Exercise

• Here is a slightly modified demo:

  demo <- c("https://www.google.com", "http://www.r-project.org",
            "https://www.linkedin.com", "http://xkcd.com")
  
  pattern <- "https://(www\\.)?[^\\.]+\\.(com|org)"
  sub(pattern, "caught ya!", demo)
  

  Please modify pattern so all values will be replaced with "caught ya!"

• Please try to get the email addresses from the following examples:

  demo <- c("this is my email: test1@yahoo.com",
            "test2@yahoo.com",
            "@Doug, please reply to test-user3@yahoo.com")