Scraping Wikipedia HTML table with images, text, and blank cells with R

Question

The table I am interested in is the Wikipedia table of Michelin-starred restaurants in NYC, and the number of stars awarded is indicated by pictures.

I was able to scrape the table using two steps (first get the words in the "Name" and "Borough" columns, second get the alt tags in the table body), but I want to know if it can be done in one step. I was able to scrape the data using the rvest package.

Since wikipedia pages can't be read by the XML::readHTMLTable function, I tried the htmltab package with no luck, because I couldn't figure out the function needed for the bodyFun argument. Truth be told, I am a newbie to web scraping...and functions.

Questions I referred to for reference:

Scraping html table with images using XML R package

Scraping html tables into R data frames using the XML package

Here is my code:

library(stringr)
library(rvest)
library(data.table)

url <- "http://en.wikipedia.org/wiki/List_of_Michelin_starred_restaurants_in_New_York_City"

#Scrape the first two columns, restaurant name and borough
name.boro <- url %>% read_html() %>% html_nodes("table") %>% html_table(fill = TRUE)
name.boro <- as.data.table(name.boro[[1]])
name.boro[, 3:length(name.boro) := NULL]
135 * 13 #1,755 cells in first table

#scrape tables for img alt 
#note that because I used the "td" node, entries for all cells in all tables were pulled
stars <- url %>% read_html() %>% html_nodes("td") %>% html_node("img") %>% html_attr("alt")
stars 

#Make vector of numbers to index each column
df <- vector("list", 13)
for (i in 1:13){
  df[[i]] <- seq(i, 1755, 13)
}

#Put everything together
Mich.Guide <- name.boro 
Mich.Guide[, c("X2006", "X2007", "X2008", "X2009", "X2010", "X2011", "X2012", "X2013", "X2014", "X2015", 
               "X2016") := .(stars[unlist(df[3])], stars[unlist(df[4])], stars[unlist(df[5])], 
                             stars[unlist(df[6])], stars[unlist(df[7])], stars[unlist(df[8])], 
                             stars[unlist(df[9])], stars[unlist(df[10])], stars[unlist(df[11])], 
                             stars[unlist(df[12])], stars[unlist(df[13])] )]

Thank you!

Rentrop · Accepted Answer

You can try the following

require(rvest)
url <- "http://en.wikipedia.org/wiki/List_of_Michelin_starred_restaurants_in_New_York_City"
doc <- read_html(url)
col_names <- doc %>% html_nodes("#mw-content-text > table > tr:nth-child(1) > th") %>% html_text()
tbody <- doc %>% html_nodes("#mw-content-text > table > tr:not(:first-child)")

extract_tr <- function(tr){
  scope <- tr %>% html_children()
  c(scope[1:2] %>% html_text(),
    scope[3:length(scope)] %>% html_node("img") %>% html_attr("alt"))
}

res <- tbody %>% sapply(extract_tr)
res <- as.data.frame(t(res), stringsAsFactors = FALSE)
colnames(res) <- col_names

Now you have the raw-table. I leave the parsing of the columns to integer and the column-names to you

Scraping Wikipedia HTML table with images, text, and blank cells with R

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