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+Comparisons with other Frameworks
+=================================
+
+Frameworks can mostly be divided into 2 groups:
+
+1. the ones that focus on providing environments
+2. the ones that focus on providing learning models and algorithms
+
+In this document, I will review and compare the various frameworks.
+
+PyRoboLearn:
+
+* OS: Ubuntu 16.04 and 18.04. Also, Windows 10, and Mac OSX but does not support all interfaces.
+* Python: 2.7, 3.5, 3.6
+* PEP8 compliant (unified code style)
+* Documented functions and classes
+* Unified framework
+
+
+Simulators
+----------
+
+In this section, we first review the various robotic simulators, and provide comparisons between them:
+
+* Gazebo-ROS
+    * free + open source
+    * C++ (Python through ROS)
+    * Python 3.* but Python 2.7 for some ROS packages
+    * `Gazebo <http://gazebosim.org/>`__, `ROS <https://www.ros.org/>`__
+* Bullet/PyBullet
+    * Free (zlib license) + open source
+    * C++
+    * Python wrapper (Python 2.7 and 3.*)
+    * `Bullet Github repo <https://github.com/bulletphysics/bullet3>`__, and
+      `Pybullet Github repo <https://github.com/bulletphysics/bullet3/tree/master/examples/pybullet>`__
+* Mujoco/mujoco-py
+    * Not free unless student but cannot be used for research (require a License) + not open-source
+    * C
+    * Python wrapper (Python 3.5)
+    * `Main Webpage <http://www.mujoco.org/>`__, `mujoco-py <https://github.com/openai/mujoco-py>`__
+* Dart
+    * free + open-source
+    * C++
+    * Python wrapper (dartpy)
+    * `Main Webpage <https://dartsim.github.io/>`__
+* RaiSim/RaiSimPy
+    * free + not open-source (the cpp files)
+    * C++
+    * Python wrapper (Python 2.7 and 3.*)
+    * `RaiSimLib <https://github.com/leggedrobotics/raisimLib>`__,
+      `RaiSim Ogre <https://github.com/leggedrobotics/raisimOgre>`__,
+      `RaiSimPy <https://github.com/robotlearn/raisimpy>`__
+* V-REP/PyRep
+    * free + open-source
+    * C++
+    * Python wrapper (Python 3.*)
+    * `V-REP <http://www.coppeliarobotics.com/>`__, `PyRep <https://github.com/stepjam/PyRep>`__
+* Isaac Gym (PhysX and FleX)
+    * not available for now
+    * C++
+* Webots
+    * free + open-source
+    * C++
+    * No Python wrappers
+    * `Main webpage <https://cyberbotics.com/>`__, `Github repo <https://github.com/cyberbotics/webots>`__
+* Argos3
+    * free + open-source
+    * C++
+    * Purpose: for multiple robots
+    * No Python wrappers
+    * `Main webpage <https://www.argos-sim.info/>`__, `Github repo <https://github.com/ilpincy/argos3>`__
+* Chronos/PyChronos
+    * free + open-source + cross-platform (BSD-3 license)
+    * C++
+    * `Chronos <https://projectchrono.org/>`__, `PyChronos <https://projectchrono.org/pychrono/>`__
+* OpenSim
+    * Purpose: "to develop models of musculoskeletal structures and create dynamic simulations of movement"
+    * OS: Linux, Windows, Ubuntu
+    * C++
+    * `Main Webpage <https://opensim.stanford.edu/>`__,
+      `Documentation <https://simtk-confluence.stanford.edu:8443/display/OpenSim/OpenSim+Documentation>`__,
+      `Github repo <https://github.com/opensim-org/opensim-core>`__
+* Airsim
+    * Purpose: simulator for mainly drones and cars
+    * Backend: Unreal Engine
+    * C++
+    * Python client
+    * `Documentation <https://microsoft.github.io/AirSim/>`__, `Github repo <https://github.com/microsoft/AirSim>`__
+* Carla
+    * Purpose: simulator for autonomous driving systems
+    * C++
+    * Python client
+    * `Main webpage <http://carla.org/>`__, `Documentation <https://carla.readthedocs.io/en/stable/>`__
+
+Not really simulators but more like tools:
+
+* Drake
