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gratia
What gratia is
gratia is free desktop software providing graphics and utility functions for generalized additive models fitted with the mgcv R package. It is designed for people working with GAMs in the tidyverse. The draw() function uses ggplot2 to display smooth and parametric contributions, while derivatives() estimates derivatives of fitted smooths with finite differences. The package supplies pointwise and simultaneous intervals, diagnostic plots through appraise() for supported GAM, GLM, and linear-model fits, and tidyverse-compatible representations of estimated smooths. It integrates with mgcv, ggplot2, and tidyverse workflows and includes scripting support, regression-model utilities, statistical tests, and Bayesian analysis. Installation is listed through CRAN, GitHub, and rOpenSci’s R Universe. The project uses the MIT license and names Gavin L. Simpson as author and maintainer. It describes development as active and experimental parallel processing for smooth_estimates() and basis(). Specialist smoothers using mrf, sw, and sf bases are not currently supported, and the getting-started guide points users to help pages and examples because documentation is limited.
Who it suits
It suits analysts and developers working with mgcv GAMs in tidyverse-based R workflows. Users needing unsupported specialist smoothers or extensive introductory documentation may need alternatives or additional guidance.
What it does well
- Free MIT-licensed R package
- ggplot2 plots for GAM contributions
- Derivative and interval estimates
- Diagnostic plots for supported models
- CRAN, GitHub, and R Universe installation
What to know first
- mrf, sw, and sf smoothers unsupported
- Documentation is currently limited
- Parallel processing is experimental
Verdict
gratia adds plotting, diagnostics, intervals, and tidy outputs to mgcv GAM workflows. It is useful for tidyverse users, with support limits for certain smoothers and documentation still developing.
Facts from gratia's own pages
- Additional capability
- The changelog describes experimental parallel processing support for smooth_estimates() and basis() through purrr, with a current R session configured using mirai::daemons(). · gavinsimpson.github.io, 11 Oct 2026
- Audience
- The overview describes gratia as helping people work with GAMs in the tidyverse, where this can otherwise be tedious or difficult without understanding GAMs and mgcv model objects. · gavinsimpson.github.io, 11 Oct 2026
- Bayesian analysis
- Yes · gavinsimpson.github.io, 24 Sept 2026
- Compatibility limit
- The overview says specialist smoothers with bases mrf, sw, and sf are not currently supported. · gavinsimpson.github.io, 11 Oct 2026
- Confidence intervals
- gratia provides pointwise and simultaneous intervals for estimated smooths. · gavinsimpson.github.io, 11 Oct 2026
- Deployment
- desktop · gavinsimpson.github.io, 24 Sept 2026
- Derivatives
- The derivatives() function estimates derivatives of fitted smooths using finite differences. · gavinsimpson.github.io, 11 Oct 2026
- Development
- The project describes gratia as under active development. · gavinsimpson.github.io, 11 Oct 2026
- Diagnostics
- appraise() provides diagnostic plots for supported GAM, GLM, and linear model fits. · gavinsimpson.github.io, 11 Oct 2026
- Documentation
- The getting-started guide says documentation is an area currently lacking and points users to package help pages and examples. · gavinsimpson.github.io, 11 Oct 2026
- Free plan
- Yes · gavinsimpson.github.io, 24 Sept 2026
- Installation
- The package is available from CRAN with install.packages("gratia"), and the site also documents installation from GitHub and rOpenSci's R Universe. · gavinsimpson.github.io, 11 Oct 2026
- Install options
- The package page lists installation from CRAN, GitHub, and rOpenSci's R Universe service. · gavinsimpson.github.io, 11 Oct 2026
- Integrations
- gratia works with GAMs fitted using mgcv and provides ggplot2-based graphics and tidyverse-compatible representations of estimated smooths. · gavinsimpson.github.io, 11 Oct 2026
- Intended users
- The package is designed to help people working with GAMs in the tidyverse. · gavinsimpson.github.io, 11 Oct 2026
- License
- The project identifies its license as MIT. · gavinsimpson.github.io, 11 Oct 2026
- Maintainer
- The package site names Gavin L. Simpson as author, maintainer, and copyright holder. · gavinsimpson.github.io, 11 Oct 2026
- Models
- It provides graphics and utility functions for GAMs fitted using the mgcv package. · gavinsimpson.github.io, 11 Oct 2026
- Plotting
- Its draw() function uses ggplot2 to plot smooth and parametric contributions from a fitted GAM. · gavinsimpson.github.io, 11 Oct 2026
- Purpose
- gratia provides graphics and utility functions for working with generalized additive models fitted using the mgcv R package. · gavinsimpson.github.io, 11 Oct 2026
- Regression models
- Yes · gavinsimpson.github.io, 24 Sept 2026
- Scripting support
- Yes · gavinsimpson.github.io, 24 Sept 2026
- Statistical tests
- Yes · gavinsimpson.github.io, 24 Sept 2026
- Support
- The project links to GitHub to report bugs and provides a contributing guide and code of conduct. · gavinsimpson.github.io, 11 Oct 2026
Where gratia stands on Freedom251
- Statistical Analysis Software#41 of 106