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Build Status

Cactus is a reference-free whole-genome alignment program, as well as a pagenome graph construction toolkit.

Getting Cactus

  • Use the precompiled binaries (Linux X86) or Docker image from the latest release
  • See below for details on building from source.

Align Genomes from Different Species

Align Genomes from the Same Species and Build Pangenome Graphs


Cactus uses many different algorithms and individual code contributions, principally from Joel Armstrong, Glenn Hickey, Mark Diekhans and Benedict Paten. We are particularly grateful to:

  • Yung H. Tsin and Nima Norouzi for contributing their 3-edge connected components program code, which is crucial in constructing the cactus graph structure, see: Tsin,Y.H., "A simple 3-edge-connected component algorithm," Theory of Computing Systems, vol.40, No.2, 2007, pp.125-142.
  • Bob Harris for providing endless support for his LastZ pairwise, blast-like genome alignment tool.
  • Melissa Jane Hubiz and Adam Siepel for halPhyloP and Phast.
  • Sneha Goenka and Yatish Turakhia for SegAlign, the GPU-accelerated version of LastZ.
  • Yan Gao et al. for abPOA
  • Heng Li for minigraph, minimap2, gfatools and dna-brnn
  • Dany Doerr for GFAffix, used to optionally clean pangenome graphs.
  • The vg team for vg, used to process pangenome graphs.
  • The authors of Mash

Mailing List

Please subscribe to the cactus-announce low-volume mailing list so we may reach about releases and other announcements.

Installing Manually From Source

Cactus requires Python >= 3.7 along with Python development headers and libraries

Clone cactus and submodules

git clone --recursive

Create the Python virtual environment. Install virtualenv first if needed with python3 -m pip install virtualenv.

cd cactus
virtualenv -p python3 cactus_env
echo "export PATH=$(pwd)/bin:\$PATH" >> cactus_env/bin/activate
echo "export PYTHONPATH=$(pwd)/lib:\$PYTHONPATH" >> cactus_env/bin/activate
source cactus_env/bin/activate
python3 -m pip install -U setuptools pip
python3 -m pip install -U .
python3 -m pip install -U -r ./toil-requirement.txt

If you have Docker installed, you can now run Cactus. All binaries, such as lastz and cactus-consolidated will be run via Docker. Singularity binaries can be used in place of docker binaries with the --binariesMode singularity flag. Note, you must use Singularity 2.3 - 2.6 or Singularity 3.1.0+. Singularity 3 versions below 3.1.0 are incompatible with cactus (see issue #55 and issue #60).

By default, cactus will use the image,<CACTUS_COMMIT> when running binaries. This is usually okay, but can be overridden with the CACTUS_DOCKER_ORG and CACTUS_DOCKER_TAG environment variables. For example, to use GPU release 2.4.4, run export CACTUS_DOCKER_TAG=v2.4.4-gpu before running cactus.

Compiling Binaries Locally

In order to compile the binaries locally and not use a Docker image, you need some dependencies installed. On Ubuntu (we've tested on 20.04 and 22.04), you can look at the Cactus Dockerfile for guidance. To obtain the apt-get command:

grep apt-get Dockerfile | head -1 | sed -e 's/RUN //g' -e 's/apt-get/sudo apt-get/g'

Progressive Cactus can be built on ARM cpus including on Mac (with packages installed via Brew), but Minigraph-Cactus is currently X86-only.

To build Cactus, run

make -j 8

In order to run the Minigraph-Cactus pipeline, you must also run


In order to toggle between local and Docker binaries, use the --binariesMode command line option. If --binariesMode is not specified, local binaries will be used if found in PATH, otherwise a Docker image will be used.