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import gym
import numpy as np
import torch
from mujoco_py import GlfwContext
from transformers import DecisionTransformerModel
GlfwContext(offscreen=True) # Create a window to init GLFW.
def get_action(model, states, actions, rewards, returns_to_go, timesteps):
# we don't care about the past rewards in this model
states = states.reshape(1, -1, model.config.state_dim)
actions = actions.reshape(1, -1, model.config.act_dim)
returns_to_go = returns_to_go.reshape(1, -1, 1)
timesteps = timesteps.reshape(1, -1)
if model.config.max_length is not None:
states = states[:, -model.config.max_length :]
actions = actions[:, -model.config.max_length :]
returns_to_go = returns_to_go[:, -model.config.max_length :]
timesteps = timesteps[:, -model.config.max_length :]
# pad all tokens to sequence length
attention_mask = torch.cat(
[torch.zeros(model.config.max_length - states.shape[1]), torch.ones(states.shape[1])]
)
attention_mask = attention_mask.to(dtype=torch.long, device=states.device).reshape(1, -1)
states = torch.cat(
[
torch.zeros(
(states.shape[0], model.config.max_length - states.shape[1], model.config.state_dim),
device=states.device,
),
states,
],
dim=1,
).to(dtype=torch.float32)
actions = torch.cat(
[
torch.zeros(
(actions.shape[0], model.config.max_length - actions.shape[1], model.config.act_dim),
device=actions.device,
),
actions,
],
dim=1,
).to(dtype=torch.float32)
returns_to_go = torch.cat(
[
torch.zeros(
(returns_to_go.shape[0], model.config.max_length - returns_to_go.shape[1], 1),
device=returns_to_go.device,
),
returns_to_go,
],
dim=1,
).to(dtype=torch.float32)
timesteps = torch.cat(
[
torch.zeros(
(timesteps.shape[0], model.config.max_length - timesteps.shape[1]), device=timesteps.device
),
timesteps,
],
dim=1,
).to(dtype=torch.long)
else:
attention_mask = None
_, action_preds, _ = model(
states=states,
actions=actions,
rewards=rewards,
returns_to_go=returns_to_go,
timesteps=timesteps,
attention_mask=attention_mask,
return_dict=False,
)
return action_preds[0, -1]
# build the environment
env = gym.make("Hopper-v3")
state_dim = env.observation_space.shape[0]
act_dim = env.action_space.shape[0]
max_ep_len = 1000
device = "cuda"
scale = 1000.0 # normalization for rewards/returns
TARGET_RETURN = 3600 / scale # evaluation conditioning targets, 3600 is reasonable from the paper LINK
state_mean = np.array(
[
1.311279,
-0.08469521,
-0.5382719,
-0.07201576,
0.04932366,
2.1066856,
-0.15017354,
0.00878345,
-0.2848186,
-0.18540096,
-0.28461286,
]
)
state_std = np.array(
[
0.17790751,
0.05444621,
0.21297139,
0.14530419,
0.6124444,
0.85174465,
1.4515252,
0.6751696,
1.536239,
1.6160746,
5.6072536,
]
)
state_mean = torch.from_numpy(state_mean).to(device=device)
state_std = torch.from_numpy(state_std).to(device=device)
# Create the decision transformer model
model = DecisionTransformerModel.from_pretrained("edbeeching/decision-transformer-gym-hopper-medium")
model = model.to(device)
model.eval()
for ep in range(10):
episode_return, episode_length = 0, 0
state = env.reset()
target_return = torch.tensor(TARGET_RETURN, device=device, dtype=torch.float32).reshape(1, 1)
states = torch.from_numpy(state).reshape(1, state_dim).to(device=device, dtype=torch.float32)
actions = torch.zeros((0, act_dim), device=device, dtype=torch.float32)
rewards = torch.zeros(0, device=device, dtype=torch.float32)
timesteps = torch.tensor(0, device=device, dtype=torch.long).reshape(1, 1)
for t in range(max_ep_len):
env.render()
# add padding
actions = torch.cat([actions, torch.zeros((1, act_dim), device=device)], dim=0)
rewards = torch.cat([rewards, torch.zeros(1, device=device)])
action = get_action(
model,
(states.to(dtype=torch.float32) - state_mean) / state_std,
actions.to(dtype=torch.float32),
rewards.to(dtype=torch.float32),
target_return.to(dtype=torch.float32),
timesteps.to(dtype=torch.long),
)
actions[-1] = action
action = action.detach().cpu().numpy()
state, reward, done, _ = env.step(action)
cur_state = torch.from_numpy(state).to(device=device).reshape(1, state_dim)
states = torch.cat([states, cur_state], dim=0)
rewards[-1] = reward
pred_return = target_return[0, -1] - (reward / scale)
target_return = torch.cat([target_return, pred_return.reshape(1, 1)], dim=1)
timesteps = torch.cat([timesteps, torch.ones((1, 1), device=device, dtype=torch.long) * (t + 1)], dim=1)
episode_return += reward
episode_length += 1
if done:
break
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