[R] Extracting a subset

[Silvano]

Hi,

I have a dataset with many variables and observations.
The variable Group has two levels: C and P,
the Month variable has four levels: 0, 1, 2 and 3.

I want to extract a subset of the variable Weight, 
considering only 1 and 3 levels for Months of the Group 
variable.

I tried the command subset but it did not work. Any 
suggestions?

Thanks,

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Silvano Cesar da Costa
Departamento de Estatística
Universidade Estadual de Londrina
Fone: 3371-4346