Make Mujoco optional to generate documentation. (#137)

* Remove mandatory import for Mujoco envs. (docs)

* Fix linting and import errors.

* Update changelog.

Author: seba-1511

CHANGELOG.md

@@ -14,6 +14,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+* Mujoco imports optional for docs: the import error is postponed to first method call.
+
 ### Fixed
 
 

learn2learn/gym/envs/mujoco/__init__.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 
+from .dummy_mujoco_env import MujocoEnv
 from .ant_direction import AntDirectionEnv
 from .ant_forward_backward import AntForwardBackwardEnv
 from .halfcheetah_forward_backward import HalfCheetahForwardBackwardEnv

learn2learn/gym/envs/mujoco/ant_direction.py

@@ -2,7 +2,12 @@
 
 import gym
 import numpy as np
-from gym.envs.mujoco.mujoco_env import MujocoEnv
+
+from gym.error import DependencyNotInstalled
+try:
+    from gym.envs.mujoco.mujoco_env import MujocoEnv
+except DependencyNotInstalled:
+    from learn2learn.gym.envs.mujoco.dummy_mujoco_env import MujocoEnv
 
 from learn2learn.gym.envs.meta_env import MetaEnv
 

learn2learn/gym/envs/mujoco/ant_forward_backward.py

@@ -2,7 +2,13 @@
 
 import gym
 import numpy as np
-from gym.envs.mujoco.mujoco_env import MujocoEnv
+
+from gym.error import DependencyNotInstalled
+try:
+    from gym.envs.mujoco.mujoco_env import MujocoEnv
+except DependencyNotInstalled:
+    from learn2learn.gym.envs.mujoco.dummy_mujoco_env import MujocoEnv
+
 
 from learn2learn.gym.envs.meta_env import MetaEnv
 

learn2learn/gym/envs/mujoco/dummy_mujoco_env.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+
+from gym.error import DependencyNotInstalled
+
+
+class MujocoEnv(object):
+    """Dummy class to avoid Mujoco import errors"""
+
+    def __init__(self, model_path=None, frame_skip=None):
+        self.model_path = model_path
+        self.frame_skip = frame_skip
+
+    def _error(self):
+        """docstring for _print_error"""
+        msg = 'Importing MujocoEnv failed. Please run: \n' + \
+              '\n`pip install mujoco-py` \n\n' + \
+              'and visit: ' + \
+              'https://github.com/openai/mujoco-py/'
+        raise DependencyNotInstalled(msg)
+
+    def __hasattr__(self, *args, **kwargs):
+        """docstring for __hasattr__"""
+        self._error()
+
+    def __getattr__(self, *args, **kwargs):
+        """docstring for __getattr__"""
+        self._error()
+
+    def reset(self, *args, **kwargs):
+        """docstring for reset"""
+        self._error()
+
+    def step(self, *args, **kwargs):
+        """docstring for reset"""
+        self._error()
+
+    def seed(self, *args, **kwargs):
+        """docstring for reset"""
+        self._error()

learn2learn/gym/envs/mujoco/halfcheetah_forward_backward.py

@@ -2,7 +2,12 @@
 
 import gym
 import numpy as np
-from gym.envs.mujoco.mujoco_env import MujocoEnv
+
+from gym.error import DependencyNotInstalled
+try:
+    from gym.envs.mujoco.mujoco_env import MujocoEnv
+except DependencyNotInstalled:
+    from learn2learn.gym.envs.mujoco.dummy_mujoco_env import MujocoEnv
 
 from learn2learn.gym.envs.meta_env import MetaEnv
 

learn2learn/gym/envs/mujoco/humanoid_direction.py

@@ -2,7 +2,12 @@
 
 import gym
 import numpy as np
-from gym.envs.mujoco.mujoco_env import MujocoEnv
+
+from gym.error import DependencyNotInstalled
+try:
+    from gym.envs.mujoco.mujoco_env import MujocoEnv
+except DependencyNotInstalled:
+    from learn2learn.gym.envs.mujoco.dummy_mujoco_env import MujocoEnv
 
 from learn2learn.gym.envs.meta_env import MetaEnv
 

learn2learn/gym/envs/mujoco/humanoid_forward_backward.py

@@ -2,7 +2,12 @@
 
 import gym
 import numpy as np
-from gym.envs.mujoco.mujoco_env import MujocoEnv
+
+from gym.error import DependencyNotInstalled
+try:
+    from gym.envs.mujoco.mujoco_env import MujocoEnv
+except DependencyNotInstalled:
+    from learn2learn.gym.envs.mujoco.dummy_mujoco_env import MujocoEnv
 
 from learn2learn.gym.envs.meta_env import MetaEnv