Question

我有这段代码：

library(rvest)
url_list <- c("https://github.com/rails/rails/pull/100", 
               "https://github.com/rails/rails/pull/200", 
               "https://github.com/rails/rails/pull/300")

mine <- function(url){
  url_content  <- html(url)
  url_mainnode <- html_node(url_content, "*")
  url_mainnode_text <- html_text(url_mainnode)
  url_mainnode_text <- gsub("\n", "", url_mainnode_text) # clean up the text
  url_mainnode_text
}

messages <- lapply(url_list, mine)

然而，随着我使列表更长，我倾向于遇到

Error in html.response(r, encoding = encoding) : 
  server error: (500) Internal Server Error

我知道在Ruby中我可以使用rescue继续遍历列表，即使某些函数尝试失败也是如此。 R中有类似的东西吗？

Answer 1

一种选择是使用try()。有关详细信息，请参阅here。这是一个实现：

library(rvest)
url_list <- c("https://github.com/rails/rails/pull/100", 
               "https://github.com/rails/rails/pull/200", 
               "https://github.com/rails/rails/pull/300")

mine <- function(url){
  try(url_content  <- html(url))
  url_mainnode <- html_node(url_content, "*")
  url_mainnode_text <- html_text(url_mainnode)
  url_mainnode_text <- gsub("\n", "", url_mainnode_text) # clean up the text
  url_mainnode_text
}

messages <- lapply(url_list, mine)

＆＃34;救援＆＃34; R中的命令？

1 个答案: