R, tryCatch error

r, try-catch

Solution

I think your function has to have `cond` as an argument – at least that's how I've used `tryCatch()` in the past, and your error message seems to indicate it as the problem.

Try the following: `gethelp.df =tryCatch(htmlTreeParse(gethelp.url, useInternalNodes = T), error = function(cond) next)`

Note that the above line will still throw an error, b/c the example code is not in a loop. So I just replaced `next` with `NA`, and it worked fine.

Edit: In response to OP's comment, I suggest trying the following:

gethelp.df =tryCatch(htmlTreeParse(gethelp.url, useInternalNodes = T), error = function(cond)"skip")
if(gethelp.df=="skip"){next}

Problem

I am parsing alot of website and I wrote a script that loops thru the thousands of link from a separate file. However, I experienced that sometimes R couldn't load one link and it stops in the middle of loop, leaving many of other urls unparsed. So I tried to use tryCatch, so the script ignores this case and keep parsing next urls. However, I recently experienced that tryCatch generates below error. ``` gethelp.url = 'http://forums.autodesk.com/t5/Vault-General/bd-p/101' gethelp.df =tryCatch(htmlTreeParse(gethelp.url, useInternalNodes = T), error = function() next) Error in value[[3L]](cond) : unused argument (cond) Calls: withRestarts ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous> Execution halted ``` The confusing thing is sometimes it works well and sometimes it throws out this error message, even though the same script parses the same urls. Can anyone give me a guidance how to interpret this error messages? I read the document but i couldn't find much insights.

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