R help - Sep 2012 - unique with tolerance

Dear R Users and Developers,

I am trying to do the equivalent of

v <- c(1,2,3,3,2,1,)
vu <- unique(v)

for a vector such as

v2 <- c(1.02, 2.03, 1.00, 3.04, 3.06)
vut <- ...

As indicated in the subject, we need approximately unique values with a defined
tolerance, i.e. for the v2 vector the resulting vut vector using a tolerance of
.1 should return e.g.

[1] 1.02 2.03 3.06

Also, mean/min values instead of max could be returned.

My actual question: Is there a convenience function or other mechanism already
implemented that could do something similar?

Thanks in advance,
Michael

On 06/09/2012 6:48 AM, Michael Bach wrote:
> Dear R Users and Developers,
>
> I am trying to do the equivalent of
>
> v <- c(1,2,3,3,2,1,)
> vu <- unique(v)
>
> for a vector such as
>
> v2 <- c(1.02, 2.03, 1.00, 3.04, 3.06)
> vut <- ...
>
> As indicated in the subject, we need approximately unique values with a
defined
> tolerance, i.e. for the v2 vector the resulting vut vector using a
tolerance of
> .1 should return e.g.
>
> [1] 1.02 2.03 3.06
>
> Also, mean/min values instead of max could be returned.
>
> My actual question: Is there a convenience function or other mechanism
already
> implemented that could do something similar?
It might be enough to round your values before checking.  For the example,

dups <- duplicated( round(v2) )
v2[!dups]

(This gives 3.04 rather than 3.06; I don't know if you care.)

Duncan Murdoch

Hi
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Michael Bach
> Sent: Thursday, September 06, 2012 12:48 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] unique with tolerance
> 
> Dear R Users and Developers,
> 
> I am trying to do the equivalent of
> 
> v <- c(1,2,3,3,2,1,)
> vu <- unique(v)
> 
> for a vector such as
> 
> v2 <- c(1.02, 2.03, 1.00, 3.04, 3.06)
> vut <- ...
> 
> As indicated in the subject, we need approximately unique values with a
> defined tolerance, i.e. for the v2 vector the resulting vut vector
> using a tolerance of
> .1 should return e.g.
> 
> [1] 1.02 2.03 3.06
> 
> Also, mean/min values instead of max could be returned.
> 
> My actual question: Is there a convenience function or other mechanism
> already implemented that could do something similar?
Not exact values as requested but

unique(round(v2))

Regards
Petr
> 
> Thanks in advance,
> Michael
> 
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> and provide commented, minimal, self-contained, reproducible code.

Thanks to both of you for suggestions.

I settled for the round() approach.

much obliged,
Michael Bach