On 7/12/20 10:42 AM, Tiffany Adekola wrote:> Dear All,
>
> I am just learning how to use R programming. I want to extract reviews
> from a page and loop till I extract for all pages:
>
> #specify the first page URL
> fpURL <-
'https://wordpress.org/support/plugin/easyrecipe/reviews/'
>
> #read the HTML contents in the first page URL
> contentfpURL <- read_html(fpURL)
>
> #identify the anchor tags in the first page URL
> fpAnchors <- html_nodes(contentfpURL,
css='a.bbp-topic-permalink')
>
> #extract the HREF attribute value of each anchor tag
> fpHREF <- html_attr(fpAnchors, 'href')
>
> #create empty lists to store titles & contents found in the HREF
> attribute value of each anchor tag
> titles = c()
> contents = c()
>
> #loop the following actions for each HREF found firstpage
> for (u in fpHREF) {
>
> #read the HTML content of the review page
> fpURL = read_html(u)
>
> #identify the title anchor and read the title text
> fpreviewT = html_text(html_nodes(fpURL, css='h1.page-title'))
>
> #identify the content anchor and read the content text
> fpreviewC = html_text(html_nodes(fpURL,
css='div.bbp-topic-content'))
>
> #store the review titles and contents in the previous lists
> titles = c(titles, fpreviewT)
> contents = c(contents, fpreviewC)
> }
> #identify the anchor tag pointing to the next summary page
> npAnchor <- html_text(html_node(contentfpURL, css='a.next
page-numbers'))
>
> #extract the HREF attribute value of the anchor tag pointing to the
> next summary page
> npHREF <- html_attr(npAnchor, 'href')
The error occurs with the line above, but if you look at the argument to
`html_attr` you see that the problem is higher up
str(npAnchor)
# chr NA
Perhaps the problem occurs here:
html_node(contentfpURL, css='a.next page-numbers')
#{xml_missing}
#<NA>
--
David.
>
> #loop the following actions for every next summary page HREF attribute
> for (u in npHREF) {
>
> #specify the URL of the summary page
> spURL <- read_html('npHREF')
>
> #identify all the anchor tags on that summary page
> spAnchors <- html_nodes(spURL, css='a.bbp-topic-permalink')
>
> #extract the HREF attribute value of each anchor tag
> spHREF <- html_attr(spAnchors, 'href')
>
> #loop the following actions for each HREF found on that summarypage
>
> for (u in fpHREF) {
> #read the HTML contents of the review page
> spURL = read_html(u)
>
> #identify the title anchor and read the title text
> spreviewT = html_text(html_nodes(spURL,
css='h1.page-title'))
>
> #identify the content anchor and read the content text
> spreviewC = html_text(html_nodes(spURL,
css='div.bbp-topic-content'))
>
> #store the review titles and contents in the previous lists
> titles = c(titles, spreviewT)
> contents = c(contents, spreviewC)
> }
> }
>
> I got stuck at the step to extract the HREF attribute value of the
> anchor tag pointing to the next summary page with the error: Error in
> UseMethod("xml_attr") :
> no applicable method for 'xml_attr' applied to an object of
class "character"
>
> I will appreciate any help with this task.
> Thanks in advance.
>
> ---Tiffany
>
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