[R] Scaling values 0-255 -> -1 , 1 - how can this be done?

[arun]

HI,
You could also use:
set.seed(5)
 x1<-data.frame(matrix(sample(0:255,80,replace=TRUE),ncol=10))
library(car)
 do.call(cbind,lapply(x1,function(x) x<-recode(x,"0:127.5=-1;127.6:255=1")))
#     X1 X2 X3 X4 X5 X6 X7 X8 X9 X10
#[1,] -1  1 -1 -1 -1  1  1 -1  1  -1
#[2,]  1 -1  1 -1 -1 -1  1 -1  1   1
#[3,]  1 -1  1 -1 -1  1 -1 -1  1  -1
#[4,] -1 -1  1  1 -1  1  1 -1 -1   1
#[5,] -1 -1  1 -1  1  1  1  1  1  -1
#[6,]  1  1  1  1  1  1  1 -1  1   1
#[7,]  1 -1 -1 -1 -1  1  1  1  1  -1
#[8,]  1 -1 -1 -1 -1 -1 -1  1  1  -1
A.K.




----- Original Message -----
From: Brian Feeny <bfeeny at me.com>
To: r-help at r-project.org
Cc: 
Sent: Wednesday, November 21, 2012 10:32 AM
Subject: [R] Scaling values 0-255 -> -1 , 1 - how can this be done?


I have a dataframe in which I have values 0-255, I wish to transpose them such that:

if value  > 127.5 value = 1
if value < 127.5 value = -1

I did something similar using the "binarize" function of the biclust package, this transforms my dataframe to 0 and 1 values, but I wish
to use -1 and 1 and looking for a way in R to do this.

Brian

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