[R] By sentence

[Erin Hodgess]

Hi again!

Please try something like this:

> zone1.df
  zone  sex len
1    1 male  15
2    1 fema  20
3    1 fema  17
4    2 fema  19
5    2 male  18
> str(zone1.df)
'data.frame':   5 obs. of  3 variables:
 $ zone: Factor w/ 2 levels "1","2": 1 1 1 2 2
 $ sex : Factor w/ 2 levels "fema","male": 2 1 1 1 2
 $ len : int  15 20 17 19 18
> tapply(zone1.df$len,zone1.df[,-3],mean)
    sex
zone fema male
   1 18.5   15
   2 19.0   18
> 

Hope this helps!

Sincerely,
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: hodgess at gator.uhd.edu



From: "Jorge Cornejo-Donoso" <jorgecornejo at uach.cl>
To: "'Erin Hodgess'" <hodgess at gator.dt.uh.edu>
Subject: RE: [R]  RV: by sentence




OK.. Thank for the advice.
	By and tapply works with 1 categorical variable, but what can be
used for 2 categorical variables. Example:
Zone   Sex Length
1 	male     15
1	fema     20
1 	fema     17
2	fema     19
2 	male     18

The idea is to get the means by sex in each zone!

Thank in advance!

--

Jorge Cornejo Donoso

Universidad Austral de Chile

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