Hello R users,

I run this code under windows XP and R 2.7.1 :

> head(esoph)
  agegp     alcgp    tobgp ncases ncontrols
1 25-34 0-39g/day 0-9g/day      0        40
2 25-34 0-39g/day    10-19      0        10
3 25-34 0-39g/day    20-29      0         6
4 25-34 0-39g/day      30+      0         5
5 25-34     40-79 0-9g/day      0        27
6 25-34     40-79    10-19      0         7
> class(esoph$agegp)
[1] "ordered" "factor"
> class(esoph$alcgp)
[1] "ordered" "factor"
> class(esoph$tobgp)
[1] "ordered" "factor"
> class(esoph$ncases)
[1] "numeric"
> class(esoph$ncontrols)
[1] "numeric"
> apply(esoph, 2, class)
      agegp       alcgp       tobgp      ncases   ncontrols
"character" "character" "character" "character" "character"

I don't understand why the result is all "character"...

Thanks a lot.

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