Hi everyone,

I am working with the dbFD function of the FD package, and there's something
funny happening with the value of sing.sp in the output.  Basically, I  have
a species-function matrix and a community matrix.  One site in particular
has 6 species, 4 of which have identical functional coding.  I thus expect
nbsp = 6 and sing.sp = 2 for this site.  However, nbsp = sing.sp = 6.  This
confuses me.  I have read the help files and the FD manual and I've googled,
but I remain unenlightened.  (and I checked to be sure that I'm running the
latest version of FD, 1.0-7)

Am I entirely misunderstanding what sing.sp means?  Do I have a coding
problem?  Is this a bug?  Hopefully someone can set me straight.

Here you can see the same problem for a simplified example:

fd <- matrix (c("a","b","c","d", "a","b","c","d",
"b","c","d","a", "c","d","b","a"), byrow = TRUE, nrow=4, ncol=4)
    rownames (fd) <- c("spA", "spB", "spC", "spD") #  species
    colnames (fd) <- c("F1", "F2", "F3", "F4")  # functional categories

fd # note that spA and spB have identical functional coding

comm <- matrix (c(1,0,1,0, 1,0,1,0, 0,1,1,0, 0,1,0,1), nrow=4, ncol=4)
    rownames (comm) <- c("site1", "site2", "site3", "site4")
    colnames (comm) <- c("spA", "spB", "spC", "spD")
comm # note that site 1 has only spA and spB, so I'd expect it to
     # have sing.sp = 0 (no singular species)

require (FD)
ex1 <- dbFD (fd, comm, w.abun = FALSE, corr="cailliez", clust.type="ward")
ex1 # site 1 comes out with sing.sp = 2.  Why is that?

Any insight / advice would be greatly appreciated!

Many thanks,
Sarah
University of Chicago

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