我正在尝试解析以下 url 上的 xml 文档：
"http://ifis.iowafloodcenter.org/ifis/ws/sites.php?format=xml"
使用以下代码：
library(XML)
ifc=xmlParse("http://ifis.iowafloodcenter.org/ifis/ws/sites.php?format=xml")
但我收到以下错误：
No such file or directoryfailed to load external entity
"http://ifis.iowafloodcenter.org/ifis/ws/sites.php?format=xml"
Error: 1: No such file or directory2: failed to load external entity "http://ifis.iowafloodcenter.org/ifis/ws/sites.php?format=xml"