Handling categorical variables in R

[fog37]

TL;DR Summary

Handling categorical variables in R

Hello R users,

My general understanding is that, in R, nominal categorical variables (with 2 or more levels) must be first converted into factors and THEN to dummy variables (k-1 dummy variables for k levels). Is that correct?

Once we accomplish categorical variable -> factor -> dummy variables, we can then use the dummy variable as an independent or dependent variable in a statistical model (P.S. : when using the function $lm()$ in R, the function $lm()$ automatically does the dummy variable conversion but I am not sure that being true for other models).

What if we converted the categorical variable to dummy variables without the intermediate factor step? Would that still work in R?

Python does not have factors so that intermediate "factor" step does not apply...

Thanks!

 

[Office_Shredder]

Can you give a code example? I'm not sure what the factor step is but seeing what's actually called might help.

 

[Dale]

TL;DR Summary: Handling categorical variables in R

What if we converted the categorical variable to dummy variables without the intermediate factor step? Would that still work in R?

I have never tried this, but from my experience I would think that yes you could do that. You would lose the ability to choose different contrasts, since that would be your dummy variables. But I don’t see why it wouldn’t work