正则表达式 – 将一列拆分为多个列,R中没有明确的分隔符

我的数据集中有一个名为“Market.Pair”的列,其中包含有关某些航班的出发地和目的地点的信息.例如：

input <- data.frame(Market.Pair = c("US to/from CA","HOU to/from DFW/DAL","EWR/JFK to/from LAX/SFO","US-NYC to/from FR-PAR","US to/from Asia"))
input

所有两个字母代表国家(例如美国,加州).
所有三个字母单词(或由“/”分隔的多个三个字母单词)代表机场(例如HOU,DFW / DAL).
所有XX-XXX形式的单词代表城市(例如US-NYC).
其他词汇代表地区,例如亚洲或欧洲.

我想将此列拆分为多个列：

output<- data.frame(Air.1 = c("HOU","EWR/JFK","",""),Air.2 = c("DFW/DAL","LAX/SFO",City.1 = c("","US-NYC",City.2 = c("","FR-PAR",Country.1 = c("","US","US"),Coutry.2 = c("","CA",Region.1 = c("","Asia"),Region.2 = c("",""))
output

我是正则表达式的新手,所以任何帮助都将不胜感激！

解决方法

input <- data.frame(Market.Pair = c("US to/from CA","US to EMEA/India"))

sp <- strsplit(as.character(input$Market.Pair),'\\s+to(/from)?\\s+')

f <- Vectorize(function(x)
  if (grepl('\\-',x)) 'City' else if (nchar(x) == 2) 'Country' else
    if (grepl('^[A-Z]+/[A-Z]+$|^[A-Z]+$',x)) 'Air' else 'Region')

dd <- lapply(sp,function(x) {
  ## set up output matrix
  cn <- sort(levels(interaction(c('Air','City','Country','Region'),1:2)))
  m <- matrix('',1,length(cn),dimnames = list(NULL,cn))
  ## use f above and add the suffix
  xx <- f(x)
  nn <- setNames(x,paste(xx,ave(xx,xx,FUN = seq_along),sep = '.'))
  ## match
  m[,names(nn)] <- nn
  m
})
do.call('rbind.data.frame',dd)

#     Air.1   Air.2 City.1 City.2 Country.1 Country.2   Region.1 Region.2
# 1                                      US        CA                    
# 2     HOU DFW/DAL                                                      
# 3 EWR/JFK LAX/SFO                                                      
# 4                 US-NYC FR-PAR                                        
# 5                                      US           EMEA/India