[R] Sum by categorical variable

[vito muggeo]

If I understand correctly what you are looking for, see ?tapply.
Below there is a toy example

> NumVar<-runif(100) #continuous variable
> CategVar<-rbinom(100,1,.7) #unbalanced categorical variable
> table(CategVar)
CategVar
 0  1
33 67
> tapply(NumVar,CategVar,sum)
       0        1
15.17833 32.11759

sum can be replaced by any function including mean, median, and
user-defined.
best,
vito


----- Original Message -----
From: "De Amicis Fabrizio (G.I.T.)" <Fabrizio.DeAmicis at git.generali.ch>
To: "'r-help at lists.R-project.org'" <r-help at stat.math.ethz.ch>
Sent: Tuesday, May 06, 2003 4:08 PM
Subject: [R] Sum by categorical variable


> Dear R-list,
> I have two variables (numerical and categorical) and  would like to have
the
> sum (and maybe some other statistics) of the numerical variable by the
> categorical one.
> Can you help me,
> Thank you,
> Fabrizio
>
>
> ---------------------------------------------------------------
> Fabrizio De Amicis
>
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