is it what you want?
>dat<-data.frame(x=rnorm(10),y=rnorm(10),z=rnorm(10))
> my.form <- as.formula(y ~ x + z)
> my.form
y ~ x + z
> m<-model.frame(my.form,data=dat)
> model.extract(m,"response")
1 2 3 4 5 6 7
-0.3434826 1.0145622 -0.4749584 0.4018080 -0.3039126 -0.8180650 0.5455521
8 9 10
1.1460328 0.8038568 1.1092655
======= 2005-07-12 22:43:33 您在来信中写道：=======
>I have a formula from which I want to deduce the name of the response
>variable. One way of doing so is as follows:
>
>> my.form <- as.formula("y ~ x + z")
>> all.vars(my.form)[1]
>[1] "y"
>>
>
>Is there a better way and/or preferrred method of determining "y" from
>my.form than this one? In messing around with terms, I came up with:
>
>> all.vars(terms(my.form))[attr(terms(my.form), "response")]
>[1] "y"
>>
>
>But that seems too ugly to be best.
>
>Thanks,
>
>Dave Kane
>
>> R.version
> _
>platform i686-pc-linux-gnu
>arch i686
>os linux-gnu
>system i686, linux-gnu
>status
>major 2
>minor 1.0
>year 2005
>month 04
>day 18
>language R
>>
>
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= = = = = = = = = = = = = = = = = = = =
2005-07-12
------
Deparment of Sociology
Fudan University
Blog:http://sociology.yculblog.com
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