[R] [as.numeric]Convert Category data to Numeric Data

[arun]

Hi,
as.numeric(iris$Species)


iris1 <- within(iris,Species <-as.numeric(Species))
A.K.


I have a small question for converting the category data to numeric data. 

For example, if we use the iris data in r. we have: 

str(iris) 
'data.frame':	150 obs. of  5 variables: 
 $ Sepal.Length: num  5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ... 
 $ Sepal.Width : num  3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ... 
 $ Petal.Length: num  1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ... 
 $ Petal.Width : num  0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ... 
 $ Species     : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ... 
> head(iris) 
  Sepal.Length Sepal.Width Petal.Length Petal.Width Species 
1          5.1         3.5          1.4         0.2  setosa 
2          4.9         3.0          1.4         0.2  setosa 
3          4.7         3.2          1.3         0.2  setosa 
4          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 

And I would like to convert the last variable, Species, to numeric number. 

For example, 'setosa'=1, and "versicolor"=2, other=3. 

What code should I use? Here is my result from as.numeric(iris): 

> as.numeric(iris) 
Error: (list) object cannot be coerced to type 'double'