On May 19, 2012, at 5:00 PM, Sparks, John James wrote:
Dear R Helpers,
I am getting an error message from the try function that I don't
understand so I am hoping that someone can help.
I am scraping from web pages, but sometimes they disappear. When that
happens I need to control for it with some sort of function.
This web page is parsed without a problem.
exh<-"NASDAQ"
tic<-"EGHT"
URL<-paste("http://www.advfn.com/p.php?pid=financials&btn=istart_date&mode=quarterly_reports&symbol=
",
exh,"%3A",tic,"&istart_date=0", sep = "")
doc <- htmlParse(URL)
However, when I change the value of tic it will not.
tic<-"AACOU"
URL<-paste("http://www.advfn.com/p.php?pid=financials&btn=istart_date&mode=quarterly_reports&symbol=
",
exh,"%3A",tic,"&istart_date=0", sep = "")
doc <- htmlParse(URL)
Error in htmlParse(URL) :
error in creating parser for
http://www.advfn.com/p.php?pid=financials&btn=istart_date&mode=quarterly_reports&symbol=NASDAQ0X1.CP-1072AACOU&istart_date=0
I tried to account for this using the try function but I get the error
below that I don't understand.
options(error = expression(NULL))
URL<-paste("http://www.advfn.com/p.php?pid=financials&btn=istart_date&mode=quarterly_reports&symbol=
",
exh,"%3A",tic,"&istart_date=0", sep = "")
if(
!is(
try(
doc <- htmlParse(URL)
,"try-error")
)
)
{
qtrstop <- xpathApply(doc, "count(//select/option)")-5
}
Error in !silent : invalid argument type
Generally one needs to test for inherits(try(...), "try-error")
See last example in ?try
--
David
Any help would be most appreciated.
--John Sparks
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
