R help - Nov 2012 - Accumulate objects in list after try()

Hi,

I have written a function "harvest" and I would like to run the
function for
each value in a vector c(1:1000). The function returns 4 list objects
(obj_1, obj_3, obj_3, obj_4) using the following code at the end of the
function: return(list(obj_1 = obj_1, obj_2 = obj_2, obj_3 = obj_3, obj_4
obj_4)).

Since I am connecting with the web in the function and the connection
sometimes fails causing errors to occur, I invoke the function as follows:

for(i in 1:1000){
  result <- try(harvest(i));
  if(class(result) == "try-error") next;
  }

Everything works well accept for the fact that "result" only stores
obj_1,
obj_2, obj_3,  obj_4 for the last i in the loop. How do I store obj_1, 
obj_2, obj_3,  obj_4 for the first i in the first 4 elements of result, the
objects for the second i in the next 4 elements, etc?

Thank you very much.  





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Create an empty list called "result" before you run the loop.  Then
store
the results of the loop in the list.  For example:

result <- vector(mode="list", length=1000)
for(i in 1:1000){ 
        result[[i]] <- try(harvest(i))
        }

Jean



mdvaan <mathijsdevaan@gmail.com> wrote on 11/27/2012 12:09:38
AM:
> 
> Hi,
> 
> I have written a function "harvest" and I would like to run the
function
for
> each value in a vector c(1:1000). The function returns 4 list objects
> (obj_1, obj_3, obj_3, obj_4) using the following code at the end of the
> function: return(list(obj_1 = obj_1, obj_2 = obj_2, obj_3 = obj_3, obj_4 
> obj_4)).
> 
> Since I am connecting with the web in the function and the connection
> sometimes fails causing errors to occur, I invoke the function as 
follows:
> 
> for(i in 1:1000){
>   result <- try(harvest(i));
>   if(class(result) == "try-error") next;
>   }
> 
> Everything works well accept for the fact that "result" only
stores
obj_1, 
> obj_2, obj_3,  obj_4 for the last i in the loop. How do I store obj_1, 
> obj_2, obj_3,  obj_4 for the first i in the first 4 elements of result, 
the
> objects for the second i in the next 4 elements, etc?
> 
> Thank you very much. 
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