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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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
