[R] Extend my code to run several data at once.

Daniel Malter daniel at umd.edu
Sat Jul 23 23:43:30 CEST 2011


If you just want to apply the function over successive columns of a data
frame use

apply(name.of.data.frame, 2 , llik)

Daniel


EdBo wrote:
> 
> Hi
> 
> I have a code that calculate maximisation using optimx and it is working
> just fine. I want to extend the code to run several colomns of R_j where j
> runs from 1 to 200. If I am to run the code in its current state, it means
> I will have to run it 200 times manually. May you help me adjust it to
> accomodate several rows of R_j and print the 200 results.
> 
> ***Please do not get intimidated by the maths in the code.***
> 
> my code
> ######
> afull=read.table("D:/hope.txt",header=T)
> library(optimx) 
> llik = function(x) 
>    { 
>     al_j=x[1]; au_j=x[2]; sigma_j=x[3];  b_j=x[4]
>     sum(na.rm=T,
>         ifelse(a$R_j< 0, log(1 / ( sqrt(2*pi) * sigma_j) )-
>                            (1/( 2*sigma_j^2 ) ) * ( 
> (a$R_j+al_j-b_j*a$R_m)^2 ) , 
> 
>          ifelse(a$R_j>0 , log(1 / ( sqrt(2*pi) * sigma_j) )-
>                            (1/( 2*sigma_j^2 ) ) * ( 
> (a$R_j+al_j-b_j*a$R_m)^2 ) ,
> 
> 				log(ifelse (( pnorm (au_j, mean=b_j * a$R_m, sd= sqrt(sigma_j^2))-
>                            pnorm(al_j, mean=b_j * a$R_m, sd=sqrt
> (sigma_j^2)) ) > 0,
> 
> 					(pnorm (au_j,mean=b_j * a$R_m, sd= sqrt(sigma_j^2))-
>                            pnorm(al_j, mean=b_j * a$R_m, sd=
> sqrt(sigma_j^2) )),
> 					1) ) ) )
>       )
>    } 
> start.par = c(-0.01,0.01,0.1,1) 
> 
> #looping now
> runs=133/20+1
> 
> 
> out <- matrix(NA, nrow = runs, ncol = 4,
> 
> dimnames = list(paste("Qtr:", 1:runs , sep = ''),
> 
> c("al_j", "au_j", "sigma_j", "b_j"))) 
> 
>   
> ## Estimate parameters based on rows 0-20, 21-40, 41-60 of afull
> for (i in 1:runs) {
> 		index_start=20*(i-1)+1
> 		index_end= 20*i
>  		a=afull[index_start:index_end,]
> 		out[i, ] <- optimx(llik,par = start.par,method = "Nelder-Mead",
> control=list(maximize=TRUE) )[[1]][[1]]
> 		} 
> 
> ## Yields 
>> out
>                al_j        au_j     sigma_j        b_j
> Qtr:1  0.0012402032 0.001082986 0.012889809 1.14095125
> Qtr:2  0.0011302178 0.582718275 0.009376083 0.06615565
> Qtr:3  0.0013349347 0.417495301 0.013286103 0.60548903
> Qtr:4 -0.0016659441 0.162250321 0.015088915 0.67395511
> Qtr:5  0.0043159984 0.004315976 0.013153039 1.17341907
> Qtr:6  0.0027333033 0.527280348 0.018423347 0.53905153
> Qtr:7 -0.0009214064 0.749695104 0.008730072 0.02108032
>>
> 

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