[R] data transformation using gamma

[Patrizio Frederic]

Roslina,
this code performs what you need:

dt	= matrix((1:(58*12))/58/12,58) # some numbers
# if dt is a data.frame use dt = as.matrix(dt)
a	= (1:12)/12 # some a coef
b	= (12:1)/12 # some b coef
dtgam	= matrix(pgamma(dt,a,b),58)
# dtgam is the transformation you're looking for

no loop needed no transform function involved
cheers,

Patrizio


2009/5/7 Roslina Zakaria <zroslina at yahoo.com>:
> Hi R-users,
>
> I have this code to uniformise the data using gamma:
>
>> length(dp1)
> [1] 696
>> dim(dp1)
> [1] 58 12
>> dim(ahall)
> [1]  1 12
>> dim(bhall)
> [1]  1 12
>
>> trans_dt <- function(dt,a,b)
> + { n1 <- ncol(dt)
> +   n2 <- length(dt)
> +   trans  <- vector(mode='numeric', length=n2)
> +   dim(trans) <- dim(dt)
> +   for (i in 1:n1)
> +   {  dt[,i] <- as.vector(dt[,i])
> +      trans[,i] <- transform(dti,newdt=pgamma(dti,shape= a[1,i],scale=b[1,i])) }
> +   trans
> + }
>
>> trans_dt(dp1,ahall,bhall)
> Error in transform(dti, newdt = pgamma(dti, shape = a[1, i], scale = b[1,  :
>   object "dti" not found
>
> and also try
> trans_dt <- function(dt,a,b)
> { n1 <- ncol(dt)
>   n2 <- length(dt)
>   trans  <- vector(mode='numeric', length=n2)
>   dim(trans) <- dim(dt)
>   for (i in 1:n1)
>   {  dti <- dt[,i]
>      ai  <- a[1,i]
>      bi  <- b[1,i]
>      trans[,i] <- transform(dti,newdt=pgamma(dti,shape= ai,scale=bi)) }
>   trans
> }
>
> trans_dt(dp1,ahall,bhall)
> Error in pgamma(dti, shape = ai, scale = bi) : object "dti" not found
>
>
> Thank you for any help given.
>
>
>
>        [[alternative HTML version deleted]]
>
>
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>
>



-- 
+-------------------------------------------------
| Patrizio Frederic, PhD
| Assistant Professor,
| Department of Economics,
| University of Modena and Reggio Emilia,
| Via Berengario 51,
| 41100 Modena, Italy
|
| tel:  +39 059 205 6727
| fax:  +39 059 205 6947
| mail: patrizio.frederic at unimore.it
+-------------------------------------------------