sc-concept 0.2.2

code for scConcept

scConcept

This repository contains the python package to train and use scConcept (Single-cell contrastive cell pre-training) method for single-cell transcriptomics.

Installation

You need to have Python 3.12 or newer installed on your system. If you don't have Python installed, we recommend installing uv.

Default installation

Install the latest release of sc-concept from PyPI:

pip install sc-concept

Latest development version

To install the latest development version directly from GitHub:

pip install git+https://github.com/theislab/scConcept.git@main

Training from scratch with Flash Attention

The standard installation is enough for loading pretrained models, extracting embeddings, and light adaptation. If you want to train scConcept from scratch with Flash Attention, use one of the following options.

1. Recommended: cd to the project root and run ./scripts/setup_env.sh, which installs uv if needed and creates a virtual environment with the training dependencies.

2. Manual: make sure a CUDA-enabled version of PyTorch is installed. More information is available in the PyTorch installation guide. Then install Flash Attention:

MAX_JOBS=4 pip install "flash-attn>=2.7" --no-build-isolation

This can take up to an hour depending on the system specifications and whether a pre-built release of flash-attn is available for your exact versions of Python, PyTorch, and CUDA. If this takes long, we recommend using the setup script instead.

How to use

scConcept provides a simple API to load and adapt pre-trained models and extract embeddings from scRNA-seq data. Here's a basic example:

from concept import scConcept
import scanpy as sc

# Load your single-cell data
adata = sc.read_h5ad("your_data.h5ad")

# Initialize scConcept and load a pretrained model
concept = scConcept(cache_dir='./cache/')

# Option 1: Load a model directly from HuggingFace
concept.load_config_and_model(model_name='corpus40M-model30M') 

# Option 2: Load any local model
concept.load_config_and_model(
    config='<path-to-config.yaml>',
    model_path='<path-to-model.ckpt>',
    gene_mappings_path='<path-to-gene-mappings-directory>',
)

# scConcept accepts Gene Ensemble IDs as input. You can use built-in helper methods to do the mapping if needed:
adata.var['gene_id'] = concept.map_gene_names_to_ids(
    species='hsapiens', # see concept.species for available species names
    gene_names=adata.var_names.tolist(),
)

# Extract embeddings --> adata.var['gene_id']: ENSGXXXXXXXXXXX
result = concept.extract_embeddings(adata=adata, gene_id_column='gene_id')

# Use embeddings for downstream analysis
adata.obsm['X_scConcept'] = result['cls_cell_emb']

Model adaptation

# Adapt a pre-trained model on your own data
concept.train(adata, max_steps=10000, batch_size=128) 

# Important: For multiple datasets pass them separately
concept.train([adata1, adata2, ...], max_steps=20000, batch_size=128) 

result = concept.extract_embeddings(adata=adata, gene_id_column='gene_id')
adata.obsm['X_scConcept_adapted'] = result['cls_cell_emb']

Large-scale pre-training from scratch

scConcept.train() is only for light adaptation of pretrained models or small trainings on the fly. Use train.py for distributed model pre-training from scratch over large corpus of data.

Before using train.py follow the instructions on lamindb for setting up a lamin instance.

Troubleshooting

If you encounter an error when loading a pre-trained model, try the following:

1. Remove the repository and clone the most recent version
2. Remove the cache directory (cache/ by default)
3. Run again

This will force a fresh download of the pre-trained model and should resolve most loading issues.

Citation

Bahrami, M., Tejada-Lapuerta, A., Becker, S., Hashemi G, F.S. and Theis, F.J., 2025. scConcept: Contrastive pretraining for technology-agnostic single-cell representations beyond reconstruction. bioRxiv, pp.2025-10. doi: https://doi.org/10.1101/2025.10.14.682419