[R] would you give me your hand to standardize columns in a matrix?

[arun]

Hi,
you could use scale()

test[,3:4]<-scale(test[,3:4])
> test
     X Y       temp        oxy
[1,] 1 4  0.9408239  1.1264280
[2,] 2 5 -1.0772720  0.1277835
[3,] 3 6 -0.6679277  0.9009276
[4,] 4 7  0.2795755 -1.0287112
[5,] 5 8  1.3329929  0.2147622
[6,] 6 9 -0.8081926 -1.3411902


A.K.



----- Original Message -----
From: Kristi Glover <kristi.glover at hotmail.com>
To: R-help <r-help at r-project.org>
Cc: 
Sent: Thursday, June 28, 2012 3:11 PM
Subject: [R] would you give me your hand to standardize columns in a matrix?


Hi R User,
Would you give me your hand to standardize some columns in a matrix? 

I have included the example table. 

> dput(test)
structure(list(X = c(1, 2, 3, 4, 5, 6), Y = c(4, 5, 6, 7, 8, 
9), temp = c(0.818, 0.113, 0.256, 0.587, 0.955, 0.207), oxy = c(0.797, 
0.487, 0.727, 0.128, 0.514, 0.031)), .Names = c("X", "Y", "temp", 
"oxy"), row.names = c(NA, -6L), class = "data.frame")

here I wanted to standardize the variable "temp" and "oxy". I have more than 75 variables so that I need to apply 'loop'. 

Could you help me to make a loop?

I wrote following but, it did not work. 

for (i in 1:n(test)){
for (t in 1:T (test)) x.z[i] = (x[i,t] - mean(x(i,]/sd)x[i,])
}

Thanks for your help.

Kristi

                          
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