How to access instance token given sample token?

Given the sample token, how do I access instance token for the ego-vehicle?
It seems to be easy to access the instance token for each object present in the scene (using the helper.get_annotations_for_sample(sample_token) API), but I couldn’t find a way to access an instance token specifically for the ego-vehicle.

The “instance” of the ego is simply the sample itself, which you easily access as follows:

my_sample = nusc.get('sample', some_sample_token)

Do check out our tutorial for more details:

So are you saying that my_sample['token'] in the snippet above will give me the instance token?

It does not seem to be correct though. What I want to be able to do is to cross-reference the samples between the full nuScenes dataset and the prediction challenge split.

If what you are saying is true, then the following code must pass correct?

self.nuscenes = NuScenes(dataset_ver, dataroot=root_path)
self.nuscenes_challenge_split = get_prediction_challenge_split("train", dataroot=root_path)

# get a reference instance and sample token
ref_instance_token, ref_sample_token = self.nuscenes_challenge_split[0].split("_")

# go through each sample
for scene in self.nuscenes.scene:
    sample_token = scene['first_sample_token']
    while sample_token != '':
        sample = self.nuscenes.get('sample', sample_token)
        if sample_token == ref_sample_token:
            assert sample['token'] == ref_instance_token