Check

?"=="

and try

f[f == 4]

More in section 2.4 at http://cran.r-project.org/doc/manuals/R-intro.pdf


On Wed, May 8, 2013 at 5:14 PM, jpm miao <miaojpm@gmail.com> wrote:

> Thanks, but why does  f[f=4] yield 16 instead of 4?
>
> > f
> [1]   -2    4   -8   16  -32   64 -128
> > f[f<0]
> [1]   -2   -8  -32 -128
> > f[f>0]
> [1]  4 16 64
> > f[f=4]
> [1] 16
>
>
> 2013/5/8 Jorge I Velez <jorgeivanvelez@gmail.com>
>
>> f [ f < 0 ]
>>
>>
>> On Wed, May 8, 2013 at 11:54 AM, jpm miao <miaojpm@gmail.com> wrote:
>>
>>> Hi,
>>>
>>>    I have a vector f with some negative columns. I remember that there is
>>> an easy expression that can find out negative items. Can someone tell me
>>> how I can do it?
>>>
>>>    It seems to be
>>>    f[i such that f[i]<0 ...]
>>>
>>>    Thanks,
>>>
>>> Miao
>>>
>>> > d<-1:7
>>> > f<-(-2)^d
>>> > f
>>> [1]   -2    4   -8   16  -32   64 -128
>>>
>>>         [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help@r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>
>

	[[alternative HTML version deleted]]

