正则表达式提取“--!!”之后的所有文本在 R dplyr 中

我试图在 R 中使用 dplyr 来提取由变量的某些实例过滤的数据框中变量字符串后面的子字符串name在下面的例子中。我正在尝试将所需的结果传递到一个名为的新变量中income_rent.

我是正则表达式的新手。我的尝试是：

income_cashrent <- v18 %>% 
filter(str_detect(name, "B25122")) %>% 
mutate(income_rent = str_extract(label, "[^--!!]*$"))

但是，我得到的结果是：Error in stri_extract_first_regex(string, pattern, opts_regex = opts(pattern)) : Syntax error in regexp pattern. (U_REGEX_RULE_SYNTAX)

前四行name are:

Estimate!!Total
Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000
Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000!!With cash rent
Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000!!With cash rent!!Less than $100

期望的结果是：

[not sure how to indicate an empty result here]
Less than $10,000
Less than $10,000!!With cash rent
Less than $10,000!!With cash rent!!Less than $100

到目前为止，我无法对此进行调试，请查阅堆栈上的其他正则表达式示例。任何指导都将受到欢迎。预先感谢大家！

regmatches(vec, gregexpr("(?<=--!!).*", vec, perl = TRUE))
# [[1]]
# character(0)
# [[2]]
# [1] "Less than $10,000"
# [[3]]
# [1] "Less than $10,000!!With cash rent"
# [[4]]
# [1] "Less than $10,000!!With cash rent!!Less than $100"

If you unlist从这里开始，您会注意到您“丢失”了第一个条目，不确定这是否是一个问题。

unlist(regmatches(vec, gregexpr("(?<=--!!).*", vec, perl = TRUE)))
# [1] "Less than $10,000"                                
# [2] "Less than $10,000!!With cash rent"                
# [3] "Less than $10,000!!With cash rent!!Less than $100"

如果这是一个问题，那么

vecout <- regmatches(vec, gregexpr("(?<=--!!).*", vec, perl = TRUE))
unlist(replace(vecout, lengths(vecout) < 1, NA))
# [1] NA                                                 
# [2] "Less than $10,000"                                
# [3] "Less than $10,000!!With cash rent"                
# [4] "Less than $10,000!!With cash rent!!Less than $100"

（或者你可以替换为""以及。）

In a dplyr管道：

tibble(vec = c("Estimate!!Total",
# "Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000",
# "Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000!!With cash rent",
# "Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000!!With cash rent!!Less than $100")) %>%
  mutate(out = regmatches(vec, gregexpr("(?<=--!!).*", vec, perl = TRUE)), out = replace(out, lengths(vecout) < 1, NA), out = unlist(out))
+ + # A tibble: 4 x 2
#   vec                                             out                           
#   <chr>                                           <chr>                         
# 1 Estimate!!Total                                 <NA>                          
# 2 Estimate!!Total!!Household income in the past ~ Less than $10,000             
# 3 Estimate!!Total!!Household income in the past ~ Less than $10,000!!With cash ~
# 4 Estimate!!Total!!Household income in the past ~ Less than $10,000!!With cash ~

Data:

vec <- c("Estimate!!Total",
"Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000",
"Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000!!With cash rent",
"Estimate!!Total!!Household income in the past 12 months (in 2018 inflation-adjusted dollars) --!!Less than $10,000!!With cash rent!!Less than $100")