[R] How to change variables in datasets automatically

[Liaw, Andy]

Try:

a <- data.frame(Sepal.Length=1:4, Sepal.Width=2:5,
                Petal.Length=3:6, Petal.Width=4:7, 
                Species=rep("rosa",4))
b <- iris[1:10,]
newtest.iris <- rbind(a,b)
names(newtest.iris) <- c("SL", "SW", "PL", "PW", "Class")
newtest.iris$Class <- as.numeric(newtest.iris$Class) - 1

HTH,
Andy


> From: 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
> 
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