+    * modelling dynamical systems + solving mathematical programs + multibody kinematics and dynamics
+    * C++
+    * Python wrapper
+    * `Main Webpage <https://drake.mit.edu/>`__
+* Robotics toolbox
+    * Matlab
+    * No Python wrappers
+    * `Main Webpage <http://petercorke.com/wordpress/toolboxes/robotics-toolbox>`__
+
+Not really simulators but provide physics engine (i.e. dynamics/physics library):
+
+* ODE
+    * C++
+    * `Bitbucket repo <https://bitbucket.org/odedevs/ode>`__
+* SimBody
+    * C++
+    * `Main Webpage <https://simtk.org/projects/simbody>`__, `Github repo <https://github.com/simbody/simbody>`__
+
+
+The following table summarizes the comparisons between the various simulators:
+
+.. csv-table::
+    :header: "Name", "Language", "Free", "Open-source", "Supported OS", "Python wrapper", "Main purpose", "License"
+
+    "Bullet", "C/C++", "Yes", "Yes", "Linux, Mac OSX, Windows", "2.7 and 3.*", "Robotics, Game, Graphics", "Zlib"
+    "MuJoCo", "C", "Yes", "No", "Linux, Mac OSX, Windows", "mujoco_py >=3.5", "Robotics, Game, Graphics", "Proprietary (MIT for mujoco_py)"
+    "Dart", "C++", "Yes", "Yes", "Linux, Mac OSX, Windows", "2.7 and 3.*", "Robotics", "BSD 2"
+    "Raisim", "C++", "Yes", "No", "Linux (Ubuntu)", "2.7 and 3.*", "Robotics", "EULA (MIT for raisimpy)"
+    "V-Rep", "C++", "Yes", "Yes", "Linux (Ubuntu), Mac OSX, Windows", ">= 3.5", "Robotics", "Commercial or GNU GPL (MIT for PyRep)"
+    "Gazebo + ROS", "C++", "Yes", "Yes", "NA", "ROS (2.7 and some packages >=3.5)", "Robotics", "Apache 2.0 (for Gazebo), BSD3 (for ROS)"
+    "Isaac", "C++", "NA", "NA", "NA", "NA", "Robotics", "NA"
+    "Chronos", "C++", "Yes", "Yes", "Linux, Mac OSX, Windows", "Yes", "Robotics", "BSD3"
+    "OpenSim", "C++", "Yes", "Yes", "Mac OSX, Windows", "NA", "Musculoskeletal models", "Apache 2.0"
+    "Airsim", "C++", "Yes", "Yes", "Linux and Windows", ">=3.5", "Cars and Drones", "MIT"
+    "Carla", "C++", "Yes", "Yes", "Linux and Windows", "Yes", "Autonomous driving agents", "MIT"
+    "Webots", "C++", "Yes", "Yes", "Linux, Mac OSX, Windows", "No", "Robotics", "Apache 2.0"
+    "Argos3", "C++", "Yes", "Yes", "Linux, Mac OSX", "No", "Swarm Robotics", "MIT"
+
+
+Have also a look at `SimBenchmark <https://leggedrobotics.github.io/SimBenchmark/>`__ for a comparison between various
+physics engines.
+
+
+Environments
+------------
+
+* OpenAI Gym
+    * OS: Linux and OS X
+    * Python 2.7 or 3.5
+* gym-miniworld
+    * Python 3.5+
+* DeepMind Control Suite
+    * OS: Ubuntu 14.04 and 16.04
+    * Python: 2.7 and 3.5
+    * Simulator: Mujoco
+* Roboschool
+    * OS: Ubuntu/Debian and Mac OS X
+    * Python 3 (might be compatible with Python 2.7 but "may require non-trivial amount of work")
+    * Simulator: Internal
+* Pybullet Gym
+    * OS: Linux, Windows and OS X
+    * Python 2.7 or 3.5
+    * Simulator: PyBullet
+* GibsonEnv
+    * Nvidia GPU with VRAM > 6GB
+    * OS: Ubuntu >= 14.04
+    * Python 3.5 is recommended
+* AI-habitat
+    * Python 3
+* Airsim
+    * Requirements:
+        * OS: Linux and Windows
+        * C++, Python, C# and Java
+        * Unreal Engine + Unity
+* Carla
+    * OS: Linux and Windows
+    * Python
+* Nvidia Isaac Gym/Sim
+    * Information unavailable for the moment
+* Surreal Robotics Suite
+    * OS: Mac OS X and Linux
+    * Python 3.5 or 3.7
+    * Simulator: Mujoco
+    * Robots: Baxter
+    * Devices: mouse and spacemouse
+    * Paradigms: Imitation and reinforcement
+    * Robot Manipulation
+* PyRobot
+    * OS: Ubuntu 16.04
+    * Python 2.7
+    * Simulator: Gazebo(+ROS)
+    * PyRobot is a lightweight Python framework which is built on top of Gazebo-ROS, and focuses on manipulation and navigation.
