movecost 3.0.0

A ground-up redesign of the package’s architecture, while retaining all the analytical capabilities (and the 26 cost functions) of the previous releases. The baseline for the comparisons below is the last version published on CRAN, movecost 2.2.

New architecture: compute once, reuse everywhere

• New mc_surface() builds the cost graph once; every analysis function (mc_accum(), mc_paths(), mc_corridor(), mc_boundary(), mc_alloc(), mc_network(), mc_rank()) reuses it. In the 2.x series each call to movecost(), movecorr(), movealloc(), movebound(), movenetw(), moverank() rebuilt the conductance matrix from scratch (an n-location network implied O(n) redundant constructions); that redundancy is gone.
• Multi-origin computations (allocation, boundaries, cost matrices) are served by single batched Dijkstra queries (igraph).

Modern spatial stack

• The computational core now rests on terra + sf + igraph. The retired or maintenance-mode dependencies of the 2.x series (raster, sp, gdistance, chron, Matrix as a direct import, elevatr as a hard dependency) are gone; elevatr is now an optional (Suggested) dependency used only by mc_dtm().
• Legacy sp/raster inputs are still accepted everywhere and coerced internally, so existing data files keep working.
• Sample datasets are now shipped as standard GIS files (GeoTIFF/GeoPackage, read via mc_volc(), mc_malta_dtm(), mc_volc_loc(), mc_destin_loc(), mc_springs(), mc_etna_start(), mc_etna_end(), mc_etna_boundary()), removing the last data-level dependency on raster/sp.

Decoupled, ggplot2-based visualisation

• Computation and visualisation are fully separated: every result object is plotted on demand via plot() / autoplot() methods returning ggplot objects, which can be stored, customised with standard ggplot2 syntax, and re-drawn at will - without re-running any analysis (in 2.x, obtaining a new visualisation required re-running the computation).
• Styling is exposed through plot arguments: isoline colour and width (iso.col, default white, iso.lwd), least-cost-path width (lcp.lwd), and label sizes (cex.breaks for isoline labels, cex.lcp.lab for destination labels, cex.node.lab / cex.origin.lab for network and allocation labels).
• Network nodes and allocation origins are labelled with their indices by default (node.lab, origin.lab), matching cost.matrix and the allocation zones respectively, reproducing the 2.x numbering.

Corrected cost-function errors (results change because 2.2 was wrong)

These are fixes to mistakes present in the last CRAN release (movecost 2.2), verified against the source publications. Analyses using the affected functions will give different (correct) results.

• Kondo-Seino (ks), Marin Arroyo (ma), and Pandolf-with-correction (pcf): the slope-sign tests are now applied to the signed slope, as the original publications intend. In 2.2 those tests were applied to the absolute slope, so the downhill branches (the gentler ks decay, the gentler ma divisor, the Yokota et al. downhill correction in pcf) could never be selected. Results on downhill gradients therefore differ - correctly - from 2.2.
• Pandolf-family functions (p, vl): the terrain factor N is now applied once, as the coefficient eta of Pandolf et al. (1977), multiplying the velocity-dependent term; 2.2 additionally multiplied the whole expression by N, counting terrain twice and inflating the basal-metabolism terms. With the default N = 1 results are unchanged; for N != 1 they differ (correctly) from 2.2.
• Hare metabolic cost function (funct = "h"): the 2.2 code contained a double-reciprocal that reduced algebraically to 1 / ((48 + 30 * v) * N) rather than the intended 1 / ((48 + 30 / v) * N), where v is the cell-by-cell on-path Tobler walking speed. The corrected formula reproduces the body-mass-anchored approximation of Ralston (1958) cited by Hare (2004), agreeing with it to within ~5% across 2-6 km/h (the 2.2 code diverged by a factor of three or more). The plotted cost-unit label is corrected from “cal/km” to “kcal/km” to match.
• Metabolic functions with dynamic speed (funct = "vl", "p", "pcf", "a" with V = 0): in 2.2 the value substituted for the velocity was the reciprocal of Tobler’s on-path speed rather than the speed itself, mis-stating the metabolic rate (about half the canonical value on flat ground, a multiple on steep terrain). Version 3.0 substitutes Tobler’s speed in m/s directly. Results obtained with V = 0 therefore differ from 2.2; analyses using a non-zero V (including the default 1.2) are unaffected.

