[R] Change state names to abbreviations in an irregular list of names, abbreviations, null values, and foreign provinces

[Ben Bolker]

David Kikuchi <dkikuchi <at> email.unc.edu> writes:

> I'm trying to create maps of reptile abundance in different states & 
> counties using data from Herp.net, which provides lists of specimens 
> with the places that they were found.  First I would like to parse the 
> list by state using 2-letter abbreviations, since I'm focusing on 
> certain regions.  To do this, I've been trying to create a vector 
> (state2) that gives all state names as 2-letter abbreviations, using 
> advice given on the thread: 
> http://tolstoy.newcastle.edu.au/R/help/05/09/12136.html
> 

  [snip] 

> state2 <- rep(NA,length(tener$State.Province))
> for(i in 1:length(tener$Institution)){
>      if(tener$State.Province[i] != ''){
>          if(grep(tener$State.Province[i],state.name) > 0){
>              state2[i] <- state.abb[grep(tener$State.Province[i], 
> state.name)]
>          }
>          else{
>               state2[i] <- NA
>          }
>      }
>      else{
>          state2[i] <- NA
>      }
> }


  I think you might be looking for length(grep(...))>0 , but
is this an easier way?

state.province <- c("Massachusetts","Ontario","Cuba","","Pennsylvania")
myabbr <- state.abb[match(state.province,state.name)]

myabbr
## [1] "MA" NA   NA   NA   "PA"

   (You described your problem pretty clearly, but a reproducible
example would have been nice)