DeCovarT

DeCovarT

Overview

DeCovarT is an R package for bulk transcriptomic deconvolution that accounts for gene–gene covariance in purified reference populations. Bulk observations are modelled as Gaussian convolutions of cell-type means and covariances, with cellular proportions recovered on the open simplex via an unconstrained (additive logistic) parametrisation.

The main entry point is deconvolute_ratios(), which runs one or more solvers in parallel and returns estimated proportions plus optional benchmark metrics.

Seminar slides (iframe)

Doctorants seminar overview (Quarto reveal.js). Prefer full screen when presenting.

Pipeline Architecture

%%{init: {"theme": "sandstone"}}%%
flowchart TD
    A["Bulk RNA-seq mixture<br/>Genes × Samples"] --> C["Gene intersection,<br/>optional scaling"]
    B["Cell-type reference<br/>Means μ_j + covariances Σ_j"] --> C

    C --> D["deconvolute_ratios()<br/>Parallel solvers"]

    D --> E["DeCovarT<br/>Covariance-aware MLE<br/>ALR + marqLevAlg"]
    D --> F["First-generation methods<br/>NNLS · QP · GLS · rlm · ν-SVR"]

    E --> G["Proportion estimates<br/>on the simplex"]
    F --> G

    G --> H["Optional benchmark metrics<br/>vs true ratios"]
    G --> I["Correlation heatmaps<br/>and visualisation"]

    H --> J["Comparative evaluation"]
    I --> J

The diagram above summarises the end-to-end workflow.

This package combines Gaussian mixture convolution modelling, simplex reparametrisation (ALR / soft-max), analytic likelihood derivatives, and classical linear deconvolution baselines on bulk transcriptomic mixtures. Solver outputs remain method-specific; shared evaluation uses standardised proportion tables and optional ground-truth ratios from simulations.

Interactive package structure

Three graphs, regenerated with Rscript scripts/auxiliary/generate_package_network_functions.R. The estimation and interval network is the Gaussian-convolution fit. The simulation and benchmark network is the scenario generator and the ADEMP summaries. The visualisation network covers the Monte Carlo plots.

Built-in deconvolution algorithms

Algorithm	Interface	Notes / upstream
DeCovarT (Marquardt–Levenberg)	`deconvolute_ratios_Marquardt_Levenberg`	Covariance-aware MLE
Non-negative least squares	`deconvolute_ratios_nnls`	Lawson–Hanson NNLS
DeconRNASeq-style QP	`deconvolute_ratios_deconrnaseq`	Simplex QP via {limSolve}
Robust linear model (`rlm`)	`deconvolute_ratios_rlm`	ABIS / Monaco-style RLR
CIBERSORT-style $\nu$-SVR	`deconvolute_ratios_cibersort`	Linear-kernel SVR via {e1071}

All of the above ship with the package (no extra method packages required).

Links to the paper

arXiv:2309.09557 (also on HAL)
PDF: arXiv PDF

Installation

Once the package is on CRAN:

install.packages("DeCovarT")

Until then, install the development version from GitHub with {pak}:

if (!requireNamespace("pak", quietly = TRUE)) {
  install.packages(
    "pak",
    repos = sprintf(
      "https://r-lib.github.io/p/pak/stable/%s/%s/%s",
      .Platform$pkgType,
      R.Version()$os,
      R.Version()$arch
    )
  )
}
pak::pkg_install("bastienchassagnol/DeCovarT")

Alternatively with {remotes}:

# install.packages("remotes")
remotes::install_github("bastienchassagnol/DeCovarT")

Developer setup (pre-commit)

Contributors should install pre-commit hooks (Air formatting, {lintr}, parsable R). From R:

# install.packages(c("precommit", "lintr"))
precommit::install_precommit()
precommit::use_precommit()

Or from the shell (after pre-commit is on PATH):

pre-commit install
pre-commit run --all-files

Edit README.qmd, then regenerate GitHub Flavoured Markdown locally:

quarto render README.qmd
git add README.qmd README.md

CI fails the pull request if committed README.md is stale relative to README.qmd (see .github/workflows/render-readme.yaml). On main, the same workflow can commit a fresh render when needed, following the quarto-ext render-readme pattern.

