Columns of data.frame converted from numeric to character.

[Gerald.Jean@spgdag.ca]

Hello S-users,

S+2000, on NT5.0

I have a data.frame with all numeric columns, I convert one of the column
to character depending on the numeric values for that column, the whole
data.frame is converted to character mode, why?  Data.frames are lists and
as such can have columns of different modes, why is this happening in this
case and how do we prevent the conversion of the other columns?

> is.data.frame(ttt)
[1] T

> apply(ttt, 2, FUN =  mode)
     penet         n   success      pull         z      sign
 "numeric" "numeric" "numeric" "numeric" "numeric" "numeric"

> ttt[, 'sign'] <- ifelse(ttt[, 'sign'] == -1, '-',
+                            ifelse(ttt[, 'sign'] == 0, 'N', '+'))

> apply(ttt, 2, FUN =  mode)
       penet           n     success        pull           z        sign
 "character" "character" "character" "character" "character" "character"

> is.data.frame(ttt)
[1] T

Thanks to all,

Gérald Jean
Analyste-conseil (statistiques), Actuariat
télephone            : (418) 835-4900 poste (7639)
télecopieur          : (418) 835-6657
courrier électronique: gerald.jean@spgdag.ca

"In God we trust all others must bring data"