Create Compact Letter Display (CLD) for Statistical Comparisons.
cld: Compact Letter Display for Statistical Comparisons
Simplify your statistical reporting with compact letter displays
The cld package provides an easy and consistent way to create compact letter displays (CLDs) for visualizing results of pairwise statistical comparisons. Groups sharing the same letter are not significantly different from each other — a convention widely used in agricultural, biological, and statistical publications.
Why Use cld?
Key Features:
- 🔄 Universal compatibility - Works with base R, PMCMRplus, rstatix, DescTools, and custom formats
- 🎯 One function -
make_cld()handles all input types automatically - 📊 Publication-ready - Clean, professional statistical grouping labels
- 📝 Informative - Stores metadata (alpha, method, comparison counts)
- 🛠️ Well-tested - Comprehensive unit tests ensure reliability
Installation
Install the stable version from CRAN:
install.packages("cld")
Install the development version from GitHub:
# install.packages("devtools")
devtools::install_github("GegznaV/cld")
Quick Start
The cld package works with various statistical test outputs. Here’s a simple example:
library(cld)
# Run a pairwise test
test_result <- pairwise.wilcox.test(chickwts$weight, chickwts$feed, exact = FALSE)
# Generate compact letter display
make_cld(test_result)
#> group cld spaced_cld
#> casein a a__
#> horsebean b _b_
#> linseed bc _bc
#> meatmeal ac a_c
#> soybean c __c
#> sunflower a a__
Interpretation:
- Groups sharing at least one letter are not significantly different (e.g., casein and sunflower both have “a”);
- Groups with no shared letters are significantly different (e.g., horsebean “b” and soybean “c”).
Supported Input Formats
The make_cld() function works seamlessly with:
| Input Type | Example Packages | Function Examples |
|---|---|---|
pairwise.htest | base R | pairwise.t.test(), pairwise.wilcox.test() |
PMCMR / PMCMRplus | PMCMR, PMCMRplus | kwAllPairsConoverTest(), dunnTest() |
data.frame (rstatix) | rstatix | games_howell_test(), tukey_hsd() |
PostHocTest | DescTools | ConoverTest(), DunnettTest() |
matrix | Custom | Symmetric p-value matrices |
data.frame | Custom | Custom comparison data frames |
formula | Custom | Formula interface for data frames |
Learn More
📚 Comprehensive vignettes (also available on package website):
vignette("cld")- Complete introduction with examplesvignette("cld-input-formats")- Detailed examples for all input typesvignette("cld-interpretation-guide")- How to correctly interpret CLDsvignette("cld-advanced-features")- Advanced features and custom parameters
Related Packages
| Package | Purpose | Relationship to cld |
|---|---|---|
| multcompView | CLD algorithm | Used internally by cld |
| rcompanion | Statistical functions | Alternative CLD implementation |
| PMCMRplus | Post-hoc tests | Compatible input for cld |
| rstatix | Tidy statistics | Compatible input for cld |
| DescTools | Statistical tools | Compatible input for cld |
Getting Help
- 📖 Function reference:
?cld::make_cld - 📚 Package website: https://gegznav.github.io/cld/
- 🐛 Report bugs: https://github.com/GegznaV/cld/issues
- 💬 Ask questions: GitHub Discussions
Citation
To cite the cld package in publications:
citation("cld")
License
GPL-3