+    * Comparisons with PyRoboLearn: PyRoboLearn can be seen as the more heavyweight version of that framework.
+* S-RL Toolbox (Reinforcement Learning (RL) and State Representation Learning (SRL) Toolbox for Robotics)
+    * OS: Linux, Mac OSX, Windows
+    * Python 3
+    * Simulator: PyBullet
+    * use stable-baselines
+* RLBench
+    * OS: Ubuntu 16.04 + Windows + Mac OSX
+    * Python 3
+    * Simulator: PyRep
+    * Paradigms: 
+    * https://github.com/stepjam/RLBench
+* gym-chrono
+    * OS: Linux, Windows, OSX
+    * Python
+    * Simulator: PyChrono
+    * Paradigm: reinforcement
+    * https://github.com/projectchrono/gym-chrono
+* ROBEL
+    * "ROBEL (RObotics BEnchmarks for Learning): a collection of affordable, reliable hardware designs for studying
+      dexterous manipulation and locomotion on real-world hardware"
+    * `Main webpage <https://sites.google.com/view/roboticsbenchmarks/>`__,
+      `Github repo <https://github.com/google-research/robel>`__
+
+
+.. csv-table:: Comparisons between different robot learning frameworks that provide environments. PL stands for perception learning, SRL for state representation learning, and AV for autonomous vehicles.
+    :header: "Name", "Supported OS", "Python", "Simulator", "Paradigm", "Robot", "Domain", "Last active"
+
+    "OpenAI Gym", "Linux, Mac OSX", "2.7, 3.5", "MuJoCo", "RL", "3D chars", "Manipulation, Locomotion", "few days ago"
+    "DeepMind Control Suite", "Ubuntu 14.04/16.04", "2.7, 3.5", "MuJoCo", "RL", "3D chars", "Locomotion, Control"
+    "Roboschool", "Ubuntu/Debian, Mac OSX", "3", "Bullet", "RL", "3D chars", "Locomotion, Control"
+    "Pybullet Gym", "Linux, Mac OSX, Windows", "2.7, 3.5", "PyBullet", "RL", "3D chars, Atlas", "Manipulation, Locomotion, Control", "8 months ago"
+    "GibsonEnv", "Ubuntu", "3.5", "Bullet", "PL/RL", "3D chars, 5 robots", "Perception, Navigation"
+    "Airsim", "Linux, Windows", "3.5+", "Unreal Engine/Unity", "IL/RL", "AV", "Navigation"
+    "Carla", "Ubuntu 16.04+, Windows", "2.7, 3.5", "Unreal Engine", "IL/RL", "AV", "Navigation"
+    "Surreal Robotics Suite", "Linux, Mac OSX", "3.5, 3.7", "MuJoCo", "IL/RL", "Baxter/Sawyer", "Manipulation"
+    "S-RL Toolbox", "Linux, Mac OSX, Windows", "3.5+", "PyBullet", "RL/SRL", "Kuka/OmniRobot", "Manipulation, Navigation"
+    "RLBench", "Linux, Mac OSX, Windows", "3.5+", "PyRep", "IL/RL/ML/MTL", "Franka Emika Panda", "Manipulation", "few days ago"
+    "gym-chrono", "Linux, Windows, OSX", "NS", "PyChrono", "RL", "Pendulum, Ant, Hexapod, Manipulator", "Manipulation, Locomotion, Control", "few days ago"
+    "ROBEL", "NS", "3.5+", "MuJoCo", "RL", "D'Claw, D'Kitty", "Hardware, Manipulation, Locomotion", "few days ago"
+    "PyRoboLearn", "Linux (Mac OSX*, Windows*)", "2.7, 3.5, 3.6", "Agnostic (PyBullet)", "IL/RL", "60+ robots", "Manipulation, Locomotion, Control", "few days ago"
+
+Note that except PRL none of these frameworks is modular nor flexible. PRL also has the advantage of being heavily documented.
