From 8521c3cff952e9ae5f32ff69580bfdae726afb6f Mon Sep 17 00:00:00 2001
From: Glenn Jocher <glenn.jocher@ultralytics.com>
Date: Mon, 27 Apr 2020 15:22:36 -0700
Subject: [PATCH] cleanup

---
 train.py | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/train.py b/train.py
index ddeda1a7..d32f59e0 100644
--- a/train.py
+++ b/train.py
@@ -249,7 +249,7 @@ def train():
                     if 'momentum' in x:
                         x['momentum'] = np.interp(ni, [0, n_burn], [0.9, hyp['momentum']])
 
-            # Multi-Scale training
+            # Multi-Scale
             if opt.multi_scale:
                 if ni / accumulate % 1 == 0:  #  adjust img_size (67% - 150%) every 1 batch
                     img_size = random.randrange(grid_min, grid_max + 1) * gs
@@ -258,38 +258,36 @@ def train():
                     ns = [math.ceil(x * sf / gs) * gs for x in imgs.shape[2:]]  # new shape (stretched to 32-multiple)
                     imgs = F.interpolate(imgs, size=ns, mode='bilinear', align_corners=False)
 
-            # Run model
+            # Forward
             pred = model(imgs)
 
-            # Compute loss
+            # Loss
             loss, loss_items = compute_loss(pred, targets, model)
             if not torch.isfinite(loss):
                 print('WARNING: non-finite loss, ending training ', loss_items)
                 return results
 
-            # Scale loss by nominal batch_size of 64
-            loss *= batch_size / 64
-
-            # Compute gradient
+            # Backward
+            loss *= batch_size / 64  # scale loss
             if mixed_precision:
                 with amp.scale_loss(loss, optimizer) as scaled_loss:
                     scaled_loss.backward()
             else:
                 loss.backward()
 
-            # Optimize accumulated gradient
+            # Optimize
             if ni % accumulate == 0:
                 optimizer.step()
                 optimizer.zero_grad()
                 ema.update(model)
 
-            # Print batch results
+            # Print
             mloss = (mloss * i + loss_items) / (i + 1)  # update mean losses
             mem = '%.3gG' % (torch.cuda.memory_cached() / 1E9 if torch.cuda.is_available() else 0)  # (GB)
             s = ('%10s' * 2 + '%10.3g' * 6) % ('%g/%g' % (epoch, epochs - 1), mem, *mloss, len(targets), img_size)
             pbar.set_description(s)
 
-            # Plot images with bounding boxes
+            # Plot
             if ni < 1:
                 f = 'train_batch%g.png' % i  # filename
                 plot_images(imgs=imgs, targets=targets, paths=paths, fname=f)