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Follow Up Making a Word Cloud for a Search Result from GScholar Scraper 3 1

Follow Up Making a Word Cloud for a Search Result from GScholar Scraper 3 1

Heres a short follow-up on how to produce a word cloud for a search result from GScholarScraper_3.1:

# File-Name: GScholarScraper_3.1.R
# Date: 2012-08-22
# Author: Kay Cichini
# Email: kay.cichini@gmail.com
# Purpose: Scrape Google Scholar search result
# Packages used: XML
# Licence: CC BY-SA-NC
#
# Arguments:
# (1) input:
# A search string as used in Google Scholar search dialog
#
# (2) write:
# Logical, should a table be writen to user default directory?
# if TRUE ("T") a CSV-file with hyperlinks to the publications will be created.
#
# Difference to version 3:
# (3) added "since" argument - define year since when publications should be returned..
# defaults to 1900..
#
# (4) added "citation" argument - logical, if "0" citations are included
# defaults to "1" and no citations will be included..
# added field "YEAR" to output 
#
# Caveat: if a submitted search string gives more than 1000 hits there seem
# to be some problems (I guess Im being stopped by Google for roboting the site..)
#
# And, there is an issue with this error message:
# > Error in htmlParse(URL): 
# > error in creating parser for http://scholar.google.com/scholar?q
# I havent figured out his one yet.. most likely also a Google blocking mechanism..
# Reconnecting / new IP-address helps..


GScholar_Scraper <- function(input, since = 1900, write = F, citation = 1) {

 require(XML)

 # putting together the search-URL:
 URL <- paste("http://scholar.google.com/scholar?q=", input, "&as_sdt=1,5&as_vis=", 
 citation, "&as_ylo=", since, sep = "")
 cat(" The URL used is: ", " ---- ", paste("* ", "http://scholar.google.com/scholar?q=", input, "&as_sdt=1,5&as_vis=", 
 citation, "&as_ylo=", since, " *", sep = ""))
 
 # get content and parse it:
 doc <- htmlParse(URL)
 
 # number of hits:
 h1 <- xpathSApply(doc, "//div[@id=gs_ab_md]", xmlValue)
 h2 <- strsplit(h1, " ")[[1]][2] 
 num <- as.integer(sub("[[:punct:]]", "", h2))
 cat(" Number of hits: ", num, " ---- ", "If this number is far from the returned results something might have gone wrong.. ", sep = "")
 
 # If there are no results, stop and throw an error message:
 if (num == 0 | is.na(num)) {
 stop(" ...There is no result for the submitted search string!")
 }
 
 pages.max <- ceiling(num/100)
 
 # start as used in URL:
 start <- 100 * 1:pages.max - 100
 
 # Collect URLs as list:
 URLs <- paste("http://scholar.google.com/scholar?start=", start, "&q=", input, 
 "&num=100&as_sdt=1,5&as_vis=", citation, "&as_ylo=", since, sep = "")
 
 scraper_internal <- function(x) {
 
 doc <- htmlParse(x, encoding="UTF-8")
 
 # titles:
 tit <- xpathSApply(doc, "//h3[@class=gs_rt]", xmlValue)
 
 # publication:
 pub <- xpathSApply(doc, "//div[@class=gs_a]", xmlValue)
 
 # links:
 lin <- xpathSApply(doc, "//h3[@class=gs_rt]/a", xmlAttrs)
 
 # summaries are truncated, and thus wont be used.. 
 # abst <- xpathSApply(doc, //div[@class=gs_rs], xmlValue)
 # ..to be extended for individual needs
 options(warn=(-1))
 dat <- data.frame(TITLES = tit, PUBLICATION = pub, 
 YEAR = as.integer(gsub(".*s(d{4})s.*", "1", pub)),
 LINKS = lin)
 options(warn=0)
 return(dat)
 }

 result <- do.call("rbind", lapply(URLs, scraper_internal))
 if (write == T) {
 result$LINKS <- paste("=Hyperlink(",""", result$LINKS, """, ")", sep = "")
 write.table(result, "GScholar_Output.CSV", sep = ";", 
 row.names = F, quote = F)
 shell.exec("GScholar_Output.CSV") 
 } else {
 return(result)
 }
}

# EXAMPLE:

input <- "allintitle:amphibian+diversity"
df <- GScholar_Scraper(input, since = 1980, citation = 1)

#install.packages("tm")
library(tm)

#install.packages("wordcloud")
library(wordcloud)

corpus <- Corpus(VectorSource(df$TITLES))
corpus <- tm_map(corpus, function(x)removeWords(x, c(stopwords(), "PDF", "B", "DOC", "HTML", "BOOK", "CITATION")))
corpus <- tm_map(corpus, removePunctuation)
tdm <- TermDocumentMatrix(corpus)
m <- as.matrix(tdm)
v <- sort(rowSums(m), decreasing = TRUE)
d <- data.frame(word = names(v), freq = v)

# remove numbers from strings:
d <- d[-grep("[0-9]", d$word), ]

# print wordcloud:
wordcloud(d$word, d$freq)

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