读取分隔文件，其中分号显示为分隔符和字符串

Posted 2021-04-14

我正在尝试读取一个文件，其中一些行在文本字符串中包含额外的分号（我不知道是什么导致了这个）

例如，这是一个具有相同问题的超简化数据：

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，我试着用它读取：

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

但是没有雪茄......这有点不可能阅读，如果没有干净的解决方案，我想跳过这些行。

答案

如果您只想删除没有预期分隔符数的行：

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, '
'))

# 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"  

另一答案

您可以尝试删除文本字符串中的所有分号（这假设所有不需要的分号都完全在字符串中：

gsub("(\S);(\S)", "\1\2", bad_data, perl=TRUE)
[1] "100; Mc Donalds; Seattle; normal day
             115; Starbucks; Boston; normal day
             400; PF Chang; Chicago; busy day
             400; Texas; busy day
             10; Dunkin Donuts; Washington; lazy day"