+
+Full comparison with RLBench as it is the one that seems to be most similar to the proposed framework:
+
+- RLBench is only available in Python 3.* (not back compatible with Python 2.7), while PRL is available in both versions
+- RLBench uses the PyRep simulator while PRL is agnostic wrt the used simulator in principle
+- You currently can not load URDFs with PyRep (and thus with RLBench)
+- You have to specify the scene (environment) and the objects/robots in the scene beforehand in V-REP and generate a ttm
+  or ttt file in a static way.
+- RLBench focuses mostly on manipulation tasks but has the advantage of providing more than 100 tasks to users. However, note that currently these
+  are defined for the Franka Emika Panda manipulator.
+- PRL proposes more different robotic platforms, interfaces, and has in general more features (priority tasks, ROS
+  support, and others. See following `link <https://github.com/robotlearn/pyrobolearn/blob/master/pyrobolearn/README.rst>`__).
+- Regarding the 3D models that are available (in OBJ, and binary format but can be opened with VREP), I am currently not
+  sure if their redistribution is allowed especially without providing the license and proper attribution (see
+  following `link <https://github.com/robotlearn/pyrobolearn/blob/master/pyrobolearn/worlds/meshes/README.rst>`__).
+
+
+Models & Algorithms
+-------------------
+
+Models and algorithms depends on the use of a backend library (numpy, tensorflow, keras, pytorch, ...).
+Because PRL is using pytorch and numpy as backends, I will mostly focus on these.
+
+* Keras-RL:
+    * Model and algorithm coupled
+* rllab/garage
+    * Python 3.5+ (officially), old branch for Python 2 (for rllab)
+    * Backend: TensorFlow
+* rllib
+    * OS: Ubuntu 14.04, 16.04, 18.04 + Mac OSX 10.11, 10.12, 10.13, 10.14
+    * Python 2 and 3
+    * Backend: TensorFlow, PyTorch
+* pytorch
+    * OS: Linux, Mac, Windows
+    * Python 2.7, 3.5, 3.6, 3.7
+* stable-baselines
+    * OS: Ubuntu, Mac OSX, Windows 10
+    * Python >= 3.5
+    * Backend: TensorFlow
+* Catalyst
+    * Python 3.6+
+    * Backend: PyTorch 0.4.1+
+    * Modular and more flexible
+* rlpyt
+    * Backend: PyTorch
+    * https://github.com/astooke/rlpyt
+* Deep Reinforcement Learning Algorithms with PyTorch
+    * Backend: PyTorch
+    * https://github.com/p-christ/Deep-Reinforcement-Learning-Algorithms-with-PyTorch
+
+.. csv-table:: Learning models and algorithms
+    :header: "Name", "Supported OS", "Python", "Backend", "Flexible"
+
+    "rllab / garage", "Linux, Mac OSX", "3.5+", "TensorFlow", "No"
+    "rllib", "Ubuntu 1[4,6,8], Mac OSX 10.1[1-4]", "2, 3", "TensorFlow, PyTorch", "No"
+    "stable-baselines", "Linux, Mac OSX, Windows", "3.5", "TensorFlow", "No"
+    "Catalyst", "NS", "3.6+", "PyTorch", "Yes"
+    "rlpyt", "NS", "NS", "PyTorch", "Yes"
+    "DRL with PyTorch", "NS", "NS", "PyTorch", "No"
+    "PyRoboLearn", "Ubuntu 16.04/18.04", "2.7, 3.5, 3.6", "PyTorch", "Yes"