Re: [Rd] 0.5 != integrate(dnorm,0,20000) = 0
I'd suggest that the original sin here is calling some particular numerical integration routine 'integrate', which gives the user an illusory sense of power Functions have to be well-behaved in various ways for quadrature to work well, and you've got to expect things like > integrate(function(x)tan(x),0,pi) Error in integrate(function(x) tan(x), 0, pi) : roundoff error is detected in the extrapolation table <<< a 'good' error -- tells the user something's wrong > integrate(function(x)tan(x)^2,0,pi) 1751.054 with absolute error < 0 <<< oops > integrate(function(x)1/(x-pi/2)^2,0,pi) <<< the same > pole (analytically) Error in integrate(function(x) 1/(x - pi/2)^2, 0, pi) : <<< gets a useful error in this form non-finite function value But by that argument, I suppose you shouldn't call floating-point addition "+" :-) -s __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] errors in getconnection or scan
great, exactly what I've being looking for !
thanks a lot !
2010/12/13 Duncan Murdoch
> 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 > >
>>
>>
>>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
>>
>>
>>
>
[[alternative HTML version deleted]]
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Re: [Rd] errors in getconnection or scan
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 mailto:murdoch.dun...@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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Re: [Rd] errors in getconnection or scan
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
?
2010/12/13 Duncan Murdoch
> 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
>
[[alternative HTML version deleted]]
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Re: [Rd] errors in getconnection or scan
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 __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
[Rd] errors in getconnection or scan
I was wondering if there was a function like "does connection exists" ? 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 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 ? [[alternative HTML version deleted]] __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
