我想在 R 中編碼，它可以下載此 URL 上給出的所有 pdf：https ://www.rbi.org.in/scripts/AnnualPublications.aspx?head=Handbook of Statistics on Indian Economy 然后下載檔案夾中的所有pdf。我在https://towardsdatascience.com的幫助下嘗試了以下代碼，但代碼出錯了
library(tidyverse)
library(rvest)
library(stringr)
library(purrr)
page <- read_html("https://www.rbi.org.in/scripts/AnnualPublications.aspx?
head=Handbook of Statistics on Indian Economy") %>%
raw_list <- page %>% # takes the page above for which we've read the html
html_nodes("a") %>% # find all links in the page
html_attr("href") %>% # get the url for these links
str_subset("\\.pdf") %>% # find those that end in pdf only
str_c("https://rbi.org.in", .) %>% # prepend the website to the url
map(read_html) %>% # take previously generated list of urls and read them
map(html_node, "#raw-url") %>% # parse out the 'raw' url - the link for the download button
map(html_attr, "href") %>% # return the set of raw urls for the download buttons
str_c("https://www.rbi.org.in", .) %>% # prepend the website again to get a full url
for (url in raw_list)
{ download.file(url, destfile = basename(url), mode = "wb")
}
我無法解釋為什么代碼出錯。如果有人可以幫助我。
uj5u.com熱心網友回復：
有一些小錯誤。該網站使用大寫字母作為 PDF 結尾，您不需要使用str_c("https://rbi.org.in", .). 最后，我認為使用 purrr 的 walk2 函式更流暢（因為它可能在原始代碼中）。
我沒有執行代碼，因為我不需要那么多pdf，所以，報告它是否有效。
library(tidyverse)
library(rvest)
library(stringr)
library(purrr)
page <- read_html("https://www.rbi.org.in/scripts/AnnualPublications.aspx?head=Handbook of Statistics on Indian Economy")
raw_list <- page %>% # takes the page above for which we've read the html
html_nodes("a") %>% # find all links in the page
html_attr("href") %>% # get the url for these links
str_subset("\\.PDF") %>%
walk2(., basename(.), download.file, mode = "wb")
uj5u.com熱心網友回復：
在嘗試運行您的代碼時，我遇到了“驗證您是人類”和“請確保您的瀏覽器啟用了 Javascript”對話框。這表明您無法使用 Rvest 打開頁面，而需要使用RSelenium 瀏覽器自動化。
這是使用 RSelenium 的修改版本
library(tidyverse)
library(stringr)
library(purrr)
library(rvest)
library(RSelenium)
rD <- rsDriver(browser="firefox", port=4545L, verbose=F)
remDr <- rD[["client"]]
remDr$navigate("https://www.rbi.org.in/scripts/AnnualPublications.aspx?head=Handbook of Statistics on Indian Economy")
page <- remDr$getPageSource()[[1]]
read_html(page) -> html
html %>%
html_nodes("a") %>%
html_attr("href") %>%
str_subset("\\.PDF") -> urls
urls %>% str_split(.,'/') %>% unlist() %>% str_subset("\\.PDF") -> filenames
for(u in 1:length(urls)) {
cat(paste('downloading: ', u, ' of ', length(urls) '\n'))
download.file(urls[u], filenames[u], mode='wb')
Sys.sleep(1)
}
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