[R] splitting data frame based on a criteria

[Moshe Olshansky]

Also check ?aggregate


--- On Wed, 4/6/08, Ingmar Visser <i.visser at uva.nl> wrote:

> From: Ingmar Visser <i.visser at uva.nl>
> Subject: Re: [R] splitting data frame based on a criteria
> To: "Marvin Lists" <marvin.lists at gmail.com>
> Cc: r-help at r-project.org
> Received: Wednesday, 4 June, 2008, 5:11 AM
> ?by may be helpful here
> eg if dat is your data.frame and yf is a factor (created
> using ifelse)
> use by(dat,yf,mean) to compute the means for each level of
> yf
> hth, Ingmar
> 
> On Jun 3, 2008, at 8:37 PM, Marvin Lists wrote:
> 
> > Hi,
> > I have a data frame that I want to split into two
> based on the  
> > values of a
> > variable in it.
> >
> > The variable Y has numeric values ranging between 0
> through 70. I  
> > want to
> > plot the frequencies of another variable X in two
> different cases:
> > - When Y = 0 and
> > - When Y > 0
> >
> > How does one go about doing this?
> >
> > In general, I want to do several analyses with this
> data frame that  
> > are a
> > variation of the above situation, i.e. they require
> splitting the  
> > data into
> > different age, gender etc. and then calculating
> separate means,  
> > correlations
> > and so on for the different groups into which the data
> frame would  
> > split.
> >
> > I am struggling with the correct syntax for achieving
> this.
> >
> > Reading through the documentation suggests that tapply
> and split  
> > may be the
> > functions to use for my purposes but the examples in
> the  
> > documentations
> > didn't help me understand how I could achieve
> this.
> >
> > I would appreciate any suggestions and help.
> >
> > Thanks,
> > Marvin
> >
> > 	[[alternative HTML version deleted]]
> >
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> 
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained,
> reproducible code.