R help - Mar 2006 - vector conditional modification

dear R users
 
 
 I need to modify values in a vector, the modification needs to be based on a
matrix which define the from_index, to_index and a value.
 
 example:
 > x <- c(1, 0, 6, 3, 8, 9, 4, 3, 0)
 > m
   from   to   value
 1     2     3   5
 2     5     7   8
 3     9     9  11
 > 
 expected:
 1 5 5 3 8 8 8 3 11
 insert {R.utils} and append are too expensive and indirect for the task. 
 
 
 thank you
 
 
		
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> x <- c(1, 0, 6, 3, 8, 9, 4, 3, 0)
> m <- rbind(c(2,3,5), c(5,7,8), c(9,9,11))
> m
     [,1] [,2] [,3]
[1,]    2    3    5
[2,]    5    7    8
[3,]    9    9   11
> # create matrix of indices and values
> mI <- do.call('rbind', apply(m, 1, function(y)cbind(y[1]:y[2],
y[3])))
> mI
     [,1] [,2]
[1,]    2    5
[2,]    3    5
[3,]    5    8
[4,]    6    8
[5,]    7    8
[6,]    9   11
> # store new values
> x[mI[,1]] <- mI[,2]
> x
[1]  1  5  5  3  8  8  8  3 11
>
>

On 3/25/06, Fred J. <phddas@yahoo.com> wrote:
>
> dear R users
>
>
> I need to modify values in a vector, the modification needs to be based on
> a matrix which define the from_index, to_index and a value.
>
> example:
> > x <- c(1, 0, 6, 3, 8, 9, 4, 3, 0)
> > m
>   from   to   value
> 1     2     3   5
> 2     5     7   8
> 3     9     9  11
> >
> expected:
> 1 5 5 3 8 8 8 3 11
> insert {R.utils} and append are too expensive and indirect for the task.
>
>
> thank you
>
>
>
> ---------------------------------
>
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>
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>


--
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

What the problem you are trying to solve?

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