[R] splitting data frame based on a criteria

[Petr PIKAL]

Hi

the other possible option is to use split with suitable graphing technique 
or with lapply and appropriate function
e.g.

boxplot(split(X, Y>0))
histogram( ~ X|Y)

gives Marvin 

r-help-bounces at r-project.org napsal dne 03.06.2008 21:11:29:

> ?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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> ______________________________________________
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