如何确定url对象是否返回"404 Not Found"?

本文介绍了如何确定url对象是否返回"404 Not Found"?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

简单地说:如果

x <- read.csv(url)

存在，则R将返回该URL的内容.如果想尝试，一个很好的例子可能是" ichart.finance.yahoo/table.csv?s=IBM&a = 00& b = 1& c = 2008& d = 03& e = 4&f = 2014& g = d& ignore = .csv ".如果将该特定的URL分配给url并按上述方式运行，它将从Yahoo网站上将包含过去5年IBM股票数据的data.frame加载到x中.

exists, then R will return the contents of that url. A good example, if you want to try it, might be "ichart.finance.yahoo/table.csv?s=IBM&a=00&b=1&c=2008&d=03&e=4&f=2014&g=d&ignore=.csv" . That particular url, if assigned to url and run as above, will load up a data.frame into x from the Yahoo website containing the past 5 years of IBM stock data.

但是，如何事先告诉您是否有给定的网址会让您得到404错误?

But how to tell, beforehand, if any given url will get you 404'd ?

类似:

is.404.or.not(url)

或者也许

status(connect.to(url))

谢谢！

推荐答案

您可以使用RCurl软件包:

R> library(RCurl) Loading required package: bitops R> url.exists("google") [1] TRUE R> url.exists("csgillespie") [1] FALSE

或者，您可以使用httr软件包

Alternatively, you could use the httr package

R> library(httr) R> http_status(GET("google")) $category [1] "success" $message [1] "success: (200) OK" R> http_status(GET("csgillespie")) $category [1] "server error" $message [1] "server error: (503) Service Unavailable"