如何从R中的复杂字符串中提取多个新列(str_sub似乎没有做到这一点)

Question

我正在努力从r中的字符串提取多个变量

该列看起来像这样:

7 digit identifier _ NAME: 4 digit value - 4 digit value 4 digit value location1 - location2: 7-digit identifier _ junk _ junk _ 3 digit value with junk attached

所以例如:

1234567_NAME:0011-1234-0176-town-car:1234567_000001_original_010qyz

我需要新的列:

• 7位标识符("1234567")

名称
• 每一个4位数值
每个位置
• 3位值

str_sub()不工作，因为字符串的某些部分的长度是可变的。

我尝试了gsub，但由于一些特殊字符重复多次(即":"one_answers"-")，我不能使用它们来提取字符串的一个定义良好的部分。

Answer 1

为了避免冗长的正则表达式，一种选择是使用str_split_fixed将列分割成一个矩阵，使用[_:-]作为分隔符，删除不需要的列并从最后一列提取数值:

s <- "1234567_NAME:0011-1234-0176-town-car:1234567_000001_original_010qyz"
ss <- c(s,s,s)
library(stringr)
mat <- str_split_fixed(ss, "[_:-]", 11)[,-c(9, 10)]
mat
#     [,1]      [,2]   [,3]   [,4]   [,5]   [,6]   [,7]  [,8]      [,9]    
#[1,] "1234567" "NAME" "0011" "1234" "0176" "town" "car" "1234567" "010qyz"
#[2,] "1234567" "NAME" "0011" "1234" "0176" "town" "car" "1234567" "010qyz"
#[3,] "1234567" "NAME" "0011" "1234" "0176" "town" "car" "1234567" "010qyz"
mat[,9] <- sub("(\d{3}).*", "\1", mat[,9])
mat
#     [,1]      [,2]   [,3]   [,4]   [,5]   [,6]   [,7]  [,8]      [,9] 
#[1,] "1234567" "NAME" "0011" "1234" "0176" "town" "car" "1234567" "010"
#[2,] "1234567" "NAME" "0011" "1234" "0176" "town" "car" "1234567" "010"
#[3,] "1234567" "NAME" "0011" "1234" "0176" "town" "car" "1234567" "010"

Answer 2

如果您保留"冗长"正则表达式，那么您可以这样做(并在稍后添加记录验证，因为您已经嵌入了字段长度):

library(stringi)
library(purrr)
pat <- "(.{7})_([[:alnum:][:space:]]+):([[:digit:]]{4})-([[:digit:]]{4})-([[:digit:]]{4})-([[:alnum:][:space:]]+)-([[:alnum:][:space:]]+):([[:digit:]]{7})_[[:alnum:][:space:]]+_[[:alnum:][:space:]]+_([[:digit:]]{3})"
dat <- "1234567_NAME:0011-1234-0176-town-car:1234567_000001_original_010qyz"
dat <- rep(dat, 10)
cols <- c("id", "name", "val1", "val2", "val3", "loc1", "loc2", "val3")
stri_match_all_regex(dat, pat) %>% 
  map_df(~setNames(as.list(.[,c(2:8,10)]), cols))
## # A tibble: 10 x 7
##         id  name  val1  val2  val3  loc1  loc2
##      <chr> <chr> <chr> <chr> <chr> <chr> <chr>
## 1  1234567  NAME  0011  1234   010  town   car
## 2  1234567  NAME  0011  1234   010  town   car
## 3  1234567  NAME  0011  1234   010  town   car
## 4  1234567  NAME  0011  1234   010  town   car
## 5  1234567  NAME  0011  1234   010  town   car
## 6  1234567  NAME  0011  1234   010  town   car
## 7  1234567  NAME  0011  1234   010  town   car
## 8  1234567  NAME  0011  1234   010  town   car
## 9  1234567  NAME  0011  1234   010  town   car
## 10 1234567  NAME  0011  1234   010  town   car