我试图在r 的文本文件中查找所有包含任何格式数字的句子，并将其替换为它们周围的主题标签。
例如输入以下内容：
ex <- c("I have $5.78 in my account","Hello my name is blank","do you want 1,785 puppies?",
"I love stack overflow!","My favorite numbers are 3, 14,568, and 78")
作为函数的输出，我正在寻找：
> "I have #$5.78# in my account"
> "do you want #1,785# puppies?"
> "My favorite numbers are #3#, #14,568#, and #78#"
【问题讨论】：
标签： r r regex text-files gsub hashtag
周围的数字是直截了当的，假设所有带有数字、句点、逗号和美元符号的东西都包括在内。
gsub("\\b([-$0-9.,]+)\\b", "#\\1#", ex)
# [1] "I have $#5.78# in my account"
# [2] "Hello my name is blank"
# [3] "do you want #1,785# puppies?"
# [4] "I love stack overflow!"
# [5] "My favorite numbers are #3#, #14,568#, and #78#"
仅过滤掉编号的条目：
grep("\\d", gsub("\\b([-$0-9.,]+)\\b", "#\\1#", ex), value = TRUE)
# [1] "I have $#5.78# in my account"
# [2] "do you want #1,785# puppies?"
# [3] "My favorite numbers are #3#, #14,568#, and #78#"
【讨论】：
我们可以使用gsub
gsub("(?<=\\s)(?=[$0-9])|(?<=[0-9])(?=,?[ ]|$)", "#", ex, perl = TRUE)
#[1] "I have #$5.78# in my account" "Hello my name is blank"
#[3] "do you want #1,785# puppies?" "I love stack overflow!"
#[5] "My favorite numbers are #3#, #14,568#, and #78#"
【讨论】：
另一种循序渐进的方法是使用grep 识别包含模式"[0-9]" 的文本文件的元素，使用ex[....] 识别具有数字条目的文本元素子集，并使用管道运算符%>% from library(dplyr) 将子集传递给gsub，然后使用@r2evans 的逻辑在数字条目周围放置主题标签，如下所示：
library(dplyr)
ex[do.call(grep,list("[0-9]",ex))] %>% gsub("\\b([-$0-9.,]+)\\b", "#\\1#",.)
代码的
do.call(grep,list("[0-9]",ex))部分返回 ex 中带有数字条目的文本元素的索引。输出
library(dplyr)
ex[do.call(grep,list("[0-9]",ex))] %>% gsub("\\b([-$0-9.,]+)\\b", "#\\1#",.)
[1] "I have $#5.78# in my account" "do you want #1,785# puppies?"
[3] "My favorite numbers are #3#, #14,568#, and #78#"
【讨论】：