great, exactly what I've being looking for !
thanks a lot !

2010/12/13 Duncan Murdoch <murdoch.duncan@gmail.com>

> On 13/12/2010 12:56 PM, Arthur Charpentier wrote:
>
>> sorry... localization is a string of characters
>> for instance
>> localization =
>> paste("http://www.resultsfromtennis.com/
>> ",year,"/atp/",city,".html",sep="")
>> where year is 2006 and city can be "wimbledon"
>> hence here, since the page
>> "http://www.resultsfromtennis.com/2007/atp/wimbledon.html" does exist, I
>> can get the tables inside
>> but
>> "http://www.resultsfromtennis.com/1977/atp/shertogenbosch.html"
>> does not exist... is there a way to detect that the html page does not
>> exist ?
>>
>
> If you try to read it and get an error, you will know there's a problem.
>  For example,
>
> x <- "http://cran.r-project.ogr"  # has a typo
> con <- url(x)
> html <- readLines(con)
>
> This should produce an error, but might give you a junk page if your DNS
> provider substitutes for it.  You can catch the error using
>
> html <- try(readLines(con), silent=TRUE)
> if (inherits(html, "try-error")) cat("Error!")
>
> Duncan Murdoch
>
>
>>
>> 2010/12/13 Duncan Murdoch <murdoch.duncan@gmail.com
>> <mailto:murdoch.duncan@gmail.com>>
>>
>>
>>    On 13/12/2010 12:36 PM, Arthur Charpentier wrote:
>>
>>        I was wondering if there was a function like "does connection
>>        exists" ?
>>
>>
>>    See ?showConnections.
>>
>>
>>        I am currently using loops to build up a database, and I have
>> either
>>
>>              B = getConnection(localization)
>>
>>        Error in getConnection(localization) : there is no connection
>>        -2147483648
>>        In addition: Warning message:
>>        In getConnection(localization) : NAs introduced by coercion
>>
>>
>>    Where did the localization variable come from?  getConnection is
>>    pretty rarely used.
>>
>>
>>
>>        or
>>
>>              B = scan(localization)
>>
>>        Error in file(file, "r") : cannot open the connection
>>        In addition: Warning message:
>>        In file(file, "r") : cannot open: HTTP status was '404 Not Found'
>>
>>        is there a way to test where localization is an html page, or
>>        not ? and to
>>        say that if localization does exist, then scan it ?
>>
>>
>>    What's your definition of an html page?  Testing for valid html is
>> hard.
>>
>>    Duncan Murdoch
>>
>>
>>
>

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