[R] Scaling data

[Peter Dalgaard]

Jim Lemon wrote:
> On 09/28/2009 07:55 PM, Dry, Jonathan R wrote:
>> Hello all
>>
>> I have a data frame representing a matrix of data.  For each of my
>> variables (rows) I want to scale the data between 0 (representing the
>> minimum value in that row) and 1 (representing the maximum value in
>> that row).  I was wondering if there is a simple function anywhere
>> that does this?
>>
>>    
> Hi Jonathan,
> There are a number of such functions, but a particularly easy one in
> your case is rescale. Baptiste has already mentioned the one in ggplot,
> so I'll plug mine in plotrix:
> 
> mat1<-matrix(sample(1:20,16),nrow=4)
> library(plotrix)
> t(apply(mat1,1,rescale,c(0,1)))
> 

Notice also that scale() will do it if you tickle it in the right places:

> x  <- rnorm(500)
> range(scale(x, min(x), diff(range(x))))
[1] 0 1


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