marksum {ecespa} | R Documentation |
An exploratory data analysis technique for marked point patterns. The marked point pattern is mapped to a random field for visual inspection.
marksum(mippp, R = 10, nx = 30, ny = 30) marksum.plot(mimarksum, what="normalized", gris=FALSE, contour=FALSE, interpol=TRUE, leip=100, main="", ...)
mippp |
A marked point pattern. An object with the ppp format of spatstat. |
R |
Radius. The distance argument r at which the mark-sum measure should be computed |
nx |
Grid density (for estimation) in the x-side. |
ny |
Grid density (for estimation) in the y-side. |
mimarksum |
Result of applying marksum to a point pattern. |
what |
What to plot. One of "marksum" (raw mark sum measure), "point" (point sum measure) or "normalized" (normalized sum measure). |
gris |
Logical; if "TRUE" display map in grey levels. |
contour |
Logical; if "TRUE" add contour to map. |
interpol |
Logical; if "TRUE" display interpolated results (with function interp of akima). |
leip |
Number of points in the side of the grid of points to interpolate the results. |
main |
Text or expression to be displayed as a title in the map. |
... |
Additional parametrs to contour . |
Penttinen (2006) defines the mark-sum measure as a smoothed summary measuring locally the contribution of points and marks. For any fixed location x within the observational window and a distance R, the mark-sum measure S[R](x) equals the sum of the marks of the points within the circle of radius R with centre in x. The point-sum measure I[R](x) is defined by him as the sum of points within the circle of radius R with centre in x, and describes the contribution of points locally near x. The normalized mark-sum measure describes the contribution of marks near x and is defined (Penttinen, 2006) as
S.normalized[R](x) = S[R](x)/I[R](x)
This implementation of marksum
estimates the mark-sum and the point-sum measures in a grid of points whose density is defined by nx
and
ny
.
marksum
gives a list with the following elements:
normalized |
Normalized mark-sum measure estimated in the grid points. |
marksum |
Raw mark-sum measure estimated in the grid points. |
pointsum |
Point-sum measure estimated in the grid points. |
minus |
Point-sum of the grid points. For advanced use only. |
grid |
Grid of points. |
nx |
Density of the estimating grid in the x-side. |
ny |
Density of the estimating grid in the x-side. |
R |
Radius. The distance argument r at which the mark-sum measure has been computed. |
window |
Window of the point pattern. |
marksum.plot
plots the selected mark-sum measure.
Marcelino de la Cruz Rot marcelino.delacruz@upm.es
Penttinen, A. 2006. Statistics for Marked Point Patterns. In The Yearbook of the Finnish Statistical Society, pp. 70-91.
getis
, related to the point-sum measure, and markstats
for designing different implementations
## Not run: data(seedlings1) seed.m <- marksum(seedlings1, R=20) marksum.plot(seed.m, what="marksum") # raw mark-sum measure marksum.plot(seed.m, what="pointsum") # point sum measure marksum.plot(seed.m, what="normalized") # normalized mark-sum measure ## End(Not run)