[R] readHTMLTable (XML package)

Ista Zahn istazahn at gmail.com
Wed Jan 16 00:18:13 CET 2013

Hi Dan,

On Tue, Jan 15, 2013 at 5:31 PM, Lopez, Dan <lopez235 at llnl.gov> wrote:
> Hi Ista,
> It does exist. It’s a page in our company intranet.

Ah, good.

> It is https so it looks like I can't use RCurl either. I tried RCurl BTW and got the below error.

Well that error is not because RCurl doesn't work with https protocol.
In my original example I meant to show

tabs <- readHTMLTable(getURL("https://en.wikipedia.org/wiki/List_of_countries_by_population"))

i.e., getURL() does work with https. (Well, maybe depending on your
version of libcurl. See the getURL help page for details.)

> Do you have experience with pulling a table of an https site?

Yes, I do :)

> If so how do I do that?

See below

>> tabs <- readHTMLTable(getURL("https://hr-workforce-analytics.llnl.gov/wf_pi_pop.html"))
> Error in readHTMLTable(getURL("https://hr-workforce-analytics.llnl.gov/wf_pi_pop.html")) :
>   error in evaluating the argument 'doc' in selecting a method for function 'readHTMLTable': Error in function (type, msg, asError = TRUE)  :
>   SSL certificate problem, verify that the CA cert is OK. Details:
> error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

This is an RCurl FAQ (see http://www.omegahat.org/RCurl/FAQ.html). The
quick and dirty way is

ssl.verifypeer = FALSE)

> Thanks.
> Dan
> -----Original Message-----
> From: Ista Zahn [mailto:istazahn at gmail.com]
> Sent: Tuesday, January 15, 2013 12:22 PM
> To: Lopez, Dan
> Cc: R help (r-help at r-project.org)
> Subject: Re: [R] readHTMLTable (XML package)
> Hi Dan,
> A couple of things: first, I think that file really does not exist (at least I can't open it in my web browser). Second, even if it did,
> url() cannot download from https, according to the details section of ?url, which points you to RCurl. So, once you verify that you url actually exists you can do something like
> library(XML)
> library(RCurl)
> tabs <- readHTMLTable(getURL("http://en.wikipedia.org/wiki/List_of_countries_by_population"))
> Best,
> Ista
> On Tue, Jan 15, 2013 at 2:59 PM, Lopez, Dan <lopez235 at llnl.gov> wrote:
>> Hi,
>> I am using XML::readHTMLTable and getting the below error. Does anyone know why? Does this function not work with https? I didn't see anything in help about that.
>>> library(XML)
>>> wampage<-readHTMLTable('https://hr-workforce-analytics.llnl.gov/wf_pi
>>> _pop.html',1)
>> Error in htmlParse(doc) :
>>   File https://hr-workforce-analytics.llnl.gov/wf_pi_pop.html does not
>> exist
>> Dan
>>         [[alternative HTML version deleted]]
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