如何在R中获得美国州名的缩写？
美国有五十个州，其中几个州的简称很短，但大多数州的名称都很长。因此，如果我们要处理的州名称为美国的数据，则使用州名称访问州会有点复杂，因此最好使用缩写。我们可以借助state.abb函数获得状态名称的缩写。
例子
state.abb[which(state.name=="New York")] [1] "NY" state.abb[which(state.name=="California")] [1] "CA" state.abb[which(state.name=="Texas")] [1] "TX" state.abb[which(state.name=="Florida")] [1] "FL" state.abb[which(state.name=="Washington")] [1] "WA" state.abb[which(state.name=="Michigan")] [1] "MI" state.abb[which(state.name=="New Jersey")] [1] "NJ" state.abb[which(state.name=="Arizona")] [1] "AZ" state.abb[which(state.name=="Pennsylvania")] [1] "PA" state.abb[which(state.name=="Alaska")] [1] "AK" state.abb[which(state.name=="Massachusetts")] [1] "MA" state.abb[which(state.name=="Ohio")] [1] "OH" state.abb[which(state.name=="Georgia")] [1] "GA" state.abb[which(state.name=="Minnesota")] [1] "MN" state.abb[which(state.name=="Hawaii")] [1] "HI" state.abb[which(state.name=="Illinois")] [1] "IL" state.abb[which(state.name=="Colorado")] [1] "CO" state.abb[which(state.name=="North Carolina")] [1] "NC" state.abb[which(state.name=="Virginia")] [1] "VA" state.abb[which(state.name=="Alabama")] [1] "AL" state.abb[which(state.name=="Oregon")] [1] "OR" state.abb[which(state.name=="Indiana")] [1] "IN" state.abb[which(state.name=="Maryland")] [1] "MD" state.abb[which(state.name=="Missouri")] [1] "MO" state.abb[which(state.name=="Tennessee")] [1] "TN" state.abb[which(state.name=="Wisconsin")] [1] "WI" state.abb[which(state.name=="Montana")] [1] "MT" state.abb[which(state.name=="South Carolina")] [1] "SC" state.abb[which(state.name=="Maine")] [1] "ME" state.abb[which(state.name=="Utah")] [1] "UT" state.abb[which(state.name=="Connecticut")] [1] "CT" state.abb[which(state.name=="Mississippi")] [1] "MS" state.abb[which(state.name=="Wyoming")] [1] "WY" state.abb[which(state.name=="Iowa")] [1] "IA" state.abb[which(state.name=="Louisiana")] [1] "LA" state.abb[which(state.name=="Kentucky")] [1] "KY" state.abb[which(state.name=="Nevada")] [1] "NV" state.abb[which(state.name=="Rhode Island")] [1] "RI" state.abb[which(state.name=="Arkansas")] [1] "AR" state.abb[which(state.name=="New Mexico")] [1] "NM" state.abb[which(state.name=="Idaho")] [1] "ID" state.abb[which(state.name=="Delaware")] [1] "DE" state.abb[which(state.name=="Nebraska")] [1] "NE" state.abb[which(state.name=="Kansas")] [1] "KS" state.abb[which(state.name=="Vermont")] [1] "VT" state.abb[which(state.name=="New Hampshire")] [1] "NH" state.abb[which(state.name=="South Dakota")] [1] "SD" state.abb[which(state.name=="Oklahoma")] [1] "OK" state.abb[which(state.name=="West Virginia")] [1] "WV" state.abb[which(state.name=="North Dakota")] [1] "ND"