R help - Feb 2005 - how do I get means by factor?

I want the mean of a response variable for each level of a factor in a
data.frame.  How is this done?

	[[alternative HTML version deleted]]

tapply( x, f, mean )

maybe with

tapply( x, f, mean, na.rm=T )

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> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Chris
> Sent: Wednesday, February 23, 2005 10:38 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] how do I get means by factor?
> 
> 
> I want the mean of a response variable for each level of a 
> factor in a data.frame.  How is this done?
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
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Chris <grover2160 <at> metrocast.net> writes:

: 
: I want the mean of a response variable for each level of a factor in a
: data.frame.  How is this done?

In addition to the tapply suggestion already given you can use
summary in package Hmisc:

summary(y ~ f)