[R] Do loop

[Thomas Lumley]

On Tue, 22 Apr 2003, N Dey wrote:

> Dear all,
>
> I am doing integration by using integrate(..) command
> of R.  Integrand is a function of parameters (say p).
> And I ahve to do the integration for p ranging from 10
> to 500 (eg p<-10*1:50). And I want to store the
> results in a table like.
>
> p	result
> 10	------
> 20	------
>
> Is there any easy way to do this. I was trying
> for(p<-10*1:50){integrate(Func, lower = 0, upper =
> 182)}, but some problem couldn't do it.
>
>
> > Func<-function(x,p){exp(2*x-(3*p/10))*exp(-(5*x))}
> > for(p in 10*1:50){integrate(Func, lower = 0, upper =
> 182)}
> Error in f(x, ...) : Argument "p" is missing, with no
> default

You need to pass the `p' argument.

One way is
 Func<-function(x,p){exp(2*x-(3*p/10))*exp(-(5*x))}
 results<-numeric(50)
 for(i in 1:50){
	result[i]<-integrate(Func,lower=0, upper=182,p=10*i)$value
}

More elegantly
 Func<-function(x,p){exp(2*x-(3*p/10))*exp(-(5*x))}
 results<-sapply(10*(1:50), function(p) integrate(Func,
				lower=0,upper=182,p=p)$value)



	-thomas