使用R从文本中提取子字符串

Question

我有如下字符串数据：

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，我使用下面的代码来提取字符串“ Social Media Learning and behaviour”：

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

这给我输出如下

"Social Media Learning and behaviour\n\n"

我无法匹配确切的模式。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？

我有如下字符串数据：a

Answer 1

您可以提取"Update Your Profile to Dissolve This Message"和"Uploaded on"之间的部分

Answer 2

您可以捕获组中的前一行，并匹配包含Uploaded的下一行：