-                r, _, t = test(opt.data, weights, opt.batch_size, i, opt.conf_thres, opt.iou_thres, opt.save_json,
+                print(f'\nRunning {f} point {i}...')
+                r, _, t = test(opt.data, w, opt.batch_size, i, opt.conf_thres, opt.iou_thres, opt.save_json,
                                plots=False)
                 y.append(r + t)  # results and times
             np.savetxt(f, y, fmt='%10.4g')  # save
         os.system('zip -r study.zip study_*.txt')
-        plot_study_txt(f, x)  # plot
+        plot_study_txt(x=x)  # plot

utils/plots.py

     plt.savefig('targets.jpg', dpi=200)
 
 
-def plot_study_txt(path='study/', x=None):  # from utils.plots import *; plot_study_txt()
+def plot_study_txt(path='', x=None):  # from utils.plots import *; plot_study_txt()
     # Plot study.txt generated by test.py
     fig, ax = plt.subplots(2, 4, figsize=(10, 6), tight_layout=True)
     ax = ax.ravel()