See the contributor guide for the full contributor guide.

Continuous integration

GitHub Actions on this repository currently cover:

R-CMD-check — R CMD check on push / pull requests
pre-commit — the same local hooks on CI
render-readme — Quarto GFM render; verify on PRs, commit on main
test-coverage — Codecov reporting (commit message contains test coverage)
pkgdown — documentation site on GitHub Pages
article generation — optional latexmk build of article/main_layout.tex when the commit message contains article generation (PDF artefact + docs/article/main.pdf on Pages)
R-hub — optional Ubuntu + Windows checks (workflow_dispatch)
version update — optional DESCRIPTION bumps from commit messages or manual dispatch

Documentation

Package website: https://bastienchassagnol.github.io/DeCovarT/

Vignettes

In an R session, use ?DeCovarT::deconvolute_ratios (or any other exported function) for help pages.

Troubleshooting and issues

Contributor guidance and common development pitfalls: contributor guide
Bug reports and feature requests: GitHub issues

Pull requests are welcome.

The generative model of DeCovarT

Constrained DeCovarT maps unconstrained coordinates $\boldsymbol{\rho}{i}\in\mathbb{R}^{J-1}$ to cellular proportions $\boldsymbol{p}{i}$ on the open simplex via a regularised soft-max $\boldsymbol{\psi}$, then forms the bulk observation as a Gaussian convolution of cell-type profiles $\boldsymbol{x}{j}\sim\mathcal{N}{G}(\boldsymbol{\mu}{j},\boldsymbol{\Sigma}{j})$:

$$ \boldsymbol{y}{i},|,\cdot \sim\mathcal{N}{G}!\Bigl( \boldsymbol{\mu}\boldsymbol{p}{i},; \sum{j=1}^{J}p_{ji}^{2}\boldsymbol{\Sigma}_{j} \Bigr). $$

%%{init: {
  "theme": "sandstone",
  "flowchart": { "curve": "basis" }
}}%%
flowchart TB
  subgraph plateJ["j = 1,...,J"]
    direction TB
    mu["μ_j"]
    Sj["Σ_j"]
    xj(("x_j"))
    mu --> xj
    Sj --> xj
  end

  subgraph plateI["i = 1,...,N"]
    direction TB
    rho(("ρ_i"))
    p["p_i = ψ(ρ_i)"]
    y(["y_i"])
    rho -->|"ψ soft-max"| p
    p -.-> y
  end

  xj -.->|"y_i = μ p_i"| y

  classDef param fill:#ffffff,stroke:#0f172a,stroke-width:1.5px;
  classDef latent fill:#ffffff,stroke:#0f172a,stroke-width:1.5px;
  classDef det fill:#ffffff,stroke:#0f172a,stroke-width:1.5px,stroke-dasharray:5 3;
  classDef obs fill:#cbd5e1,stroke:#0f172a,stroke-width:1.5px,stroke-dasharray:5 3;

  class mu,Sj param;
  class rho,xj latent;
  class p det;
  class y obs;

The diagram above shows the constrained graphical model.

Forward map $\boldsymbol{\psi}:\boldsymbol{\rho}\mapsto\boldsymbol{p}$ ($C^{2}$-diffeomorphism):

$$ p_{j}=\frac{e^{\rho_{j}}}{\sum_{k<J}e^{\rho_{k}}+1}\ (j<J),\qquad p_{J}=\frac{1}{\sum_{k<J}e^{\rho_{k}}+1},\qquad \boldsymbol{\psi}^{-1}(\boldsymbol{p})=\bigl(\ln(p_{j}/p_{J})\bigr)_{j<J}. $$

Compiling the LaTeX article

Source files: article/main_layout.tex and article/appendix_layout.tex (bibliography: article/decovart_library.bib and article/packages.bib). DAG panels in Fig.~DAG-model are drawn with tikz-bayesnet.

Published PDF: the peer-reviewed / preprint PDF is on arXiv:2309.09557. When a main commit message contains article generation, CI also builds article/main_layout.tex and may publish docs/article/main.pdf on the pkgdown site.

From the repository root, generate article/main_layout.pdf locally with:

cd article
latexmk -pdf -f -interaction=nonstopmode -file-line-error -synctex=1 main_layout.tex