R help - Jul 2009 - while( ) to get a vector until the sum of elements are <= X ?

I have a vector of values

 

X = seq(1:10)

 

I want to get another vector V of with sample (with replacement) of X but
with a constrain:  V will have as much elements as those necessary to V sum
exactly 10.

 

If the N-th value of V make the sum greater than 10, it's is subtracted with
the difference to achieve the constrain.

 

I don't know how to achieve this. with a while?

 

____________

Paulo E. Cardoso

 


	[[alternative HTML version deleted]]

Hi

r-help-bounces at r-project.org napsal dne 10.07.2009 12:07:03:
> I have a vector of values
> 
> 
> 
> X = seq(1:10)
> 
> 
> 
> I want to get another vector V of with sample (with replacement) of X 
but
> with a constrain:  V will have as much elements as those necessary to V 
sum
> exactly 10.
> 
> 
> 
> If the N-th value of V make the sum greater than 10, it's is subtracted
with
> the difference to achieve the constrain.
> 
> 
> 
> I don't know how to achieve this. with a while?
Maybe.

X = seq(1:10)

fff <- function(x, threshold=10) {
v<- sample(X, replace=T)
v.<-cumsum(v)
logic <- v. <= threshold
difer <- 10-sum(v[logic])
if (difer>0) c(v[logic], difer) else v[logic]
}

Regards
Petr

> 
> 
> 
> ____________
> 
> Paulo E. Cardoso
> 
> 
> 
> 
>    [[alternative HTML version deleted]]
> 
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I'm trying to export a SPDF to a image. The original file, when imported
into R (JPG with rGDAL)  have dimension = 997x997. When I save as bmp the
image(spdf), i get a 672x672 image.

____________
Paulo E. Cardoso