[R] How to change variables in datasets automatically

[Muhammad Subianto]

Dear R-helpers,
Suppose I have a dataset,
 data(iris)
 a <- data.frame(Sepal.Length=c(1:4), Sepal.Width=c(2:5),
Petal.Length=c(3:6), Petal.Width=c(4:7), Species=rep("rosa",4))
 b <- iris[1:10,]
 newtest.iris <- rbind(a,b)
>  newtest.iris
   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1           1.0         2.0          3.0         4.0    rosa
2           2.0         3.0          4.0         5.0    rosa
3           3.0         4.0          5.0         6.0    rosa
4           4.0         5.0          6.0         7.0    rosa
11          5.1         3.5          1.4         0.2  setosa
21          4.9         3.0          1.4         0.2  setosa
31          4.7         3.2          1.3         0.2  setosa
41          4.6         3.1          1.5         0.2  setosa
5           5.0         3.6          1.4         0.2  setosa
6           5.4         3.9          1.7         0.4  setosa
7           4.6         3.4          1.4         0.3  setosa
8           5.0         3.4          1.5         0.2  setosa
9           4.4         2.9          1.4         0.2  setosa
10          4.9         3.1          1.5         0.1  setosa
 
I want to change each labels (variables) like: Sepal.Length=SL, Sepal.Width=SW,
Petal.Length=PL, Petal.Width=PW, and Species=Class. Then I want to
change each cell
in Species variable like rosa=0 and setosa=1. The result something like this,

>  NewIris
    SL  SW  PL  PW Class
1  1.0 2.0 3.0 4.0     0
2  2.0 3.0 4.0 5.0     0
3  3.0 4.0 5.0 6.0     0
4  4.0 5.0 6.0 7.0     0
5  5.1 3.5 1.4 0.2     1
6  4.9 3.0 1.4 0.2     1
7  4.7 3.2 1.3 0.2     1
8  4.6 3.1 1.5 0.2     1
9  5.0 3.6 1.4 0.2     1
10 5.4 3.9 1.7 0.4     1
11 4.6 3.4 1.4 0.3     1
12 5.0 3.4 1.5 0.2     1
13 4.4 2.9 1.4 0.2     1
14 4.9 3.1 1.5 0.1     1
> 
I can do it the result above like this,

>  Class <- ifelse(newtest.iris$Species=="rosa", 0, 1) 
>  NewIris <- data.frame(SL = newtest.iris$Sepal.Length,
+                        SW = newtest.iris$Sepal.Width,
+                        PL = newtest.iris$Petal.Length,
+                        PW = newtest.iris$Petal.Width,
+                        Class)

Because I have more variables in my datasets which I must to change.
Is there any way to change automatically and which library contains a
function to compute that?
I  would be very happy if anyone could help me.
Thank you very much in advance.

Kindly regards, 
Muhammad Subianto