Zoobot

:tada: Zoobot 2.0 is now available. Bigger and better models with streamlined finetuning. Blog, paper :tada:

Zoobot classifies galaxy morphology with deep learning. <!-- At Galaxy Zoo, we use Zoobot to help our volunteers classify the galaxies in all our recent catalogues: GZ DECaLS, GZ DESI, GZ Rings and GZ Cosmic Dawn. -->

Zoobot is trained using millions of answers by Galaxy Zoo volunteers. This code will let you retrain Zoobot to accurately solve your own prediction task.

• Install
• Quickstart
• Worked Examples
• Pretrained Weights
• Datasets
• Documentation (for understanding/reference)
• Mailing List (for updates)

Installation

You can retrain Zoobot in the cloud with a free GPU using this Google Colab notebook. To install locally, keep reading.

Download the code using git:

git clone git@github.com:mwalmsley/zoobot.git

And then install Zoobot (and PyTorch, if not already installed):

pip install -e "zoobot[pytorch]"

This installs the downloaded Zoobot code using pip editable mode so you can easily change the code locally. Zoobot is also available directly from pip (pip install zoobot[option]). Only use this if you are sure you won't be making changes to Zoobot itself. For Google Colab, use pip install zoobot[pytorch_colab]

To use a GPU, you must already have CUDA installed and matching the versions above. I share my install steps here. GPUs are optional - Zoobot will run retrain fine on CPU, just slower.

Quickstart

The Colab notebook is the quickest way to get started. Alternatively, the minimal example below illustrates how Zoobot works.

Let's say you want to find ringed galaxies and you have a small labelled dataset of 500 ringed or not-ringed galaxies. You can retrain Zoobot to find rings like so:

```python import pandas as pd from galaxydatasets.pytorch.galaxydatamodule import CatalogDataModule from zoobot.pytorch.training import finetune

csv with 'ring' column (0 or 1) and 'file_loc' column (path to image)

labelleddf = pd.readcsv('/your/path/somelabelledgalaxies.csv')

datamodule = CatalogDataModule( labelcols=['ring'], catalog=labelleddf, batch_size=32 # will automatically apply default augmentations )

load trained Zoobot model

model = finetune.FinetuneableZoobotClassifier(checkpointloc, numclasses=2)

retrain to find rings

trainer = finetune.gettrainer(savedir) trainer.fit(model, datamodule) ```

Then you can make predict if new galaxies have rings:

```python from zoobot.pytorch.predictions import predictoncatalog

csv with 'file_loc' column (path to image). Zoobot will predict the labels.

unlabelleddf = pd.readcsv('/your/path/someunlabelledgalaxies.csv')

predictoncatalog.predict( unlabelleddf, model, labelcols=['ring'], # only used for saveloc='/your/path/finetunedpredictions.csv' ) ```

Zoobot includes many guides and working examples - see the Getting Started section below.

Getting Started

I suggest starting with the Colab notebook or the worked examples below, which you can copy and adapt.

For context and explanation, see the documentation.

Pretrained models are listed here and available on HuggingFace

Worked Examples

• pytorch/examples/finetuning/finetunebinaryclassification.py
• pytorch/examples/finetuning/finetunecountsfull_tree.py
• pytorch/examples/representations/get_representations.py
• pytorch/examples/trainmodelon_catalog.py (only necessary to train from scratch)

There is more explanation and an API reference on the docs.

(Optional) Install PyTorch with CUDA

If you're not using a GPU, skip this step

I highly recommend using conda (or mamba, same thing but faster) to do this. Conda will handle both creating a new virtual environment (conda create) and installing CUDA (cudatoolkit, cudnn)

CUDA 12.8 for PyTorch 2.7.0:

conda create --name zoobot39_torch python==3.9
conda activate zoobot39_torch
conda install nvidia/label/cuda-12.8.1::cuda
conda install nvidia/label/cuda-12.8.1::cuda-toolkit

Recent release features (v2.0.0)

• New in 2.0.1 Add greyscale encoders. Use hf_hub:mwalmsley/zoobot-encoder-greyscale-convnext_nano or similar.
• New pretrained architectures: ConvNeXT, EfficientNetV2, MaxViT, and more. Each in several sizes.
• Reworked finetuning procedure. All these architectures are finetuneable through a common method.
• Reworked finetuning options. Batch norm finetuning removed. Cosine schedule option added.
• Reworked finetuning saving/loading. Auto-downloads encoder from HuggingFace.
• Now supports regression finetuning (as well as multi-class and binary). See pytorch/examples/finetuning
• Updated timm to 0.9.10, allowing latest model architectures. Previously downloaded checkpoints may not load correctly!
• (internal until published) GZ Evo v2 now includes Cosmic Dawn (HSC H2O). Significant performance improvement on HSC finetuning. Also now includes GZ UKIDSS (dragged from our archives).
• Updated pytorch to 2.1.0
• Added support for webdatasets (only recommended for large-scale distributed training)
• Improved per-question logging when training from scratch
• Added option to compile encoder for max speed (not recommended for finetuning, only for pretraining).
• Deprecates TensorFlow. The CS research community focuses on PyTorch and new frameworks like JAX.

