[R] Discriminant function analysis

[Tyler Smith]

On 2008-02-07, Birgit Lemcke <birgit.lemcke at systbot.uzh.ch> wrote:
>
> Am 06.02.2008 um 21:00 schrieb Tyler Smith:
>>
>>> My dataset contains variables of the classes factor and numeric. Is
>>> there another function that is able to handle this?
>>
>> The numeric variables are fine. The factor variables may have to be
>> recoded into dummy binary variables, I'm not sure if lda() will deal
>> with them properly otherwise.
>
> But aren´t binary variables also factors? Or is there another  
> variable class than factor or numeric?
> Do I have have to set the classe of the binaries as numeric?
>

There is no binary class in R, so you would have to use a numeric
field. For example:

| sample | factor_1 |
|--------+----------|
| A      | red      |
| B      | green    |
| C      | blue     |

becomes:

| sample | dummy_1 | dummy_2 |
|--------+---------+---------|
| A      |       1 |       0 |
| B      |       0 |       1 |
| C      |       0 |       0 |

R can deal with dummy_1 and dummy_2 as numeric vectors. The details
should be explained in a good reference on multivariate statistics
(I'm looking at Legendre and Legendre (1998) section 1.5.7 and 11.5).

HTH,

Tyler