Design changes and enhancements (method improved or generalised)

These are deliberate refinements of how a result is produced. Where 2.x followed a specific published method, the 2.x behaviour is preserved as the default and the refinement is offered as an option.

• Least-cost corridors (mc_corridor()): the classic definition of the 2.x series, the sum of two accumulated cost surfaces spread outward from the two locations after Mitchell (2012), is kept as the default (method = "reach"), is symmetric, and reproduces 2.x. A new method = "through" option adds a directional alternative, cost(A->x) + cost(x->B) (the second term on the reversed graph), whose minimum equals the A-to-B least-cost-path cost; it is intended for one-way journey analysis under anisotropic cost functions. The two coincide for isotropic functions. For the two-location case the least-cost paths A-to-B and B-to-A are computed, returned, and overlaid on the plot, as in 2.x.
• Cost-limit boundaries (mc_boundary()): the boundary is now obtained by polygonising the reachable area directly (cells at or below the limit), yielding closed polygons with exact area and perimeter; 2.x derived it from contour lines of the accumulated surface. The result is a more rigorous, measurable catchment polygon.
• Ranked sub-optimal paths (mc_rank()): same iterative-penalisation idea as 2.x’s moverank(), but operating directly on the graph edge weights, so any number of ranks can be requested (2.x was capped at 6) and the avoidance strength is exposed through a tunable penalty parameter.
• Irregular DTMs: NoData cells are excluded from the cost graph by construction, so accumulated costs and paths never cross them and the irregular.dtm workaround (and parameter) of 2.x is no longer needed.
• Least-cost networks (mc_network()): the path-density rasters are computed exactly from the graph vertices of each path (no rasterisation approximation), and the network nodes are numbered on the plot and in the returned nodes object, matching the row/column indices of cost.matrix, as in 2.x.
• Sample data: the bundled datasets carry explicit EPSG codes (e.g. Etna EPSG:23032, verified to fall on Mount Etna; volc EPSG:27200; Malta EPSG:23033), so their CRS is encoded identically across the GeoTIFF and GeoPackage files.

Other improvements

• Exports now use GeoPackage instead of ESRI shapefile (no 10-character field-name truncation); mc_export() handles every result class.
• mc_save()/mc_load() provide reliable on-disk persistence of result objects (SpatRaster components cannot survive a bare saveRDS()).
• mc_cost_functions() returns the full annotated registry of the 26 cost functions (codes, families, units, parameter usage), which is also the single internal source of cost-function definitions (in 2.x the definitions were duplicated across functions).
• Walking-time formatting no longer depends on chron (internal HH:MM:SS formatter).
• Informative validation errors: geographic-CRS rasters, CRS mismatches, locations outside the DTM or on NoData cells, unknown cost-function codes.
• Comprehensive testthat suite with analytic and consistency checks, plus independent validation materials in inst/validation/.

API correspondence with the 2.x series

movecost 2.2

• Added the topo.dist parameter to movecost(): when TRUE, accumulated cost uses topographic (surface) distance rather than planar distance, accounting for the extra distance over sloped terrain (surface = planar * sqrt(1 + slope^2); about +4.4% on a 30% slope, +11.8% on a 50% slope). Particularly recommended for time-based hiking functions; to be used with caution for metabolic functions, which were derived against planar distance.
• Added a documentation section explaining the methodology and its appropriateness per cost-function type.
• Propagated topo.dist to all wrapper functions (movealloc(), movebound(), movecomp(), movecorr(), movenetw(), moverank()); the default FALSE preserves backward compatibility.

movecost 2.1

• Resolved lost-braces issues in \itemize sections across several Rd files.
• Corrected the create_barrier_cs documentation (missing fields argument in \usage).
• Minor help-documentation amendments.

