[R] Multiple lapply get-around

Manoj - Hachibushu Capital Wanzare at HCJP.com
Mon Aug 30 15:45:25 CEST 2004

>	Do some calculation based on Fij
> 			Store Xi,Yj	= Fij

To clarify the above two lines: Do some processing for each f for each j and i and store the results in a three dimensional matrix format of i,j,f.

As you would have noticed, the outermost loop is the slowest moving one.



-----Original Message-----
From: Liaw, Andy [mailto:andy_liaw at merck.com]
Sent: Monday, August 30, 2004 9:07 PM
To: Manoj - Hachibushu Capital; r-help at stat.math.ethz.ch
Subject: RE: [R] Multiple lapply get-around

> From: Manoj - Hachibushu Capital
> I am faced with a situation wherein I have to use multiple 
> lapply's. The
> pseudo-code could be approximated to something as below:
> For each X from i=1 to n
> 	For each Y based on j=1 to m 
> 		For each F from 1 to f
> 			Do some calculation based on Fij
> 			Store Xi,Yj	= Fij

What does the line above mean?  Are you assigning the value of Fij to _both_
Xi and Yj?  Doesn't quite make sense to me...


> 		End For F
> 	End for Y
> End for X
> Is there anyway to optimize the processing logic further? I *guess*
> using the multiple lapply already optimizes the logic a little bit but
> is there anything else that could be done (apart from the obvious
> solution of writing a c-code)?
> Manoj
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