5.2 An alternative practice data set

# Import the file
species <- read.csv(file.path(DATADIR, "species.csv"), header = TRUE, 
                    as.is = c("Scientific_name","Common_name", "Taxon_author"))

# Identify the classes of organism
levels(species$Class)
##  [1] ""                     " "                    "amphibians"          
##  [4] "arachnids"            "birds"                "bivalves"            
##  [7] "blue-green algae"     "branchiopods"         "brown algae"         
## [10] "cartilaginous fishes" "club fungi"           "club mosses"         
## [13] "conifers"             "cycads"               "diatoms"             
## [16] "dinoflagellates"      "euglenoids"           "ferns"               
## [19] "golden-brown algae"   "green algae"          "higher dicots"       
## [22] "hornworts"            "insects"              "lampreys"            
## [25] "liverworts"           "lobe-finned fishes"   "lower dicots"        
## [28] "malacostracans"       "mammals"              "maxillopods"         
## [31] "monocots"             "mosses"               "quillworts"          
## [34] "ray-finned fishes"    "red algae"            "reptiles"            
## [37] "sac fungi"            "slime molds"          "snails"              
## [40] "spike mosses"         "uncertain"            "whisk ferns"         
## [43] "yellow-green algae"
# OR
unique(species$Class)
##  [1] amphibians                                arachnids           
##  [4] birds                bivalves             branchiopods        
##  [7] cartilaginous fishes insects              lampreys            
## [10] lobe-finned fishes   malacostracans       mammals             
## [13] maxillopods          ray-finned fishes    reptiles            
## [16] snails               club fungi           sac fungi           
## [19] uncertain                                 slime molds         
## [22] higher dicots        liverworts           ferns               
## [25] monocots             mosses               lower dicots        
## [28] hornworts            conifers             cycads              
## [31] quillworts           club mosses          whisk ferns         
## [34] spike mosses         red algae            green algae         
## [37] diatoms              blue-green algae     brown algae         
## [40] yellow-green algae   golden-brown algae   euglenoids          
## [43] dinoflagellates     
## 43 Levels:    amphibians arachnids birds bivalves ... yellow-green algae
# Select just the entries for a single class
species.class <- species[(species[,"Class"] == "amphibians"),]

# Remove the unwanted fields
species.class <- subset(species.class,
select = -c(Taxon_Id, Kingdom, Class, EPBC_status))

# Then to finish things off cleanly, export the data
write.csv(species.class, file = "Queensland_amphibians.csv", row.names = FALSE)