[R] Multiple lapply get-around

[james.holtman@convergys.com]

Try the following using 'lapply' and 'outer':

> myFuncs <- list(sin,sqrt)   # list of functions to evaluate
> lapply(myFuncs, function(func){   # apply to each function
+ outer(1:5, 1:5, function(x,y,func){     # here are the dimensions of x &
y
+ func(x+y)
+ }, func=func)
+ })
[[1]]
           [,1]       [,2]       [,3]       [,4]       [,5]
[1,]  0.9092974  0.1411200 -0.7568025 -0.9589243 -0.2794155
[2,]  0.1411200 -0.7568025 -0.9589243 -0.2794155  0.6569866
[3,] -0.7568025 -0.9589243 -0.2794155  0.6569866  0.9893582
[4,] -0.9589243 -0.2794155  0.6569866  0.9893582  0.4121185
[5,] -0.2794155  0.6569866  0.9893582  0.4121185 -0.5440211

[[2]]
         [,1]     [,2]     [,3]     [,4]     [,5]
[1,] 1.414214 1.732051 2.000000 2.236068 2.449490
[2,] 1.732051 2.000000 2.236068 2.449490 2.645751
[3,] 2.000000 2.236068 2.449490 2.645751 2.828427
[4,] 2.236068 2.449490 2.645751 2.828427 3.000000
[5,] 2.449490 2.645751 2.828427 3.000000 3.162278

__________________________________________________________
James Holtman        "What is the problem you are trying to solve?"
Executive Technical Consultant  --  Office of Technology, Convergys
james.holtman at convergys.com
+1 (513) 723-2929


                                                                                                                                          
                      "Manoj - Hachibushu                                                                                                 
                      Capital"                     To:       "Liaw, Andy" <andy_liaw at merck.com>, <r-help at stat.math.ethz.ch>               
                      <Wanzare at hcjp.com>           cc:                                                                                    
                      Sent by:                     Subject:  RE: [R] Multiple lapply get-around                                           
                      r-help-bounces at stat.m                                                                                               
                      ath.ethz.ch                                                                                                         
                                                                                                                                          
                                                                                                                                          
                      08/30/2004 09:45                                                                                                    
                                                                                                                                          
                                                                                                                                          




>            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.

HTH

Manoj

-----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...

Andy

>                        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)?
>
> TIA
>
> Manoj
>
> ______________________________________________
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