[R] to remove duplicate values

[Charles C. Berry]

On Mon, 5 Jul 2010, Moohwan Kim wrote:

> Dear R family,
>
> Suppose I have two series.
>
> order value
> 1  0.52
> 2  0.23
> 3  0.43
> 4  0.21
> 5  0.32
> 6  0.32
> 7  0.32
> 8  0.32
> 9  0.32
> 10 0.12
> 11 0.46
> 12 0.09
> 13 0.32
> 14 0.25
>
> For these two series, I figured out the way to detect the locations of
> duplicate values.

You _asked how_ to do it on R-help and got several answers showing how to 
do it.

That doesn't count as 'figured out how to do it'. You should give credit 
where it is warranted.


> The next thing to do is remove the repeated values except for a value
> that would not be next to each other.

Well, that is what you should have asked in the first place.

The answer is actually simpler and need not involve duplicated().

Use one each of these operations

 	head
 	tail
 	!=
 	c
 	[

in that order and you have a neat one-liner that returns the original 
data.frame without the adjacent duplicates.

And since I did not say exactly how to do it, you will be able to claim 
that you "figured out the way" albeit with assistance. ;-)


> In other words, while keeping the 13th value, I want to remove
> observations from 6th to 9th.
> That is my end goal.
>
> Could you help me reach the goal?
>
> best
> moohwan
>
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>

Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901