Release v0.2-0 · hturner/PlackettLuce

New Features

Add vignette.
Add data sets pudding, nascar and beans.
Add pltree() function for use with partykit::mob(). Requires new objects of type "grouped_rankings" that add a grouping index to a "rankings" object and store other derived objects used by PlackettLuce. Methods to print, plot and predict Plackett-Luce trees are provided.
Add connectivity() function to check connectivity of a network given adjacency matrix. New adjacency() function computes adjacency matrix without creating edgelist, so remove as.edgelist generic and method for `"PlackettLuce" objects.
Add as.data.frame methods so that rankings and grouped rankings can be added to model frames.
Add format methods for rankings and grouped_rankings, for pretty printing.
Add [ methods for rankings and grouped_rankings, to create valid rankings from selected rankings and/or items.
Add method argument to offer choices of iterative scaling (default), or direct maximisation of the likelihood via BFGS or L-BFGS.
Add itempar method for "PlackettLuce" objects to obtain different parameterizations of the worth parameters.
Add read.soc function to read Strict Orders - Complete List (.soc) files from http://www.preflib.org.

Old behaviour should be reproducible with arguments

npseudo = 0, steffensen = 0, start = c(rep(1/N, N), rep(0.1, D))

where N is number of items and D is maximum order of ties.

Implement pseudo-data approach - now used by default.
Improve starting values for ability parameters
Add Steffensen acceleration to iterative scaling algorithm
Dropped ref argument from PlackettLuce; should be specified instead when calling coef, summary, vcov or itempar.
qvcalc generic now imported from qvcalc

Refactor code to speed up model fitting and computation of fitted values and vcov.
Implement ranking weights and starting values in PlackettLuce.
Add package tests
Add log argument to coef so that worth parameters (probability of coming first in strict ranking of all items) can be obtained easily.