[R] Looping until a solution is found

[John Poulsen]

Yes, it is wrapped around the code in mlefun, but could be changed...   
Thanks again, John.

David Winsemius wrote:
>
> On May 30, 2009, at 9:36 AM, Uwe Ligges wrote:
>>
>> John Poulsen wrote:
>>> Hello,
>>> I am using maximum likelihood to find the best parameters for a 
>>> model.  This involves sometimes tweaking the starting values to find 
>>> a solution that converges.
>>> I would like to automate the process so that when the optimizer runs 
>>> into an error it tweaks one of the parameters slightly, tries the 
>>> fit again, and then continues this until a solution if found.
>>> I have been using try() to test if a fit will work (see below), but 
>>> how do I run a loop that says continue until class(m1) is not "try 
>>> error"?
>>>  m1<-mlefun(startvals, data=data)
>>>
>>> if(class(m1)=="try-error"){startvals<-list(alpha=10,beta=1,loggamma=log(5),logk=log(exp(unlist(startvals[4]))+0.2))                  
>>> mlefun(starvals, data)}
>>>
>>
>> m1 <- mlefun(starvals, data=data)
>> while(class(m1) == "try-error"){
>>    startvals <- list(alpha=10, beta=1, loggamma=log(5),
>>                      logk=log(exp(unlist(startvals[4]))+0.2))
>>    m1 <- mlefun(starvals, data=data)
>> }
>>
>
> So this implicitly assumes that try() is wrapped around the code 
> inside mlefun?
>
>
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
>