Hello, Jorge!
This might help:
> fish.df
Sex Length
1 male 15
2 fema 20
3 fema 17
4 fema 19
5 male 18
> str(fish.df)
'data.frame': 5 obs. of 2 variables:
$ Sex : Factor w/ 2 levels "fema","male": 2 1 1 1 2
$ Length: int 15 20 17 19 18
> tapply(fish.df$Length,fish.df$Sex,mean)
fema male
18.66667 16.50000
>
Sincerely,
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: [EMAIL PROTECTED]
From: "Jorge Cornejo Donoso" <[EMAIL PROTECTED]>
Subject: [R] RV: By sentence
Hi dear listers
Do you know how to made a mean by one or more categorical variables?
I can do that quite easy on SAS by in R I just can't do it E.g.
Some fishes
Sex Lenght
male 15
fema 20
fema 17
fema 19
male 18
So the idea is mean(Lenght) by sex, in order to have sex: Male
mean=XX Sex: Fema mean=YY
In this case is quite easy to do it by a loop, but I have a huge DB
so is not an option. Any suggestion?
Thanks in advance!
--
Jorge Cornejo Donoso
Universidad Austral de Chile
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