[R-sig-Geo] raster: extract() based in a pixel value

[ASANTOS]

Dear R-sig-geo Members,

I'd like to use de extract() function using the raster package for 
calculate a proportion of pixel with "1"s values inside a buffer given 
some coordinates in a raster. I try to create a function for this 
without success, in my hypothetical example:

#Package
library(raster)

# Create a raster
ras <- raster(ncol=1000, nrow=1000)
set.seed(0)
values(ras) <- runif(ncell(ras))
values(ras)[values(ras) > 0.5] = 1
values(ras)[values(ras) < 0.5] = NA

# Create some coordinates
pts<-sampleRandom(ras, size=30, xy=TRUE)
pts.df<-as.data.frame(pts)
pts.df$area<-rnorm(30, mean=10)## Here just for create a artificial 
covariate without any direct implication in my question

#Function for extract proportion of 1s values
percentual_1s<- function(x,...) {
 � leng1<-length(values(x) ==1) # length of 1s pixels values
 � lengtotal<-length(x) # total length of pixels inside buffer
 � perc<-(leng1/lengtotal)*100
 � return(perc)
}

# Extract the desirable proportion in a circular 100000 units buffer
cent_max <- extract(ras, # raster layer
 ��� cbind(pts.df$x,pts.df$y),��� # SPDF with centroids for buffer
 ��� buffer = 100000,������������ # buffer size
 ��� fun=percentual_1s,���������� # what to value to extract
 ��� df=TRUE)


Here doesn't work, despite the code look like Ok. My perfect output is:

#������� x����� y layer����� area�� percentual_1s
#1 -109.26 -43.65���� 1 10.349010�� 23.15
#2�� 93.42 -87.21���� 1� 9.861920�� 45.18
#3�� 57.06� 86.85���� 1� 8.642071�� 74.32
#4 -109.98 -45.63���� 1 10.376485�� 11.56
#5� -92.34� 37.89���� 1 10.375138�� 56.89
#6�� 19.62� 21.51���� 1� 8.963949�� 88.15


Please any ideas or any another package that help in this operation?

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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