к счастью, это (как и многие другие полезные вещи) уже реализовано в R.
cbind(state.abb,state.name)
даст вам желаемый результат
state.abb state.name
[1,] "AL" "Alabama"
[2,] "AK" "Alaska"
[3,] "AZ" "Arizona"
[4,] "AR" "Arkansas"
[5,] "CA" "California"
[6,] "CO" "Colorado"
EDIT ::
для получения территорий вы можете использовать пакет USAboundaries:
install.packages('USAboundaries')
library(USAboundaries)
#lookuptable territorys :
state_codes[state_codes$jurisdiction_type == "territory",]
#state_name state_abbr state_code jurisdiction_type
# <chr> <chr> <chr> <chr>
#1 American Samoa "AS" 60 territory
#2 Federated States of Micronesia "FM" 64 territory
#3 Guam "GU" 66 territory
#4 Johnson Atoll "" 67 territory
#5 Marshall Islands "MH" 68 territory
#6 Northern Mariana Islands "MP" 69 territory
#7 Palau "PW" 70 territory
#8 Midway Islands "" 71 territory
#9 Puerto Rico "PR" 72 territory