Unable to resolve an Argument is of length zero error error

Question

I get an Argument is of length zero error when I run the below code

The code is from this blog - http://giventhedata.blogspot.in/2012/08/r-and-web-for-beginners-part-iii.html .

library(XML)
url<- "http://news.bbc.co.uk/2/hi/uk_politics/8044207.stm"
first<-"Abbott, Ms Diane"
url.tab <- readHTMLTable(url)
for (i in 1:length(url.tab)){
  if (as.character(url.tab[[i]][1,1]) == first ) {print(first)}
}

I know that the url.tab[[5]][1,1]) does contain the string "Abbott, Ms Diane", and when I run IF statement in isolation replacing the i with 5, it runs fine. Any help would be appreciated. I also tried declaring i<-1 upfront. DInt change anything.

Answer 1

Some of your tables are in fact NULL.

So you have to test for is.null before trying to subset the table:

for (i in 1:length(url.tab)){
  this.tab <- url.tab[[i]]
  if(!is.null(this.tab)) if(as.character(this.tab[1,1]) == first ) {print(first)}
}

[1] "Abbott, Ms Diane"