A little Problem in section 5.5.2 Factors

[alibalapour]

5.5.2 Factors :
"R uses the levels attribute when it displays the factor, as you will see. R will display each 1 as female, the first label in the levels vector, and each 2 as male, the second label. If the factor included 3s, they would be displayed as the third label, and so on: …"

It's wrong! Because if we add an object that start with a letter that's alphabetically before 'f' , for example starts with 'a' in 'another' , the labels of factor class will change. It will be :
'another' ---> 1
'female' ---> 2
'male' ---> 3
To be more obvious, I write this part of code:

gender <- factor(c("male", "female", "another", "female", "another", "male"))
unclass(gender)
## [1] 3 2 1 2 1 3
## attr(,"levels")
## [1] "another" "female"  "male"

You saw that the label of "another" is 1. That means the numbering of the factor is alphabetical.

sorry for my bad English. :)