On Thu, 25 Dec 2008, Oliver Bandel wrote:
Bert Gunter gunter.berton at gene.com writes:
FWIW:
Good advice below! -- after all, the first rule of optimizing code is:
Don't!
For the record (yet again), the apply() family of functions (and their
packaged derivatives, of course) are merely
Prof Brian Ripley wrote:
On Thu, 25 Dec 2008, Oliver Bandel wrote:
The apply-functions do bring speed-advantages.
This is not only what I read about it,
I have used the apply-functions and really got
results faster.
The reason is simple: an apply-function does
make in C, what otherwise
Thankyou for the clarification, Brian. This is very helpful (as usual).
However, I think the important point, which I misstated, is that whether it
be for() or, e.g. lapply(), the loop contents must be evaluated at the
interpreted R level, and this is where most time is typically spent. To get
On Fri, 26 Dec 2008, Bert Gunter wrote:
Thankyou for the clarification, Brian. This is very helpful (as usual).
However, I think the important point, which I misstated, is that whether it
be for() or, e.g. lapply(), the loop contents must be evaluated at the
interpreted R level, and this is
I have used some of your advice in making some changes to my function and
function call before reposting.
Instead of nesting many 'for' loops, I have gotten to the point where I only
have one.(Also, please note, I am pasting the function calcProfit at the
end of this message as it is a bit
On Dec 23, 2008, at 9:55 AM, Brigid Mooney wrote:
I have used some of your advice in making some changes to my
function and function call before reposting.
Instead of nesting many 'for' loops, I have gotten to the point
where I only have one.(Also, please note, I am pasting the
Thank you again for your help.
I updated the parsing at the beginning of the calcProfit function with:
if (class(IterParam) == numeric)
{
long - IterParam[long]
short - IterParam[short]
investment - IterParam[investment]
stoploss - IterParam[stoploss]
On Dec 23, 2008, at 10:56 AM, Brigid Mooney wrote:
Thank you again for your help.
snip
-
With the 'apply' call, Results2 is of class list.
Results2 - apply(CombParam, 1, calcProfit, X, Y)
--
Problem Description: (reproducible code below)
Avoiding multiple nested for loops (as requested in the subject) is usually
a good idea, especially if you can take advantage of vectorized functions.
You were able redesign your code to use a single for loop. I presume there
was a substantial improvement in program speed. How much additional
I have to agree with Daniel Nordlund regarding not creating subsidiary
problems when the main problem has been cracked. Nonetheless, ...
might you be happier with the result of changing the last data.frame()
call in calcProfit to c()?
I get a matrix:
str(Results2)
num [1:14, 1:16]
On Mon, 22 Dec 2008, Brigid Mooney wrote:
Hi All,
I'm still pretty new to using R - and I was hoping I might be able to get
some advice as to how to use 'apply' or a similar function instead of using
nested for loops.
Unfortunately, you have given nothing that is reproducible.
The details
Hi All,
I'm still pretty new to using R - and I was hoping I might be able to get
some advice as to how to use 'apply' or a similar function instead of using
nested for loops.
Right now I have a script which uses nested for loops similar to this:
i - 1
for(a in Alpha) { for (b in Beta) { for (c
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