conditional selection with Factors

Hi All,

I want to select a level of a factor variable from a dataset. I have
the folowing data: dataset: use factor: month (use$month,
levels=February, July) > use[1:5,]
     month registration use  department size
1 February     KKG151GP   Y      Safety  1.6
To select February I tried:

use[use$month=="February"]

Error in "[.data.frame"(use, use$month == "February") : 
        undefined columns selected

use[use$month == levels(use$month)[1]]

Error in "[.data.frame"(use, use$month == levels(use$month)[1]) : 
        undefined columns selected
It seems if a logical variable is created, and the subsetting on a
factor variable won't work directly.(It works directly for numeric
variables)  Can anyone help please.

Regards
Hennie Gerber


Hennie Gerber
Statistician
UNISA - Research Support
+ 27 12 429 3188
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