读取分隔文件，其中分号作为分隔符出现在字符串中

Question

我正在尝试读取一个文件，其中某些行在文本字符串中包含额外的分号(我不知道是什么原因导致的)

作为示例，这是具有相同问题的 super 简化数据:

bad_data <- "100; Mc Donalds; Seattle; normal day
             115; Starbucks; Boston; normal day
             400; PF Chang; Chicago; busy day
             400;; Texas; busy day
             10; D;unkin Donuts; Washin;gton; lazy day"

所以它没有标题，我尝试用以下内容读取它:

library(data.table)
fread(bad_data, sep = ";", header = F, na.strings = c("", NA), strip.white = T)

但是没有雪茄...这有点难以阅读，如果没有干净的解决方案，我想跳过这些行。

Answer 1

如果您只想删除没有预期分隔符数量的行:

library(stringi)
library(magrittr)

bad_data <- 
"100; Mc Donalds; Seattle; normal day
115; Starbucks; Boston; normal day
400; PF Chang; Chicago; busy day
400;; Texas; busy day
10; D;unkin Donuts; Washin;gton; lazy day"

# split to lines. you could also use readLines if it's coming from a file
text_lines <- unlist(strsplit(bad_data, '\n'))

# which lines contain the expected number of semicolons?
good_lines <- sapply(text_lines, function(x) stri_count_fixed(x, ';') == 3)

# for those lines, split to vectors and (optional bonus) trim whitespace
good_vectors <- lapply(
  text_lines[good_lines], 
  function(x) x %>% strsplit(';') %>% unlist %>% trimws)

# flatten to matrix (from which you can make a data.frame or whatever you want)
my_mat <- do.call(rbind, good_vectors)

结果:

> my_mat
     [,1]  [,2]         [,3]      [,4]        
[1,] "100" "Mc Donalds" "Seattle" "normal day"
[2,] "115" "Starbucks"  "Boston"  "normal day"
[3,] "400" "PF Chang"   "Chicago" "busy day"  
[4,] "400" ""           "Texas"   "busy day"