R help - Jun 2004 - How to iterate through two objects of class "list" fast?

Hi!

I have 2 list objects
One list contains the data (list1) the second list2 contains the e.g linear
model for each element of list 1.
list2 <- lapply(list1,mylm,response) I obtain list 2 by something like this.

now I have a function myfunc  which takes an element from list1 and the
coresponding element from list2 does something and ....

list3[[x]] <- myfunc(list1[[x]],list2[[x]])

Until now I am runnign this in a for(x in 1:length(list1)) loop. But
"for" loops are slow especially if list3 is HUGE.

What can I do?

Sincerely
Eryk

"Wolski" <wolski at molgen.mpg.de> writes:
> list3[[x]] <- myfunc(list1[[x]],list2[[x]])
> 
> Until now I am runnign this in a for(x in 1:length(list1)) loop. But
"for" loops are slow especially if list3 is HUGE.
> 
> What can I do?
Use mapply(). I wouldn't expect the for loop to be all that slow
unless you have forgotten to allocate memory for the result list up
front, though.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907