fix predict dim (#1739)

Co-authored-by: Weisu Yin <[email protected]>

gluoncv/auto/estimators/torch_image_classification/torch_image_classification.py

@@ -673,12 +673,13 @@ def _predict(self, x, **kwargs):
             return pd.DataFrame(results)
         elif not isinstance(x, torch.Tensor):
             raise ValueError('Input is not supported: {}'.format(type(x)))
+        assert len(x.shape) == 4 and x.shape[1] == 3, f"Expect input to be (n, 3, h, w), given {x.shape}"
         with torch.no_grad():
             input = x.to(self.ctx[0])
             label = self.net(input)
             if self._problem_type in [MULTICLASS, BINARY]:
                 topk = min(5, self.num_class)
-                probs = nn.functional.softmax(label, dim=0).cpu().numpy().flatten()
+                probs = nn.functional.softmax(label, dim=1).cpu().numpy().flatten()
                 topk_inds = label.topk(topk)[1].cpu().numpy().flatten()
                 if with_proba:
                     df = pd.DataFrame([{'image_proba': probs.tolist()}])