movecost 2.0

• Integrated create_barrier_cs (from an earlier version of the ‘leastcostpath’ package) as an internal function; dependency on ‘leastcostpath’ dropped; dependency on ‘Matrix’ added.
• Minor fixes and documentation amendments.

movecost 1.9

• Added the netw.type parameter to movenetw().
• Documentation amendments for the origin/destination parameters.
• Dropped the dependence on ‘rgdal’, ‘maptools’, ‘rgeos’, ‘spatstat.geom’.

movecost 1.8

• Added the moverank() function.
• Added the facility (via irregular.dtm) to prevent LCPs crossing NoData (sea) areas.
• Added length/cost distribution charts to movecomp() (via add.chart); the returned LCPs now store the cost.
• Fixed the closest-location calculation in movenetw().
• Added the Tripcevich hiking function; added the malta_dtm_40 and springs datasets.
• Replaced the hillshade with a slopeshade raster in all rendered plots.
• Documentation updates.

movecost 1.7

• Added the Hare metabolic and Eastman abstract cost functions (25 functions total).
• Added barrier handling to all functions except movealloc().
• movecost() returns the conductance transitional layer (used to optimise movenetw()).
• movenetw() also computes LCP networks between neighbouring locations and returns a pairwise cost matrix; internal optimisation (~3x faster than 1.6); oneplot dropped; export fix.
• Documentation fixes; vignette link added throughout.

movecost 1.6

• Fixed a projection issue in the in-built volc dataset.
• Internal optimisations in movenetw().
• Documentation improvements.

movecost 1.5

• movenetw(): fixed exported-GeoTiff naming; documentation tweaks.
• Added the volc RasterLayer to the sample datasets.

movecost 1.4

• Added movecomp() and movenetw().
• Added cost functions: Minetti et al., Marin Arroyo, Ardigo et al., Pandolf et al. with correction factor (23 functions total).
• Added perimeter/area output to movebound().

movecost 1.3

• Added movealloc().
• Added the Kondo-Seino modified Tobler function.
• Pandolf and Van Leusen functions can derive walking speed from the Tobler function by setting V = 0.
• movecorr() plots point locations on top of the multi-origin corridor.

movecost 1.2

• Added movebound().
• Overlaid a hillshade on the rendered surfaces (transparency via transp).
• LCP destination labels show time in sexagesimal form; added the cost_hms variable to the returned destination layer; that layer is now exportable.
• Minor plot and documentation amendments.

movecost 1.1

• Fixed the Bellavia cost function (introduced in 1.0).
• Extended the terrain factor (N) to almost all cost functions.
• Plot and documentation improvements.

movecost 1.0

• Added the option to compute and plot LCPs back to the origin.
• Added the Garmy et al., Rees, and Bellavia cost functions (18 total).
• Documentation updates with references.

movecost 0.9

• movecorr() can produce a corridor between two locations or among multiple locations; added the 0-1 rescaling option.
• Added the ‘cognitive slope’ option to movecost() and movecorr().

movecost 0.8

• Fixed a bug preventing the downloaded DTM being returned by movecorr().
• Added point-label customisation and optional export of DTM, LCPs, and accumulated surfaces to movecorr(); the accumulated rasters are now returned.
• movecost() now returns (without plotting) the cost surface.
• Minor optimisations and documentation amendments.

movecost 0.7

• Added movecorr(); added the graph.out option to movecost(); renamed the Marquez-Perez function code from mt to mp.

movecost 0.6

• Added online elevation-data download (via ‘elevatr’) when no DTM is supplied; added three sample datasets; documentation updated.

movecost 0.5

• Added the Irmischer-Clarke female functions; renamed the parameters to icmonp, icmoffp, icfonp, icfoffp; documentation layout improvements.

movecost 0.4

• Added the move parameter (number of directions in which cells connect).

movecost 0.3

• Added the Llobera-Sluckin metabolic function and the Alberti modified Tobler function for animal foraging excursions.

movecost 0.2

• Cost calculation now follows van Etten (2017), computing slope as the altitudinal difference between cells divided by the distance between cell centres (rise over run, direction-dependent), making the cost functions truly anisotropic. Output colour ramp changed.

movecost 0.1

• First release to CRAN.