Hi Zhihua,

M <- data.frame (x=c(10, 13, 8, 11), y=c('A', 'B', 'A', 'A'))
which (M$x >= 10 & M$y == 'A')
# [1] 1 4

Hope it helps,
Nael

2008/3/7 N. Lapidus <n.lapidus@gmail.com>:

> Hi Zhihua,
>
> M <- data.frame (x=c(10, 13, 8, 11), y=c('A', 'B', 'A', 'A'))
> which (M$x >= 10 & M$y == 'A')
> # [1] 1 4
>
> Hope it helps,
> Nael
>
>
> 2008/3/7 zhihuali <lzhtom@hotmail.com>:
>
> >
> > Hi, netters,
> >
> > This is probably a rookie question but I couldn't find the answer after
> > hours of searching and trying.
> >
> > Suppose there'a a dataframe M:
> >
> > x     y
> > 10   A
> > 13   B
> > 8     A
> >  11   A
> >
> > I want to locate the rows where x >=10 and y="A". I know how to do it to
> > vectors by using
> > which, but how to do it with the dataframe?
> >
> > Thank you very much!
> >
> >
> > Zhihua Li
> >
> > _________________________________________________________________
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> >
>

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