Update `feature_visualization()` (#3807)

* Update `feature_visualization()`

Only plot for data with height, width > 1

* cleanup

* Cleanup

utils/plots.py

@@ -448,26 +448,28 @@ def plot_results(start=0, stop=0, bucket='', id=(), labels=(), save_dir=''):
     fig.savefig(Path(save_dir) / 'results.png', dpi=200)
 
 
-def feature_visualization(features, module_type, module_idx, n=64):
+def feature_visualization(x, module_type, stage, n=64):
     """
-    features:       Features to be visualized
+    x:              Features to be visualized
     module_type:    Module type
-    module_idx:     Module layer index within model
+    stage:          Module stage within model
     n:              Maximum number of feature maps to plot
     """
-    project, name = 'runs/features', 'exp'
-    save_dir = increment_path(Path(project) / name)  # increment run
-    save_dir.mkdir(parents=True, exist_ok=True)  # make dir
-
-    plt.figure(tight_layout=True)
-    blocks = torch.chunk(features, features.shape[1], dim=1)  # block by channel dimension
-    n = min(n, len(blocks))
-    for i in range(n):
-        feature = transforms.ToPILImage()(blocks[i].squeeze())
-        ax = plt.subplot(int(math.sqrt(n)), int(math.sqrt(n)), i + 1)
-        ax.axis('off')
-        plt.imshow(feature)  # cmap='gray'
-
-    f = f"layer_{module_idx}_{module_type.split('.')[-1]}_features.png"
-    print(f'Saving {save_dir / f}...')
-    plt.savefig(save_dir / f, dpi=300)
+    batch, channels, height, width = x.shape  # batch, channels, height, width
+    if height > 1 and width > 1:
+        project, name = 'runs/features', 'exp'
+        save_dir = increment_path(Path(project) / name)  # increment run
+        save_dir.mkdir(parents=True, exist_ok=True)  # make dir
+
+        plt.figure(tight_layout=True)
+        blocks = torch.chunk(x, channels, dim=1)  # block by channel dimension
+        n = min(n, len(blocks))
+        for i in range(n):
+            feature = transforms.ToPILImage()(blocks[i].squeeze())
+            ax = plt.subplot(int(math.sqrt(n)), int(math.sqrt(n)), i + 1)
+            ax.axis('off')
+            plt.imshow(feature)  # cmap='gray'
+
+        f = f"stage_{stage}_{module_type.split('.')[-1]}_features.png"
+        print(f'Saving {save_dir / f}...')
+        plt.savefig(save_dir / f, dpi=300)