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Gretel Synthetics

Gobs the cat
An open source synthetic data library from

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Try it out now!

If you want to quickly discover gretel-synthetics, simply click the button below and follow the tutorials!

Open in Colab

Check out additional examples here.

Getting Started

By default, we do not install Tensorflow via pip as many developers and cloud services such as Google Colab are running customized versions for their hardware.

pip install -U .


pip install gretel-synthetics


$ pip install jupyter
$ jupyter notebook

When the UI launches in your browser, navigate to examples/synthetic_records.ipynb and get generating!

If you want to install gretel-synthetics locally and use a GPU (recommended):

  1. Create a virtual environment (e.g. using conda)

$ conda create --name tf --python=3.8
  1. Activate the virtual environment

$ conda activate tf
  1. Run the setup script ./setup-utils/

The last step will install all the necessary software packages for GPU usage, tensorflow=2.4 and gretel-synthetics. Note that this script works only for Ubuntu 18.04. You might need to modify it for other OS versions.


This package allows developers to quickly get immersed with synthetic data generation through the use of neural networks. The more complex pieces of working with libraries like Tensorflow and differential privacy are bundled into friendly Python classes and functions. There are two high level modes that can be utilized.

Simple Mode

The simple mode will train line-per-line on an input file of text. When generating data, the generator will yield a custom object that can be used a variety of different ways based on your use case. This notebook demonstrates this mode.

DataFrame Mode

This library supports CSV / DataFrames natively using the DataFrame “batch” mode. This module provided a wrapper around our simple mode that is geared for working with tabular data. Additionally, it is capabable of handling a high number of columns by breaking the input DataFrame up into “batches” of columns and training a model on each batch. This notebook shows an overview of using this library with DataFrames natively.


There are four primary components to be aware of when using this library.

  1. Configurations. Configurations are classes that are specific to an underlying ML engine used to train and generate data. An example would be using TensorFlowConfig to create all the necessary parameters to train a model based on TF. LocalConfig is aliased to TensorFlowConfig for backwards compatability with older versions of the library. A model is saved to a designated directory, which can optionally be archived and utilized later.

  2. Tokenizers. Tokenizers convert input text into integer based IDs that are used by the underlying ML engine. These tokenizers can be created and sent to the training input. This is optional, and if no specific tokenizer is specified then a default one will be used. You can find an example here that uses a simple char-by-char tokenizer to build a model from an input CSV. When training in a non-differentially private mode, we suggest using the default SentencePiece tokenizer, an unsupervised tokenizer that learns subword units (e.g., byte-pair-encoding (BPE) [Sennrich et al.]) and unigram language model [Kudo.]) for faster training and increased accuracy of the synthetic model.

  3. Training. Training a model combines the configuration and tokenizer and builds a model, which is stored in the designated directory, that can be used to generate new records.

  4. Generation. Once a model is trained, any number of new lines or records can be generated. Optionally, a record validator can be provided to ensure that the generated data meets any constraints that are necessary. See our notebooks for examples on validators.


In addition to the four primary components, the gretel-synthetics package also ships with a set of utilities that are helpful for training advanced synthetics models and evaluating synthetic datasets.

Some of this functionality carries large dependencies, so they are shipped as an extra called utils. To install these dependencies, you may run

pip install gretel-synthetics[utils]

For additional details, please refer to the Utility module API docs.

Differential Privacy

Differential privacy support for our TensorFlow mode is built on the great work being done by the Google TF team and their TensorFlow Privacy library.

When utilizing DP, we currently recommend using the character tokenizer as it will only create a vocabulary of single tokens and removes the risk of sensitive data being memorized as actual tokens that can be replayed during generation.

There are also a few configuration options that are notable such as:

  • predict_batch_size should be set to 1

  • dp should be enabled

  • learning_rate, dp_noise_multiplier, dp_l2_norm_clip, and dp_microbatches can be adjusted to achieve various epsilon values.

  • reset_states should be disabled

Please see our example Notebook for training a DP model based on the Netflix Prize dataset.


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