backtransform `scale()` for plotting

Question

I have a explanatory variable that is centered using scale() that is used to predict a response variable:

d <- data.frame(
  x=runif(100),
           


        

Answer 1

For a data frame or matrix:

set.seed(1)
x = matrix(sample(1:12), ncol= 3)
xs = scale(x, center = TRUE, scale = TRUE)

x.orig = t(apply(xs, 1, function(r)r*attr(xs,'scaled:scale') + attr(xs, 'scaled:center')))

print(x)
     [,1] [,2] [,3]
[1,]    4    2    3
[2,]    5    7    1
[3,]    6   10   11
[4,]    9   12    8

print(x.orig)
     [,1] [,2] [,3]
[1,]    4    2    3
[2,]    5    7    1
[3,]    6   10   11
[4,]    9   12    8

Be careful when using functions like identical():

print(x - x.orig)
     [,1] [,2]         [,3]
[1,]    0    0 0.000000e+00
[2,]    0    0 8.881784e-16
[3,]    0    0 0.000000e+00
[4,]    0    0 0.000000e+00

identical(x, x.orig)
# FALSE