[R-sig-Geo] Filtering a set of points in a "ppp" object by distance using marks

[ASANTOS]

Dear R-Sig-Geo Members,

I'd like to find any way to filtering a set of points in a "ppp" object by minimum distance just only between different marks. In my example:

#Package
library(spatstat)

#Point process example - ants
data(ants)
ants.ppp<-ppp(x=ants$x,y=ants$y,marks=rep("antNests",length(ants$x)),window=Window(ants))


# Create a artificial point pattern - termites
termites <- rpoispp(0.0005, win=Window(ants))
termites.ppp<-ppp(x=termites$x,y=termites$y,marks=rep("termiNests",length(termites$x)),window=Window(ants))


#Join ants.ppp and termites.ppp
insects.ppp<-superimpose(ants.ppp,termites.ppp)


#If I try to use subset function:

subset(insects.ppp, pairdist(insects.ppp) > 20 & marks=="termiNests")

#Marked planar point pattern: 223 points #marks are of storage type 
�character� #window: polygonal boundary #enclosing rectangle: [-25, 803] 
x [-49, 717] units (one unit = 0.5 feet) #Warning message: #In ppp(X[, 
1], X[, 2], window = win, marks = marx, check = check) : # 70751 out of 
70974 points had NA or NaN coordinate values, and were discarded

Not the desirable result yet, because I'd like to calculate just only the > 20 "termiNests" to "antNests" marks and not the "termiNests" with "termiNests" too.

Please any ideas?

Thanks in advanced,

-- 
Alexandre dos Santos
Geotechnologies and Spatial Statistics applied to Forest Entomology
Instituto Federal de Mato Grosso (IFMT) - Campus Caceres
Caixa Postal 244 (PO Box)
Avenida dos Ramires, s/n - Vila Real
Caceres - MT - CEP 78201-380 (ZIP code)
Phone: (+55) 65 99686-6970 / (+55) 65 3221-2674
Lattes CV: http://lattes.cnpq.br/1360403201088680
OrcID: orcid.org/0000-0001-8232-6722
ResearchGate: www.researchgate.net/profile/Alexandre_Santos10
Publons: https://publons.com/researcher/3085587/alexandre-dos-santos/
--


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