Formating python json dump

Question

I am writing a python script that will parse through a directory of over 100 images and dump the information into a JSON file. The script is able to properly update and append data, but I want to improve the formmating. I want it to be compact like this:

{
    "list_example" : [1, 2, 3, 4, 5, 6, 7, 8, 9],
    "dict_example": {
        "index1": {
            "image_label_1": "image_file_path_1"
        },
        "index2": {
            "image_label_2": "image_file_path_2"
        }
    }
}

The current JSON file looks like this:

{
   "list_example": [
      1,
      2,
      3,
      4,
      5,
      6,
      7,
      8,
      9
   ],
   "dict_example": {
      "index": {
         "label": "image_file_path_1"
      },
      "index2": {
         "label2": "image_file_path_2"
      }
   }
}

I am struggling to find a way to keep the array contained in one line while having the dictionaries on separate lines. This is the current code I am using to dump the data:

# Write to json file
with open('dataset.json','w') as outfile:
    json.dump(example_data, outfile, indent=3)