[R] Odp: question about "mean"

From: Petr PIKAL <petr.pikal_at_precheza.cz>
Date: Thu, 10 Jun 2010 10:44:46 +0200

Hi

split/sapply can be used besides other options

sapply(split(iris[,1:4], iris$Species), mean)

Regards
Petr

r-help-bounces_at_r-project.org napsal dne 10.06.2010 00:43:29:

> 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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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 - 08:47:16 GMT

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