Covariance-Based Ellipses and Annotation Tools for Ordination Plots
Autoplot method for barrel_ord objects
Add Axis Titles with Method Name and Explained Variance
Summary Statistics for Ordination Objects
Prepare ordination object for barrel plotting
Comprehensive Ordination Visualization Layer
Internal function to get axis labels for vegan ordination objects
Compute coordinates for an ordination ellipse
Compute Ellipse Coordinates for a Single Group
Compute Ellipse Coordinates for All Groups
Extract Group Centroids from Ordination Scores
Extract covariance matrix from ordination scores with optional robust ...
Extract significant environmental vectors from vegan ordination object
Provides tools to visualize ordination results in 'R' by adding covariance-based ellipses, centroids, vectors, and confidence regions to plots created with 'ggplot2'. The package extends the 'vegan' framework and supports Principal Component Analysis (PCA), Redundancy Analysis (RDA), and Non-metric Multidimensional Scaling (NMDS). Ellipses can represent either group dispersion (standard deviation, SD) or centroid precision (standard error, SE), following Wang et al. (2015) <doi:10.1371/journal.pone.0118537>. Robust estimators of covariance are implemented, including the Minimum Covariance Determinant (MCD) method of Hubert et al. (2018) <doi:10.1002/wics.1421>. This approach reduces the influence of outliers. barrel is particularly useful for multivariate ecological datasets, promoting reproducible, publication-quality ordination graphics with minimal effort.