[proposal] Public `VecNormalize._normalize_observation`

I have saved demonstrations from a particular environment, and also a PPO2 policy trained on a normalized version of the same environment.

To properly compare the unnormalized observations in the demonstration against the PPO2 policy I am using VecNormalize._normalize_observation(obs_demo). For ease of use, I’m wondering if the maintainers would be fine with:

1. Rename _normalize_obs to normalize_obs so that it is a “public” method.
2. Add training param to normalize_obs() so that we can call the normalize_obs without changing normalizing statistics. VecNormalize.step() would call self.normalize_obs(obs, training=self.training).

[araffin]

Good point, i think this is also a good moment to rename rew to reward

@araffin Did you mean that you want to rename self.get_original_{rew=>rewards}? (If so I will also self.get_original_{obs=>observations}

only the first one (the 2nd one would break some code and is maybe too long), and it would be singular i think (but it does not really matter)

[araffin]

Good point, i think this is also a good moment to rename rew to reward