Issue: vmapped CartPole input shape does not match

[Dries Smit]

Hello there. I am trying to run a vmapped CartPole step function. My environment state inputs are of the shape:

env_state:
[executor/0] x:  Traced<ShapedArray(float32[])>with<DynamicJaxprTrace(level=2/0)>
[executor/0] x_dot:  Traced<ShapedArray(float32[])>with<DynamicJaxprTrace(level=2/0)>
[executor/0] theta:  Traced<ShapedArray(float32[])>with<DynamicJaxprTrace(level=2/0)>
[executor/0] theta_dot:  Traced<ShapedArray(float32[])>with<DynamicJaxprTrace(level=2/0)>

When I run jnp.array([env_state.x, env_state.x_dot, env_state.theta, env_state.theta_dot]) on the state, before the environment step, and get out:
Traced<ShapedArray(float32[4])>with<DynamicJaxprTrace(level=2/0)>

However when I try to run the step function I get:

obs, env_state, rewards, done, _ = self.env.step(key_step, env_state, action, self.env_params)
[executor/0]   File "/mava/lib/python3.8/site-packages/gymnax/environments/environment.py", line 38, in step
[executor/0]     obs_st, state_st, reward, done, info = self.step_env(
[executor/0]   File "/mava/lib/python3.8/site-packages/gymnax/environments/classic_control/cartpole.py", line 83, in step_env
[executor/0]     lax.stop_gradient(self.get_obs(state)),
[executor/0]   File "/mava/lib/python3.8/site-packages/gymnax/environments/classic_control/cartpole.py", line 108, in get_obs
[executor/0]     return jnp.array([state.x, state.x_dot, state.theta, state.theta_dot])
[executor/0]   File "/mava/lib/python3.8/site-packages/jax/_src/numpy/lax_numpy.py", line 1889, in array
[executor/0]     out = stack([asarray(elt, dtype=dtype) for elt in object])
[executor/0]   File "/mava/lib/python3.8/site-packages/jax/_src/numpy/lax_numpy.py", line 1634, in stack
[executor/0]     raise ValueError("All input arrays must have the same shape.")
[executor/0] ValueError: All input arrays must have the same shape.

Do you have any idea what might be causing this issue? Is the shapes somehow changing inside the step function? Thanks.

[Dries Smit]

Apologies, it was not to do with the environment. It was because I was passing an action logit array of size 2 to the environment.