从R中的文本字符串中提取N个匹配项？

我在R中使用stringr，我有一个文本字符串，列出了新闻文章的标题。我想提取这些标题，但只提取出现的前N个标题。在我的文本字符串示例中，我有三个文章标题，但我只想提取前两个

我如何告诉Stru_extract只收集前两个标题？多谢各位

下面是我当前的代码和示例文本

library(stringr)

下面是示例文本

texting <- ("Time: Friday, September 14, 2018 4:34:00 PM EDT\r\nJob Number: 73591483\r\nDocuments (100)\r\n 1. U.S. Stocks Rebound Slightly After Tech-Driven Slump\r\n   Client/Matter: -None-\r\n   Search Terms: trade war or US-China trade or china tariff and not dealbook\r\n   Search Type: Terms and Connectors\r\n   Narrowed by:\r\n             Content Type                         Narrowed by\r\n             News                                 Sources: The New York Times; Content Type: News;\r\n                                                  Timeline: Jan 01, 2018 to Dec 31, 2018\r\n 2. Shifting Strategy on Tariffs\r\n   Client/Matter: -None-\r\n   Search Terms: trade war or US-China trade or china tariff and not dealbook\r\n 100. Example")

---

我只想让它收集前两个匹配项。

您可以使用选项

simplify=TRUE

获取向量作为结果，而不是列表。然后，从向量中选取前N个元素

titles.1 <- str_extract_all(texting, "\\d+\\.\\s.+", simplify = TRUE)[1:2]

标题。1
[[1]]

[1] "1. U.S. Stocks Rebound Slightly After Tech-Driven Slump"

[2] "2. Shifting Strategy on Tariffs"                        

[3] "100. Example"

titles.1 <- str_extract_all(texting, "\\d+\\.\\s.+", simplify = TRUE)[1:2]