使用R从文本中提取子字符串[重复]答案

【问题标题】：Extraction of sub string from the text using R [duplicate]使用R从文本中提取子字符串[重复]
【发布时间】：2020-09-18 15:48:09
【问题描述】：

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"

我必须为此提取字符串“社交媒体学习和行为”，我使用了以下代码：

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

这给了我如下输出

"Social Media Learning and behaviour\n\n"

我无法匹配确切的模式。在没有“\n\n”的情况下提取“社交媒体学习和行为”的确切模式是什么

【问题讨论】：

您也可以匹配捕获组中的前一行，并匹配其后包含 Uploaded ^(.*)\r?\n Uploaded on regex101.com/r/bF5GKT/1 的行

标签： r regex gsub

【解决方案1】：

您可以捕获组中的上一行并匹配包含 Uploaded 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")

【讨论】：

【解决方案2】：

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"

您也可以从stringr 使用str_match

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

【讨论】：