View source: R/simulate_antecedent_conditions.R
simulate_antecedent_conditions | R Documentation |
Simulate heterogenous pattern
simulate_antecedent_conditions(x, i, j, nsim, heterogenous = FALSE, ...)
x |
ppp |
i |
Mark of points that are randomized. |
j |
Mark of points that do not change. |
nsim |
Number of patterns to simulate. |
heterogenous |
If TRUE, points with the mark i are randomized using a heterogeneous Poisson process. |
... |
Arguments passed to |
Simulate point patterns as null model data for spatstat.explore::envelope()
using
antecedent conditions as null model. x
must be marked point pattern.
Antecedent conditions are suitable as a null model if points of type j may influence
points of type i, but not the other way around (Velazquez et al 2016). One example are
the positions of seedlings that may be influenced by the position of mature trees.
Returns a list
with ppp
objects.
list
Velázquez, E., Martínez, I., Getzin, S., Moloney, K.A., Wiegand, T., 2016. An evaluation of the state of spatial point pattern analysis in ecology. Ecography 39, 1–14. <https://doi.org/10.1111/ecog.01579>
Wiegand, T., Moloney, K.A., 2014. Handbook of spatial point-pattern analysis in ecology. Chapman and Hall/CRC Press, Boca Raton, USA. <isbn:978-1-4200-8254-8>
envelope
set.seed(42) pattern_a <- spatstat.random::runifpoint(n = 20) spatstat.geom::marks(pattern_a) <- "a" pattern_b <- spatstat.random::runifpoint(n = 100) spatstat.geom::marks(pattern_b) <- "b" pattern <- spatstat.geom::superimpose(pattern_a, pattern_b) null_model <- simulate_antecedent_conditions(x = pattern, i = "b", j = "a", nsim = 19) spatstat.explore::envelope(Y = pattern, fun = spatstat.explore::pcf, nsim = 19, simulate = null_model)
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