Update dataset_traversal.py
diff --git a/ppocr/data/rec/dataset_traversal.py b/ppocr/data/rec/dataset_traversal.py
index 5efba512c0..ebee624ab7 100755
--- a/ppocr/data/rec/dataset_traversal.py
+++ b/ppocr/data/rec/dataset_traversal.py
@@ -237,7 +237,7 @@ def __call__(self, process_id):
 
         def get_device_num():
             if self.use_gpu:
-                gpus = os.environ.get("CUDA_VISIBLE_DEVICES", 1)
+                gpus = os.environ.get("CUDA_VISIBLE_DEVICES", '1')
                 gpu_num = len(gpus.split(','))
                 return gpu_num
             else:

CUDA_VISIBLE_DEVICES 默认值必须为str, 否则split会报错