fix vehicle attr doc (#2096)

docs/zh_CN/PULC/PULC_vehicle_attribute.md

@@ -178,7 +178,7 @@ from xml.dom.minidom import parse
 
 vehicleids = []
 
-def convert_annotation(input_fp, output_fp):
+def convert_annotation(input_fp, output_fp, subdir):
     in_file = open(input_fp)
     list_file = open(output_fp, 'w')
     tree = parse(in_file)
@@ -201,12 +201,12 @@ def convert_annotation(input_fp, output_fp):
             typeid = int (item.getAttribute("typeID"))
             label[typeid+9] = '1'
         label = ','.join(label)
-        list_file.write(os.path.join('image_train', name)  + "\t" + label + "\n")
+        list_file.write(os.path.join(subdir, name)  + "\t" + label + "\n")
 
     list_file.close()
 
-convert_annotation('train_label.xml', 'train_list.txt')  #imagename vehiclenum colorid typeid
-convert_annotation('test_label.xml', 'test_list.txt')
+convert_annotation('train_label.xml', 'train_list.txt', 'image_train')  #imagename vehiclenum colorid typeid
+convert_annotation('test_label.xml', 'test_list.txt', 'image_test')
 ```
 
 执行上述命令后，`VeRi`目录中具有以下数据：