# [R] Split a vector(list) into 3 list

Fri May 18 04:14:00 CEST 2007

```Don't need to upgrade R just to get index() working. You can try the
following modification.

v <- sample(1:3, 30, replace = TRUE)
split( 1:length(v), v )

Should do the trick. Check out the reverse function unsplit().

Leeds, Mark (IED) wrote:
> index is definitely defined in my version ( 2.4.0) because when I do
> ?index, I get info. Maybe you
> Are using an older or younger version of R ? I'm really not sure why you
> are experiencing that problem.
>
>
> -----Original Message-----
> From: Patrick Wang [mailto:pwang at berkeley.edu]
> Sent: Thursday, May 17, 2007 8:44 PM
> To: Leeds, Mark (IED)
> Cc: Patrick Wang; r-help at stat.math.ethz.ch
> Subject: RE: [R] Split a vector(list) into 3 list
>
> Thanks,
>
> no index function was defined in R.
>
> I try to use the split(order(temp), temp), the number of groups are
> correct, however the result doesnot seem to be correct. I try to match
> before the ordered index and the original index.
>
> Pat
>
>> If  temp is your vector then split(index(temp),temp) will give you
>> what you want.
>>
>>
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch
>> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Patrick Wang
>> Sent: Thursday, May 17, 2007 8:15 PM
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] Split a vector(list) into 3 list
>>
>> Hi,
>>
>> I have a vector contains values 1,2,3.
>>
>> Can I call a function split to split it into 3 vectors with 1
>> corresponds to value ==1, which contain all the indexes for value==1.
>>
>> 2 corresponds to value ==2 which contain all the indexes for value=2
>>
>> Thanks
>> pat
>>
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