Argument is of length zero

r

Solution

As @gsee mentioned, you need to check that `symbol` isn't `NULL` before you check its value. Here's a minor update to your code that works (at least for George).

df = ldply(
  links, 
  function(x) 
  {
    text = xmlValue(x)
    if (!nzchar(text)) text = NULL
    symbol = xmlGetAttr(x, 'class')
    if (!is.null(symbol) && symbol != 'role') symbol = NULL
    if(!is.null(text) & !is.null(symbol))
      data.frame(symbol, text)         
  } 
)

Problem

I am trying to use the following syntax to get the occupation information from George Clooney's wikipedia page. Eventually I would like there to be a loop to get data on various personalitys' occupations. However, I get the following problem running the below code: ``` Error in if (symbol != "role") symbol = NULL : argument is of length zero ``` I am not sure why this keeps on coming up. ``` library(XML) library(plyr) url = 'http://en.wikipedia.org/wiki/George_Clooney' # don't forget to parse the HTML, doh! doc = htmlParse(url) # get every link in a table cell: links = getNodeSet(doc, '//table/tr/td') # make a data.frame for each node with non-blank text, link, and 'title' attribute: df = ldply(links, function(x) { text = xmlValue(x) if (text=='') text=NULL symbol = xmlGetAttr(x, 'class') if (symbol!='role') symbol=NULL if(!is.null(text) & !is.null(symbol)) data.frame(symbol, text) } ) ```

Original source