使用R从文本中提取子字符串

Question

我有一个字符串数据如下：

a<-  "\n    Update Your Profile to Dissolve This Message\nSocial Media Learning and behaviour\n        Uploaded on May 3, 2020 at 10:56 in Research\n            View Forum\n        \n"

为此我必须提取字符串 "Social Media Learning and behaviour" 我使用了以下代码：

gsub("        Uploaded on .* ", "", gsub("\n    Update Your Profile to Dissolve This Message\n", "",a))

这给我的输出如下

"Social Media Learning and behaviour\n\n"

我无法匹配准确的模式。在没有“\n\n”

的情况下提取 "Social Media Learning and behaviour" 的确切模式是什么

Answer 1

您可以提取 "Update Your Profile to Dissolve This Message" 和 "Uploaded on"

之间的部分

sub(".*Update Your Profile to Dissolve This Message\n(.*)\n\s+Uploaded on.*", "\1", a)
#[1] "Social Media Learning and behaviour"

您还可以使用 stringr

中的 str_match

stringr::str_match(a, "Update Your Profile to Dissolve This Message\n(.*)\n\s+Uploaded on")[, 2]

Answer 2

您可以捕获组中的上一行并匹配包含已上传的下一行：

(.*)\r?\n[^\S\r\n]+Uploaded on

Regex demo

a<-  "\n    Update Your Profile to Dissolve This Message\nSocial Media Learning and behaviour\n        Uploaded on May 3, 2020 at 10:56 in Research\n            View Forum\n        \n"
stringr::str_match(a, "(.*)\r?\n[^\S\r\n]+Uploaded on")

使用R从文本中提取子字符串

Extraction of sub string from the text using R

regex

r

gsub