Scraping with rvest - complete with NAs when tag is not present

Question

I want to parse this HTML: and get this elements from it:

a) p tag, with class: \"normal_encontrado\".
b) div with c

Answer 1

Using the XML package parse the input with xmlTreeParse and then use xpathSApply to interate over the product_price class div nodes. For each such node the anonyous function gets the value of the div and p subnodes. The resulting character matrix m is reworked into a data frame DF and the columns are cleaned removing any character that is not a dot or digit and also removing any dot followed by a non-digit. Copnvert result to numeric. Note that no special processing for the missing p case is needed.

# input

Lines <- '




  

    S/. 2,799.00
  

  

    S/. 2,299.00
  
    



  

    S/. 4,999.00
  


'

# code to read input and produce a data.frame

library(XML)
doc <- xmlTreeParse(Lines, asText = TRUE, useInternalNodes = TRUE)

m <- xpathSApply(doc, "//div[@class = 'product_price']", function(node) {
  list(p = xmlValue(node[["p"]]), div = xmlValue(node[["div"]])) })

DF <- as.data.frame(t(m), stringsAsFactors = FALSE) # rework into data frame
DF[] <- lapply(DF, function(x) as.numeric(gsub("[^.0-9]|[.]\\D", "", x))) # clean

The result is:

> DF
     p  div
1 2799 2299
2   NA 4999