在R中使用gsub清理推文

我正在尝试使用gsub清理一堆推文

V3
1  Well: Getting Insurance to Pay for Midwives http://xxxxxxxxx
2  Lightning may be giving you a headache http://xxxxxxxx
3  New York City is requiring flu shots for kids under 5 in city preschools and day care. Do your kids get the flu shot? http://xxxxxxxx
4  VIDEO: Can we erase memories entirely? http://xxxxxxxx
5  Artificial sweeteners are a $1.5-billion-a-year market @kchangnyt reported last year. http://xxxxxxxx

我尝试使用以下代码删除所有链接（摘自上一个问题）：

---

有人能解释一下为什么第一种情况下的代码不能产生期望的结果吗？

这是因为

\w

只识别字母数字字符。由于http后面总是跟“：/”，

\w

不承认它是合法表达式

相比之下，

*

只拾取“http”后面的任何内容，这样就可以了

newdf1$V3 <- gsub("http\\w+", "", newdf1$V3)

V3
1  Well: Getting Insurance to Pay for Midwives 
2  Lightning may be giving you a headache 
3  New York City is requiring flu shots for kids under 5 in city preschools and day care. Do your kids get the flu shot? 
4  VIDEO: Can we erase memories entirely? 
5  Artificial sweeteners are a $1.5-billion-a-year market @kchangnyt reported last year.