Add trajectory transformer (#17141)

* Add trajectory transformer


Fix model init


Fix end of lines for .mdx files

Add trajectory transformer model to toctree

Add forward input docs

Fix docs, remove prints, simplify prediction test

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Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
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Co-authored-by: Lysandre Debut <lysandre@huggingface.co>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Update docs, more descriptive comments

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Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Update readme

Small comment update and add conversion script

Rebase and reformat

Fix copies

Fix rebase, remove duplicates

Fix rebase, remove duplicates

* Remove tapex

* Remove tapex

* Remove tapex

docs/source/en/_toctree.yml

@@ -342,6 +342,8 @@
       title: TAPAS
     - local: model_doc/tapex
       title: TAPEX
+    - local: model_doc/trajectory_transformer
+      title: Trajectory Transformer
     - local: model_doc/transfo-xl
       title: Transformer XL
     - local: model_doc/trocr

docs/source/en/index.mdx

@@ -142,6 +142,7 @@ The library currently contains JAX, PyTorch and TensorFlow implementations, pret
 1. **[T5v1.1](model_doc/t5v1.1)** (from Google AI) released in the repository [google-research/text-to-text-transfer-transformer](https://github.com/google-research/text-to-text-transfer-transformer/blob/main/released_checkpoints.md#t511) by Colin Raffel and Noam Shazeer and Adam Roberts and Katherine Lee and Sharan Narang and Michael Matena and Yanqi Zhou and Wei Li and Peter J. Liu.
 1. **[TAPAS](model_doc/tapas)** (from Google AI) released with the paper [TAPAS: Weakly Supervised Table Parsing via Pre-training](https://arxiv.org/abs/2004.02349) by Jonathan Herzig, Paweł Krzysztof Nowak, Thomas Müller, Francesco Piccinno and Julian Martin Eisenschlos.
 1. **[TAPEX](model_doc/tapex)** (from Microsoft Research) released with the paper [TAPEX: Table Pre-training via Learning a Neural SQL Executor](https://arxiv.org/abs/2107.07653) by Qian Liu, Bei Chen, Jiaqi Guo, Morteza Ziyadi, Zeqi Lin, Weizhu Chen, Jian-Guang Lou.
+1. **[Trajectory Transformer](model_doc/trajectory_transformers)** (from the University of California at Berkeley) released with the paper [Offline Reinforcement Learning as One Big Sequence Modeling Problem](https://arxiv.org/abs/2106.02039) by Michael Janner, Qiyang Li, Sergey Levine
 1. **[Transformer-XL](model_doc/transfo-xl)** (from Google/CMU) released with the paper [Transformer-XL: Attentive Language Models Beyond a Fixed-Length Context](https://arxiv.org/abs/1901.02860) by Zihang Dai*, Zhilin Yang*, Yiming Yang, Jaime Carbonell, Quoc V. Le, Ruslan Salakhutdinov.
 1. **[TrOCR](model_doc/trocr)** (from Microsoft), released together with the paper [TrOCR: Transformer-based Optical Character Recognition with Pre-trained Models](https://arxiv.org/abs/2109.10282) by Minghao Li, Tengchao Lv, Lei Cui, Yijuan Lu, Dinei Florencio, Cha Zhang, Zhoujun Li, Furu Wei.
 1. **[UniSpeech](model_doc/unispeech)** (from Microsoft Research) released with the paper [UniSpeech: Unified Speech Representation Learning with Labeled and Unlabeled Data](https://arxiv.org/abs/2101.07597) by Chengyi Wang, Yu Wu, Yao Qian, Kenichi Kumatani, Shujie Liu, Furu Wei, Michael Zeng, Xuedong Huang.
@@ -259,6 +260,7 @@ Flax), PyTorch, and/or TensorFlow.
 |            Swin             |       ❌       |       ❌       |       ✅        |         ✅         |      ❌      |
 |             T5              |       ✅       |       ✅       |       ✅        |         ✅         |      ✅      |
 |            TAPAS            |       ✅       |       ❌       |       ✅        |         ✅         |      ❌      |
+|   Trajectory Transformer    |       ❌       |       ❌       |       ✅        |         ❌         |      ❌      |
 |       Transformer-XL        |       ✅       |       ❌       |       ✅        |         ✅         |      ❌      |
 |            TrOCR            |       ❌       |       ❌       |       ✅        |         ❌         |      ❌      |
 |          UniSpeech          |       ❌       |       ❌       |       ✅        |         ❌         |      ❌      |

docs/source/en/model_doc/trajectory_transformer.mdx

@@ -0,0 +1,49 @@
+<!--Copyright 2022 The HuggingFace Team. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+the License. You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+specific language governing permissions and limitations under the License.
+-->
+
+# Trajectory Transformer
+
+## Overview
+
+The Trajectory Transformer model was proposed in [Offline Reinforcement Learning as One Big Sequence Modeling Problem](https://arxiv.org/abs/2106.02039)  by Michael Janner, Qiyang Li, Sergey Levine.
+
+The abstract from the paper is the following:
+
+*Reinforcement learning (RL) is typically concerned with estimating stationary policies or single-step models,
+leveraging the Markov property to factorize problems in time. However, we can also view RL as a generic sequence
+modeling problem, with the goal being to produce a sequence of actions that leads to a sequence of high rewards.
+Viewed in this way, it is tempting to consider whether high-capacity sequence prediction models that work well
+in other domains, such as natural-language processing, can also provide effective solutions to the RL problem.
+To this end, we explore how RL can be tackled with the tools of sequence modeling, using a Transformer architecture
+to model distributions over trajectories and repurposing beam search as a planning algorithm. Framing RL as sequence
+modeling problem simplifies a range of design decisions, allowing us to dispense with many of the components common
+in offline RL algorithms. We demonstrate the flexibility of this approach across long-horizon dynamics prediction,
+imitation learning, goal-conditioned RL, and offline RL. Further, we show that this approach can be combined with
+existing model-free algorithms to yield a state-of-the-art planner in sparse-reward, long-horizon tasks.*
+
+Tips:
+
+This Transformer is used for deep reinforcement learning. To use it, you need to create sequences from
+actions, states and rewards from all previous timesteps. This model will treat all these elements together
+as one big sequence (a trajectory).
+
+This model was contributed by [CarlCochet](https://huggingface.co/CarlCochet). The original code can be found [here](https://github.com/jannerm/trajectory-transformer).
+
+## TrajectoryTransformerConfig
+
+[[autodoc]] TrajectoryTransformerConfig
+
+
+## TrajectoryTransformerModel
+
+[[autodoc]] TrajectoryTransformerModel
+    - forward