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Gallery of code for np, npRmpi, and crs

This site is meant to help you get to working code quickly. The sidebar is now organized by task rather than by old document names, and the search box should find function names such as npreg, npudens, crs, and npRmpi.init.

This gallery complements the package help pages, examples, and vignettes. The aim is simple: make it easy to see what each package is for, copy a small working example, and then move on to longer scripts only if you need them.

If you are new to these packages, start with Choose a Package. If you want runnable code immediately, go to Quickstarts. If you already know the method you want, go directly to Kernel Methods, MPI and Large Data, Splines, or Worked Examples.

Cross-validated spline illustration

This website is linked from my academic site and is intended as a practical working companion, not as a substitute for the package manuals or the underlying papers.

NoteCurrent plotting interface

This Gallery now tracks the current np / npRmpi 0.70-2 plotting interface on CRAN as of Friday, May 15, 2026.

The redesigned examples use public controls such as errors, bootstrap, band, data_rug, data_overlay, and other snake_case option names. Older plotting code may need small argument-name updates once the new release is installed.

Recent Extensions

• Local polynomial workflows: np and npRmpi now support local polynomial capability across the conditional family, with joint selection of polynomial degrees and bandwidths for mixed data, gradient support throughout the conditional estimators, and derivative estimation of arbitrarily high order, limited only by the selected polynomial degree whether set manually or chosen automatically for the underlying smoothness class.
• Bounded-support and proper conditional density/distribution methods: conditional density and distribution workflows now include bounded-kernel routes for known bounds and practical unknown-bound settings, plus proper = TRUE for proper local-polynomial conditional density/distribution estimates when degree exceeds zero.
• Conditional quantile regression: npqreg now has a direct formula interface, automatic npcdistbw() bandwidth selection when bws is omitted, vector tau support, plot(..., tau = ...) reuse of existing bandwidths, conditional-quantile gradients and standard errors, and nomad = TRUE pass-through for local-polynomial degree-and-bandwidth search.
• Conditional mode classification: npconmode is now a first-class high-level estimator, with direct formula/data/newdata workflows, automatic npcdensbw() bandwidth selection when bws is omitted, conditional-density search controls including nomad = TRUE, mirrored degree/search metadata in returned objects and summaries, properized fitted class probabilities for non-local-constant routes before selecting the modal outcome, and level-specific class-probability effects.
• Copula estimation: npcopula is now a first-class high-level estimator too, with a direct formula interface, automatic npudistbw() or npudensbw() selection when bws is omitted, automatic two-dimensional probability-grid construction for the default grid route, and easy reuse of the selected bandwidth object when you want a custom u grid or copula-density target.
• Hat-matrix and operator helpers: npreghat, npindexhat, npplreghat, and npscoefhat now provide one-call operator routes that simplify constrained nonparametric and semiparametric estimation by replacing much of the older manual hat-matrix construction and solve-based setup, while npudenshat, npudisthat, npcdenshat, and npcdisthat extend the same streamlined operator style to the density/distribution family.
• Variability bounds on plots: Bonferroni and simultaneous bounds are new additions to the plotting surface, while band = "all" now presents those together with the traditional pointwise bounds.
• Interactive plotting surfaces: renderer = "rgl" now supports interactive 3D rotation/zoom when rgl is installed, while data_rug and data_overlay control rugs and observed-data overlays on supported routes.
• MPI operational routes: npRmpi is no longer limited to the older profile/manual-broadcast interface; current session and attach routes let users work far more directly with np-style code while retaining the profile route when needed.

Choose a Package

Start here if you are deciding between np, npRmpi, and crs, or if you want a quick route to the right tool.

Install and Get Started

Short install notes, a minimal first run, and pointers for what to do next once the packages are installed.

Quickstarts

Small runnable scripts for np, npRmpi, and crs, shown inline so you can copy directly from the page.

Kernel Methods

Core workflows for np, together with a clean route to npRmpi when jobs become larger or more time consuming.

MPI and Large Data

Updated guidance for npRmpi, with session mode now treated as the main interactive path rather than an afterthought.

Worked Examples

Copyable code snippets on the page, plus links to longer scripts when you want the full commented version.

Multivariate Regression

Mixed-data regression, partial plots, and prediction using wage1 as a practical first multivariate example.

FAQ and Troubleshooting

Common questions, support routes, and links to the current canonical sources.

Learn by topic

Kernel Primer

Short conceptual introduction to mixed-data kernels, bandwidth objects, and the basic np workflow.

Density, Distribution, Quantiles

Route to npudens, npudist, npcdens, npcdist, and npqreg workflows.

Semiparametric Models

Partially linear, single-index, and varying-coefficient workflows in one place.

Entropy and Testing

Overview of the entropy-based testing procedures and a small “roll your own” example.

Classification and Modes

Nonparametric classification and conditional-mode workflows, including the birthwt example.

Build With npksum

For users who want to construct custom kernel objects or estimators rather than only use the higher-level wrappers.

Spline Primer

Conceptual introduction to regression splines, knots, basis functions, and how that connects to crs.

Code Catalog

Broader script library across np, npRmpi, and crs, including older scripts and fuller worked examples beyond the first quickstarts.

Need help fast?

FAQ and Troubleshooting

Short answers to the most common “where do I start?” and “why is this happening?” questions.

Data Preparation

Variable classes, factors, ordered variables, formulas, and the data-typing mistakes that most often trip people up.

Runtime and Scaling

What to do when cross-validation, bootstrap, spline search, or large jobs become slow or memory-hungry.

Spline Search and Tuning

Practical crs advice on search size, smoothness, knots, and when to narrow the spline search space.

Notes

• Search should help if you know the function name but not where it lives.
• Quickstarts is the shortest route to a small runnable script.
• The reference page groups functions by task rather than repeating a long handwritten index.
• Additional resources, including books and papers, are collected on Books, Papers, and Citation.

Feedback is welcome. My academic page is experts.mcmaster.ca/display/racinej, and additional materials remain available at jeffreyracine.github.io/research.