Miscellaneous Useful Functions for Statistics

A series of functions in some way considered useful to the author. These include methods for subsetting tables and generating indices for arrays, conditioning and intervening in probability distributions, generating combinations, fast transformations, and more...

Very Large Numbers in R

Very large numbers in R. Real numbers are held using their natural logarithms, plus a logical flag indicating sign. Functionality for complex numbers is also provided. The package includes a vignette that gives a step-by-step introduction to using S4 methods.

Bayesian Emulation of Computer Programs

Allows one to estimate the output of a computer program, as a function of the input parameters, without actually running it. The computer program is assumed to be a Gaussian process, whose parameters are estimated using Bayesian techniques that give a PDF of expected program output. This PDF is conditional on a training set of runs, each consisting of a point in parameter space and the model output at that point. The emphasis is on complex codes that take weeks or months to run, and that have a large number of undetermined input parameters; many climate prediction models fall into this class. The emulator essentially determines Bayesian posterior estimates of the PDF of the output of a model, conditioned on results from previous runs and a user-specified prior linear model. The package includes functionality to evaluate quadratic forms efficiently.

Tidy Geospatial Networks

Provides a tidy approach to spatial network analysis, in the form of classes and functions that enable a seamless interaction between the network analysis package 'tidygraph' and the spatial analysis package 'sf'.

Create and Explore Geographic Zoning Systems

Functions, documentation and example data to help divide geographic space into discrete polygons (zones). The package supports new zoning systems that are documented in the accompanying paper, "ClockBoard: A zoning system for urban analysis", by Lovelace et al. (2022) . The functions are motivated by research into the merits of different zoning systems (Openshaw, 1977) . A flexible ClockBoard zoning system is provided, which breaks-up space by concentric rings and radial lines emanating from a central point. By default, the diameter of the rings grow according to the triangular number sequence (Ross & Knott, 2019) with the first 4 doughnuts (or annuli) measuring 1, 3, 6, and 10 km wide. These annuli are subdivided into equal segments (12 by default), creating the visual impression of a dartboard. Zones are labelled according to distance to the centre and angular distance from North, creating a simple geographic zoning and labelling system useful for visualising geographic phenomena with a clearly demarcated central location such as cities.

Methods for Changepoint Detection

Implements various mainstream and specialised changepoint methods for finding single and multiple changepoints within data. Many popular non-parametric and frequentist methods are included. The cpt.mean(), cpt.var(), cpt.meanvar() functions should be your first point of call.

Create, Read, Write, and Work with 'iCalendar' Files, Calendars and Scheduling Data

Provides function to create, read, write, and work with 'iCalendar' files (which typically have '.ics' or '.ical' extensions), and the scheduling data, calendars and timelines of people, organisations and other entities that they represent. 'iCalendar' is an open standard for exchanging calendar and scheduling information between users and computers, described at < https://icalendar.org/>.

Import 'OpenStreetMap' Data as Simple Features or Spatial Objects

Download and import of 'OpenStreetMap' ('OSM') data as 'sf' or 'sp' objects. 'OSM' data are extracted from the 'Overpass' web server (< https://overpass-api.de/>) and processed with very fast 'C++' routines for return to 'R'.

Planning and Analysing Survival Studies under Non-Proportional Hazards

Piecewise constant hazard functions are used to flexibly model survival distributions with non-proportional hazards and to simulate data from the specified distributions. A function to calculate weighted log-rank tests for the comparison of two hazard functions is included. Also, a function to calculate a test using the maximum of a set of test statistics from weighted log-rank tests (MaxCombo test) is provided. This test utilizes the asymptotic multivariate normal joint distribution of the separate test statistics. The correlation is estimated from the data. These methods are described in Ristl et al. (2021) . Finally, a function is provided for the estimation and inferential statistics of various parameters that quantify the difference between two survival curves. Eligible parameters are differences in survival probabilities, log survival probabilities, complementary log log (cloglog) transformed survival probabilities, quantiles of the survival functions, log transformed quantiles, restricted mean survival times, as well as an average hazard ratio, the Cox model score statistic (logrank statistic), and the Cox-model hazard ratio. Adjustments for multiple testing and simultaneous confidence intervals are calculated using a multivariate normal approximation to the set of selected parameters.

Flexible Framework for Developing Spatial Interaction Models

Develop spatial interaction models (SIMs). SIMs predict the amount of interaction, for example number of trips per day, between geographic entities representing trip origins and destinations. Contains functions for creating origin-destination datasets from geographic input datasets and calculating movement between origin-destination pairs with constrained, production-constrained, and attraction-constrained models (Wilson 1979) .