README.md

---
language: de
license: mit
thumbnail: https://static.tildacdn.com/tild6438-3730-4164-b266-613634323466/german_bert.png
tags:
- exbert
---

<a href="https://huggingface.co/exbert/?model=bert-base-german-cased">
	<img width="300px" src="https://cdn-media.huggingface.co/exbert/button.png">
</a>

# German BERT
![bert_image](https://static.tildacdn.com/tild6438-3730-4164-b266-613634323466/german_bert.png)

## Table of Contents
- [Model Details](#model-details)
- [Uses](#uses)
- [Risks, Limitations and Biases](#risks-limitations-and-biases)
- [Training](#training)
- [Evaluation](#evaluation)
- [Environmental Impact](#environmental-impact)
- [Model Card Contact](#model-card-contact)
- [How to Get Started With the Model](#how-to-get-started-with-the-model)

## Model Details
- **Model Description:**
German BERT allows the developers working with text data in German to be more efficient with their natural language processing (NLP) tasks. 
- **Developed by:**  
  - [Branden Chan](branden.chan@deepset.ai)
  - [Timo Möller](timo.moeller@deepset.ai)
  - [Malte Pietsch](malte.pietsch@deepset.ai)
  - [Tanay Soni](tanay.soni@deepset.ai)
- **Model Type:** Fill-Mask
- **Language(s):** German
- **License:** MIT
- **Parent Model:** See the [BERT base cased model](https://huggingface.co/bert-base-cased) for more information about the BERT base model.
- **Resources for more information:**
	- **Update October 2020:** [Research Paper](https://aclanthology.org/2020.coling-main.598/)  
  - [Website: German BERT](https://deepset.ai/german-bert)
  - [GitRepo: FARM](https://github.com/deepset-ai/FARM)
  - [Git Repo: Haystack](https://github.com/deepset-ai/haystack/)


## Uses

#### Direct Use

This model can be used for masked language modelling.

## Risks, Limitations and Biases
**CONTENT WARNING: Readers should be aware this section contains content that is disturbing, offensive, and can propagate historical and current stereotypes.**

Significant research has explored bias and fairness issues with language models (see, e.g., [Sheng et al. (2021)](https://aclanthology.org/2021.acl-long.330.pdf) and [Bender et al. (2021)](https://dl.acm.org/doi/pdf/10.1145/3442188.3445922)).

## Training

#### Training Data
**Training data:** Wiki, OpenLegalData, News (~ 12GB) 
- As training data we used the latest German Wikipedia dump (6GB of raw txt files), the OpenLegalData dump (2.4 GB) and news articles (3.6 GB).

- The data dumps were cleaned with tailored scripts and segmented sentences with spacy v2.1. To create tensorflow records the model developers used the recommended *sentencepiece* library for creating the word piece vocabulary and tensorflow scripts to convert the text to data usable by BERT.

**Update April 3rd, 2020**: the model developers updated the vocabulary file on deepset's s3 to conform with the default tokenization of punctuation tokens. 

For details see the related [FARM issue](https://github.com/deepset-ai/FARM/issues/60). If you want to use the old vocab we have also uploaded a ["deepset/bert-base-german-cased-oldvocab"](https://huggingface.co/deepset/bert-base-german-cased-oldvocab) model.
 

#### Training Procedure
- We trained using Google's Tensorflow code on a single cloud TPU v2 with standard settings.
- We trained 810k steps with a batch size of 1024 for sequence length 128 and 30k steps with sequence length 512. Training took about 9 days.

See https://deepset.ai/german-bert for more details


## Hyperparameters

```
batch_size = 1024
n_steps = 810_000
max_seq_len = 128 (and 512 later)
learning_rate = 1e-4
lr_schedule = LinearWarmup
num_warmup_steps = 10_000
```

## Evaluation


* **Eval data:** Conll03 (NER), GermEval14 (NER), GermEval18 (Classification), GNAD (Classification)  

#### Performance
During training we monitored the loss and evaluated different model checkpoints on the following German datasets:

- germEval18Fine: Macro f1 score for multiclass sentiment classification
- germEval18coarse: Macro f1 score for binary sentiment classification
- germEval14: Seq f1 score for NER (file names deuutf.\*)
- CONLL03: Seq f1 score for NER
- 10kGNAD: Accuracy for document classification

Even without thorough hyperparameter tuning, we observed quite stable learning especially for our German model. Multiple restarts with different seeds produced quite similar results.
  
![performancetable](https://thumb.tildacdn.com/tild3162-6462-4566-b663-376630376138/-/format/webp/Screenshot_from_2020.png)  

We further evaluated different points during the 9 days of pre-training and were astonished how fast the model converges to the maximally reachable performance. We ran all 5 downstream tasks on 7 different model checkpoints - taken at 0 up to 840k training steps (x-axis in figure below). Most checkpoints are taken from early training where we expected most performance changes. Surprisingly, even a randomly initialized BERT can be trained only on labeled downstream datasets and reach good performance (blue line, GermEval 2018 Coarse task, 795 kB trainset size).

![checkpointseval](https://thumb.tildacdn.com/tild6335-3531-4137-b533-313365663435/-/format/webp/deepset_checkpoints.png)  


## Environmental Impact

Carbon emissions can be estimated using the [Machine Learning Impact calculator](https://mlco2.github.io/impact#compute) presented in [Lacoste et al. (2019)](https://arxiv.org/abs/1910.09700). We present the hardware type based on the [associated paper](https://arxiv.org/pdf/2105.09680.pdf).


- **Hardware Type:** Tensorflow code on a single cloud TPU v2 

- **Hours used:** 216 (9 days)

- **Cloud Provider:** GCP

- **Compute Region:** [More information needed]

- **Carbon Emitted:** [More information needed]


## Model Card Contact

<details>
<summary>Click to expand</summary>
  

![deepset logo](https://raw.githubusercontent.com/deepset-ai/FARM/master/docs/img/deepset_logo.png)

We bring NLP to the industry via open source!  
Our focus: Industry specific language models & large scale QA systems.  


Get in touch:
[Twitter](https://twitter.com/deepset_ai) | [LinkedIn](https://www.linkedin.com/company/deepset-ai/) | 

</details>


## How to Get Started With the Model

```python
from transformers import AutoTokenizer, AutoModelForMaskedLM

tokenizer = AutoTokenizer.from_pretrained("bert-base-german-cased")

model = AutoModelForMaskedLM.from_pretrained("bert-base-german-cased")

```