splitting scientific names into genus, species, and sub

I have a list of scientific names in a data set. I would like
to split the names into genus, species and subspecies.
Not all names include a subspecies.  Could someone show me how
to do this?

My example code is:
a <- matrix(c('genusA speciesA', 10,   
              'genusB speciesAA', 20,   
              'genusC speciesAAA subspeciesA', 15, 
              'genusC speciesAAA subspeciesB', 25), nrow=4, byrow=TRUE)
aa <- data.frame(a)
colnames(aa) <- c('species', 'counts')
aa

# The code returns
                                   species  counts
1                     genusA speciesA     10
2                    genusB speciesAA     20
3 genusC speciesAAA subspeciesA     15
4 genusC speciesAAA subspeciesB     25

# I would like there to be 4 columns as below
genus  species    subspecies    counts
genusA speciesA   no.subspecies   10
genusB speciesAA  no.subspecies   20
genusC speciesAAA subspeciesA     15
genusC speciesAAA subspeciesB     25

I have tried using 'strsplit', but cannot get the desired result. 
Thank you for any help with this.

Mark Miller
Gainesville, Florida

The following seems to work for your example. However, others
can probably propose a less clumsy version (but at least this
one breaks it down into its elements):

a <- matrix(c('genusA speciesA', 10,
              'genusB speciesAA', 20,   
              'genusC speciesAAA subspeciesA', 15, 
              'genusC speciesAAA subspeciesB', 25), nrow=4, byrow=TRUE)

a
#      [,1]                            [,2]
# [1,] "genusA speciesA"               "10"
# [2,] "genusB speciesAA"              "20"
# [3,] "genusC speciesAAA subspeciesA" "15"
# [4,] "genusC speciesAAA subspeciesB" "25"

A <- NULL
for( i in (1:nrow(a))){
  Names <- unlist(strsplit(a[i,1],"[ ]+"))
  if(length(Names)==2) Names <- c(Names,"no.subspecies")
  A <- rbind(A,c(Names,a[i,2]))
}
colnames(A) <- c("Genus","Species","Subspecies","Count")
A <- as.data.frame(A)
A$Count <- as.numeric(A$Count)

A
#    Genus    Species    Subspecies Count
# 1 genusA   speciesA no.subspecies     1
# 2 genusB  speciesAA no.subspecies     3
# 3 genusC speciesAAA   subspeciesA     2
# 4 genusC speciesAAA   subspeciesB     4

Hoping this helps!
Ted.


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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 04-Nov-09                                       Time: 21:37:03
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