fix infer class_num bugs in release/2.0-beta branch

tools/infer/infer.py

@@ -39,6 +39,7 @@ def parse_args():
     parser.add_argument("-m", "--model", type=str)
     parser.add_argument("-p", "--pretrained_model", type=str)
     parser.add_argument("--use_gpu", type=str2bool, default=True)
+    parser.add_argument("--class_num", type=int, default=1000)
     parser.add_argument(
         "--load_static_weights",
         type=str2bool,
@@ -122,7 +123,7 @@ def main():
 
     paddle.disable_static(place)
 
-    net = architectures.__dict__[args.model]()
+    net = architectures.__dict__[args.model](class_dim=args.class_num)
     load_dygraph_pretrain(net, args.pretrained_model, args.load_static_weights)
     image_list = get_image_list(args.image_file)
     for idx, filename in enumerate(image_list):