How can I use a loop to clear website data for multiple web pages in R?

Question

I would like to apply a loop to clear data from multiple web pages in R. I can clear data for a single web page, however, when I try to use a loop across multiple pages, I get a disappointing error. I spent a lot of time, but to no avail. Any help would be greatly appreciated.

It works:

###########################
# GET COUNTRY DATA
###########################

library("rvest")

site <- paste("http://www.countryreports.org/country/","Norway",".htm", sep="")
site <- html(site)

stats<-
    data.frame(names =site %>% html_nodes(xpath="//*/td[1]") %>% html_text() ,
         facts =site %>% html_nodes(xpath="//*/td[2]") %>% html_text() ,
         stringsAsFactors=FALSE)

stats$country <- "Norway"
stats$names   <- gsub('[\r\n\t]', '', stats$names)
stats$facts   <- gsub('[\r\n\t]', '', stats$facts)
View(stats)

However, when I try to write this in a loop, I get an error

###########################
# ATTEMPT IN A LOOP
###########################

country<-c("Norway","Sweden","Finland","France","Greece","Italy","Spain")

for(i in country){

site <- paste("http://www.countryreports.org/country/",country,".htm", sep="")
site <- html(site)

stats<-
data.frame(names =site %>% html_nodes(xpath="//*/td[1]") %>% html_text() ,
         facts =site %>% html_nodes(xpath="//*/td[2]") %>% html_text() ,
       stringsAsFactors=FALSE)

stats$country <- country
stats$names   <- gsub('[\r\n\t]', '', stats$names)
stats$facts   <- gsub('[\r\n\t]', '', stats$facts)

stats<-rbind(stats,stats)
stats<-stats[!duplicated(stats),]
}

Error:

Error: length(url) == 1 is not TRUE
In addition: Warning message:
In if (grepl("^http", x)) { :
  the condition has length > 1 and only the first element will be used

Answer 1

Final working code:

###########################
# THIS WORKS!!!!
###########################

country<-c("Norway","Sweden","Finland","France","Greece","Italy","Spain")

for(i in country){

site <- paste("http://www.countryreports.org/country/",i,".htm", sep="")
site <- html(site)

stats<-
data.frame(names =site %>% html_nodes(xpath="//*/td[1]") %>% html_text() ,
     facts =site %>% html_nodes(xpath="//*/td[2]") %>% html_text() ,
       stringsAsFactors=FALSE)

stats$nm <- i
stats$names   <- gsub('[\r\n\t]', '', stats$names)
stats$facts   <- gsub('[\r\n\t]', '', stats$facts)
#stats<-stats[!duplicated(stats),]
all<-rbind(all,stats)

}
 View(all)

Answer 2

Just initialize an empty data frame before the loop. I made this problem and the following code works fine for me.

country<-c("Norway","Sweden","Finland","France","Greece","Italy","Spain")
df <- data.frame(names = character(0),facts = character(0),nm = character(0))

for(i in country){

  site <- paste("http://www.countryreports.org/country/",i,".htm", sep="")
  site <- html(site)

  stats<-
    data.frame(names =site %>% html_nodes(xpath="//*/td[1]") %>% html_text() ,
               facts =site %>% html_nodes(xpath="//*/td[2]") %>% html_text() ,
               stringsAsFactors=FALSE)

  stats$nm <- i
  stats$names   <- gsub('[\r\n\t]', '', stats$names)
  stats$facts   <- gsub('[\r\n\t]', '', stats$facts)
  #stats<-stats[!duplicated(stats),]
  #all<-rbind(all,stats)
  df <- rbind(df, stats)
  #all <- merge(Output,stats)

}
View(df)

Answer 3

This is what I did. This is not the best solution, but you will get a way out. Also this is just a workaround. I do not recommend writing the output of the table to a file when the loop starts. Well. After exiting stats,

output<-rbind(stats,i)

and then write a table,

write.table(output, file = "D:\\Documents\\HTML\\Test of loop.csv", row.names = FALSE, append = TRUE, sep = ",")

#then close the loop
}

Good luck.