[R] how to apply two or more functions to each columns in a time?

[Pete Brecknock]

Yao He wrote
> Dear All:
> 
> I want to calculate the mean and sd for each column in a data.frame.
> 
> Taking data(iris) for example:
> I tried sapply(iris[,-5],mean,na.rm=T) or sapply(iris[,-5],sd,na.rm=T)
> to calculate the mean and sd .But sapply() transfer a function per
> time. How to transfer two functions in a time to generate a data.frame
> like this:
> 
>            Sepal.Length Sepal.Width Petal.Length Petal.Width
> mean    5.84333        3.05733        3.758000      1.199333
> SD        0.82806        0.43586        1.765298       0.762237
> 
> 
> Thanks a lot
> 
> Yao He
> 
> -- 
> —————————————————————————
> Master candidate in 2rd year
> Department of Animal genetics & breeding
> Room 436,College of Animial Science&Technology,
> China Agriculture University,Beijing,100193
> E-mail: 

> yao.h.1988@

> ——————————————————————————
> 
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Or maybe using apply ....

# data
d <- iris[,-5]

# apply function
a <-data.frame(apply(d, 2, function(x) c(mean=mean(x), sd=sd(x))))

# print(a) output
     Sepal.Length Sepal.Width Petal.Length Petal.Width
mean    5.8433333   3.0573333     3.758000   1.1993333
sd      0.8280661   0.4358663     1.765298   0.7622377

HTH

Pete





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