Add ESS extensions

[malcolmbarrett]

No description provided.

[Copilot]

Pull Request Overview

This PR adds Effective Sample Size (ESS) extensions to the halfmoon package, including a new check_ess() function for computing ESS metrics and a plot_ess() function for visualizing them. The PR extends the package's balance diagnostics functionality to help users assess weight variability and potential instability in weighted estimates.

• Added check_ess() function to compute effective sample size for different weighting schemes
• Added plot_ess() function to create bar plot visualizations of ESS values
• Enhanced ess() function to handle missing values with na.rm parameter

Reviewed Changes

Copilot reviewed 31 out of 50 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
R/check_ess.R	New function to compute ESS metrics with optional grouping support
R/plot_ess.R	New function to create bar chart visualizations of ESS values
R/ess.R	Enhanced existing ESS function to handle NA values
tests/testthat/test-check_ess.R	Comprehensive test suite for the new check_ess function
tests/testthat/test-plot_ess.R	Test suite for the plot_ess visualization function
man/*.Rd	Documentation files for the new functions and updated cross-references
NAMESPACE	Export declarations for the new functions
DESCRIPTION	Added scales dependency for plot formatting

Comments suppressed due to low confidence (1)

tests/testthat/test-plot_ess.R:128

• The snapshot tests use expect_doppelganger() which suggests visual regression testing, but this function is not commonly available in standard testthat. Ensure this function is properly available in your testing environment or consider using standard plot testing approaches.

test_that("plot_ess snapshot tests", {