Question

我正在努力从R中的字符串中提取多个变量。

该列如下所示：

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

我需要新的专栏：

7位数字标识符（＆＃34; 1234567＆＃34;）
NAME
每个4位数值
每个位置
3位数值

str_sub()无法正常工作，因为字符串某些部分的长度是可变的。

我尝试gsub，但由于某些特殊字符会重复多次（即＆＃34;：＆＃39;和＆＃34; - ＆＃34;）我无法使用他们提取一个明确定义的字符串部分。

Answer 1

为了避免冗长的正则表达式，一个选项是使用str_split_fixed将[_:-]作为分隔符将列拆分为矩阵，删除不需要的列并从最后一个中提取数值柱：

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

如果你保持＆＃34;冗长的＆＃34;正则表达式，然后你可以做这样的事情（并在以后添加记录验证，因为你已经嵌入字段长度）：

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

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）

2 个答案: