adehabitat: Number of categories of each habitat
Hello Roy,
Apologies for asking such a simple question, but I have been having
problems obtaining a simple summary of the habitat classes in a
categorical (factor) asc map in the adehabitat library. It has been
created from overlaying an mcp polygon as follows:
# Importation of asc files: factor e.g vegetation map
(vegm <- paste("Y:/Map Import/veg05_7.asc", sep = "/")) # veg05_7 is a vegetation map with 10 classes
(vegt <- paste("Y:/Map Import/veg05_2.txt", sep = "/")) # veg05 is a table with the names of the 10 classes
veg <- import.asc(vegm, lev = vegt, type = "factor")
# A Script to compute Homerange using Minimum Concex Polygon(MCP)
roans<-read.csv("Y:/PhD Data/Data Analysis/Roan Data Analysis/Rawdata/NTO_G.csv") # Load the data
xy<-roans[,c("X","Y")] # combine columns X & Y into a new column labelled xy
id<-roans$Group # Allocate label id to Group column
hrtg<-mcp(xy,id,percent=95) # Compute the homerange MCP
## Converts the home range to raster
hrrast <- hr.rast(hrtg, veg)
## for each relocation, finds the values of the variables in x
mcpveg = setmask(veg, hrrast)
This line is incorrect (hrrast is an object of class "kasc", it should be of class "asc"), and useless since you redefine mcpveg below.
hrrast2 = getkasc(hrrast, "Nyatoto Group") mcpveg = setmask(veg, hrrast2)
At this point mcpveg is a *matrix* of class "asc".
The asc map, mcpveg, produced by the final setmask function contains just the vegetation types within the MCP. This map displays correctly. However, I'm unclear on how to obtain a numerical summary of the number of cells of each vegetation type, or percentage of each vegetation type, within the MCP. Typing: summary(mcpveg) gives hundreds of columns, relating to the geographic structure of the asc map.
Because mcpveg is a matrix, calling summary on it computes one summary per column of the matrix (which is not what you want). You should first convert it to vector. Try: ta <- table(as.vector(mcpveg)) names(ta) <- levels(mcpveg)[as.numeric(names(ta))] ta HTH, Cl?ment Calenge
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