Re: [R] question about "mean"

From: Phil Spector <spector_at_stat.berkeley.edu>
Date: Wed, 09 Jun 2010 19:53:39 -0700 (PDT)

One possibility is

> aggregate(iris[,-5],list(iris[,5]),mean)

      Group.1 Sepal.Length Sepal.Width Petal.Length Petal.Width
1     setosa        5.006       3.428        1.462       0.246
2 versicolor        5.936       2.770        4.260       1.326
3  virginica        6.588       2.974        5.552       2.026

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector_at_stat.berkeley.edu


On Wed, 9 Jun 2010, SH.Chou wrote:

> Hi there:
> I have a question about generating mean value of a data.frame. Take
> iris data for example, if I have a data.frame looking like the following:
> ---------------------
> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
> 1 5.1 3.5 1.4
> 0.2 setosa
> 2 4.9 3.0 1.4
> 0.2 setosa
> 3 4.7 3.2 1.3
> 0.2 setosa
> . . . .
> . .
> . . . .
> . .
> . . . .
> . .
> -----------------------
> There are three different species in this table. I want to make a table and
> calculate mean value for each specie as the following table:

>

> -----------------
> Sepal.Length Sepal.Width Petal.Length
> Petal.Width
> mean.setosa 5.006 3.428 1.462
> 0.246
> mean.versicolor 5.936 2.770 4.260
> 1.326
> mean.virginica 6.588 2.974 5.552
> 2.026
> -----------------
> Is there any short syntax can do it?? I mean shorter than the code I wrote
> as following:
>

> attach(iris)
> mean.setosa<-mean(iris[Species=="setosa", 1:4])
> mean.versicolor<-mean(iris[Species=="versicolor", 1:4])
> mean.virginica<-mean(iris[Species=="virginica", 1:4])
> data.mean<-rbind(mean.setosa, mean.versicolor, mean.virginica)
> detach(iris)
> ------------------
>

> Thanks a million!!!
>
>

> --
> =====================================
> Shih-Hsiung, Chou
> System Administrator / PH.D Student at
> Department of Industrial Manufacturing
> and Systems Engineering
> Kansas State University
>

> [[alternative HTML version deleted]]
>
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R-help_at_r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu 10 Jun 2010 - 02:57:33 GMT

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