将字符串拆分为行和列

我有一根又长又大的绳子：

mystr <- "foo   one   undefined + foo   two   undefined + BAR   three   undefined + "

我想把它变成

   x1    x2        x3
1 foo   one undefined
2 foo   two undefined
3 bar three undefined

通过使用+创建新行，然后用空格创建列。这可能吗？我尝试使用 str_split 和 mutate 但我似乎无法弄清楚如何创建新行。任何帮助表示赞赏！

我们可以用read.table更换后+ with \n using gsub in base R

read.table(text = gsub("+", "\n", mystr, fixed = TRUE),
       header = FALSE, col.names = paste0('x', 1:3))
#    x1    x2        x3
#1 foo   one undefined
#2 foo   two undefined
#3 BAR three undefined

或者使用strsplit with read.table

read.table(text = strsplit(mystr, " + ", fixed = TRUE)[[1]], header = FALSE)

或者我们可以使用fread

library(data.table)
fread(text = gsub("+", "\n", mystr, fixed = TRUE), header = FALSE)

或者使用tidyverse

library(dplyr)
library(tidyr)
tibble(col1 = mystr) %>% 
   separate_rows(col1, sep="\\s*\\+\\s*") %>%
   separate(col1, into = c('x1', 'x2', 'x3')) %>%
   na.omit
# A tibble: 3 x 3
#  x1    x2    x3       
#  <chr> <chr> <chr>    
#1 foo   one   undefined
#2 foo   two   undefined
#3 BAR   three undefined