[R] PROBLEMS with In `[<-.factor`(`*tmp*`, (¿ORDERED FACTOR?)

[David Winsemius]

On May 29, 2012, at 11:01 AM, RBB wrote:

> HI!!!
>
> I have a table containing qualitative and quantitative data; one of  
> the
> columns contains  "Level of education", and the possibilities are  
> "none",
> "High school", "college"; I want to give the value 0 to "none", the  
> value 1
> to "High school", and 2 to "college", but I got the following error:
>
> In `[<-.factor`(`*tmp*`, educa = "college", value = 2) :
>  invalid factor level, NAs generated
>
>
> WHAT IS WRONG????? :S :S :S
>

Hard to say. Although we can be fairly sure you have a factor and that  
your do NOT have an R contingency table. If you really had a table it  
would be one thing. A dataframe is another thing and one that is much  
more common.

dfrm <- data.frame(lev=factor(c("none", "high", "low", "high", "low")))
 > dfrm
    lev
1 none
2 high
3  low
4 high
5  low

 > levels(dfrm$lev)<- 2:0
 > dfrm
   lev
1   0
2   2
3   1
4   2
5   1

Notice that a factor variable's levels are ordered alphabetically, so  
"high" < "low" < "none" and if you wnat the numbers to match up you  
need to mentally figure out the right order to make  the matching work  
properly.

(It would be better practice not to overwrite the levels of an  
existing factor, since that action makes it very easy to really hash  
up the data.
-- 
David.
>
> THANKS A LOT!!!!!!!!!!!!!!
>
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