Contributions are very welcome and will be credited in any future work. Please get in touch! See CODEOFCONDUCT.md for more.

Benchmarks and Replication - Training from Scratch

The benchmarks folder contains slurm and Python scripts to train Zoobot 1.0 from scratch.

Training Zoobot using the GZ DECaLS dataset option will create models very similar to those used for the GZ DECaLS catalogue and shared with the early versions of this repo. The GZ DESI Zoobot model is trained on additional data (GZD-1, GZD-2), as the GZ Evo Zoobot model (GZD-1/2/5, Hubble, Candels, GZ2).

Pretraining is becoming increasingly complex and is now partially refactored out to a separate repository. We are gradually migrating this zoobot repository to focus on finetuning.

Citing

If you use this software, or otherwise wish to cite Zoobot as a software package, please use the JOSS paper:

@article{Walmsley2023, doi = {10.21105/joss.05312}, url = {https://doi.org/10.21105/joss.05312}, year = {2023}, publisher = {The Open Journal}, volume = {8}, number = {85}, pages = {5312}, author = {Mike Walmsley and Campbell Allen and Ben Aussel and Micah Bowles and Kasia Gregorowicz and Inigo Val Slijepcevic and Chris J. Lintott and Anna M. m. Scaife and Maja Jabłońska and Kosio Karchev and Denise Lanzieri and Devina Mohan and David O’Ryan and Bharath Saiguhan and Crisel Suárez and Nicolás Guerra-Varas and Renuka Velu}, title = {Zoobot: Adaptable Deep Learning Models for Galaxy Morphology}, journal = {Journal of Open Source Software} } 

You might be interested in reading papers using Zoobot:

• Galaxy Zoo DECaLS: Detailed visual morphology measurements from volunteers and deep learning for 314,000 galaxies (2022)
• A Comparison of Deep Learning Architectures for Optical Galaxy Morphology Classification (2022)
• Practical Galaxy Morphology Tools from Deep Supervised Representation Learning (2022)
• Towards Foundation Models for Galaxy Morphology (2022)
• Harnessing the Hubble Space Telescope Archives: A Catalogue of 21,926 Interacting Galaxies (2023)
• Galaxy Zoo DESI: Detailed morphology measurements for 8.7M galaxies in the DESI Legacy Imaging Surveys (2023)
• Galaxy mergers in Subaru HSC-SSP: A deep representation learning approach for identification, and the role of environment on merger incidence (2023)
• Rare Galaxy Classes Identified In Foundation Model Representations (2023)
• Astronomaly at Scale: Searching for Anomalies Amongst 4 Million Galaxies (2024)
• Transfer learning for galaxy feature detection: Finding Giant Star-forming Clumps in low redshift galaxies using Faster R-CNN (2024)
• Euclid preparation. Measuring detailed galaxy morphologies for Euclid with Machine Learning (2024)
• Scaling Laws for Galaxy Images (2024, preprint)
• Euclid Q1: First visual morphology catalogue (2025, preprint)
• Euclid Q1, A first look at the fraction of bars in massive galaxies at z < 1 (2025, preprint)
• Euclid Q1: The Strong Lensing Discovery Engine A -- System overview and lens catalogue (2025, preprint)
• Euclid Q1. The Strong Lensing Discovery Engine C: Finding lenses with machine learning (2025, preprint)
• Euclid Q1. The Strong Lensing Discovery Engine D -- Double-source-plane lens candidates (2025, preprint)
• Euclid Q1. The Strong Lensing Discovery Engine E -- Ensemble classification of strong gravitational lenses: lessons for Data Release 1 (2025, preprint)
• Euclid: Q1: A census of dwarf galaxies across a range of distances and environments (2025, preprint)
• Euclid Q1: Exploring galaxy morphology across cosmic time through Sersic fits (2025, preprint)
• Galaxy Zoo Evo: 107M volunteer labels for 823k galaxy images (2025, submitted)

Many other works use Zoobot indirectly via the Galaxy Zoo DECaLS and Galaxy Zoo DESI morphology catalogs, for example:

• Galaxy zoo: stronger bars facilitate quenching in star-forming galaxies (2022)
• The Effect of Environment on Galaxy Spiral Arms, Bars, Concentration, and Quenching (2022)
• Galaxy Zoo: kinematics of strongly and weakly barred galaxies (2023)
• Dependence of galactic bars on the tidal density field in the SDSS (2023)
• Galaxy Zoo DESI: large-scale bars as a secular mechanism for triggering AGN (2024)
• Galaxy zoo: stronger bars facilitate quenching in star-forming galaxies (2024, submitted)
• Uncovering Tidal Treasures: Automated Classification of Faint Tidal Features in DECaLS Data (2024, submitted)

Zoobot is deployed on the Euclid pipeline to produce the OU-MER morphology catalog. This is available as part of each Euclid data release (currently internal only, public release of Q1 data anticipated in Q2 2025).