pat2dists {apcf} | R Documentation |
Creates n_sim
null models by permutation of the original pattern and
calculates distances between all object of a pattern closer than max_dist
and determines the fractions of the perimeter of buffers with distance
dist
inside the study area (needed for edge correction).
pat2dists(area, pattern, max_dist, n_sim = 199, max_tries = 1e+05, save_patterns = NULL, verbose = FALSE)
area, pattern |
Data source name of study area and pattern (interpretation varies by driver - for some drivers, dsn is a file name, but may also be a folder, or contain the name and access credentials of a database) |
max_dist |
Maximum distance measured in the pattern. Usually smaller than half the diameter of the study area. |
n_sim |
Number of simulated patterns (randomizations) to be generated
for computing the envelope and correcting the biased emperical pcf.
Determines together with |
max_tries |
How often shall a relocation of an object be tried while randomizing the pattern. |
save_patterns |
Shall the simulated patterns be saved as Shapefiles
for debugging/later inspections. Might be a large number of files
(4 * n_sim). Can be |
verbose |
Provide progress information in the console. Roman numerals (x: 10, C: 100, D: 500, M: 1000) indicate the progress of the simulation and 'e' the emperical PCF. |
Null models are created by randomly rotating and randomly placing all objects within the study area without overlap. They are used for correcting the biased pcf and constructing a pointwise critical envelope (cf. Nuske et al. 2009).
Measuring distances between objects and permutation of the pattern is done with GEOS and spatial data are converted to GEOS geometries by GDAL/OGR.
An object of class dists.
Nuske, R.S., Sprauer, S. and Saborowski J. (2009) Adapting the pair-correlation function for analysing the spatial distribution of canopy gaps. Forest Ecology and Management, 259(1), 107-–116. doi: 10.1016/j.foreco.2009.09.050
# it's advised against setting n_sim < 199 ds <- pat2dists(area=system.file("shapes/sim_area.shp", package="apcf"), pattern=system.file("shapes/sim_pat_reg.shp", package="apcf"), max_dist=25, n_sim=3, verbose=TRUE)