[R] Selecting closest values

[jim holtman]

If we assume the distance is linear, this might work:

> x
   ID loc
1   1 144
2   2 144
3   3 140
4   4 126
5   5 120
6   6 112
7   7 100
8   8  99
9   9  91
10 11  90
11 12  90
12 13  89
13 15  86
14 16  85
15 17  85
16 18  80
17 19  79
18 20  79
19 21  78
20 22  78
21 23  76
22 24  74
23 25  73
24 26  72
25 27  71
26 28  68
27 29  68
28 30  68
> x.outer <- outer(x$loc, x$loc, function(a,b) abs(a - b))
> # set diag to Inf so a point is not closest to itself
> diag(x.outer) <- Inf
> # assume that you choose the 8th element, here are the closest IDs
> x$ID[order(x.outer[,8])]
 [1]  7  9 11 12 13  6 15 16 17 18 19 20  5 21 22 23 24 25  4 26 27 28
29 30  3  1  2  8
>
>



On Sun, Mar 22, 2009 at 2:04 PM, P_M <pmartinu at broadpark.no> wrote:
>
> Yes, of course.
>
> ID      loc
> 1       144
> 2       144
> 3       140
> 4       126
> 5       120
> 6       112
> 7       100
> 8       99
> 9       91
> 11      90
> 12      90
> 13      89
> 15      86
> 16      85
> 17      85
> 18      80
> 19      79
> 20      79
> 21      78
> 22      78
> 23      76
> 24      74
> 25      73
> 26      72
> 27      71
> 28      68
> 29      68
> 30      68
> .       .
> .       .
> 185     -22
>
>
> P_M wrote:
>>
>> Hi
>> I have a table with ID (1 to 183) and Location (144 to -22).
>> My problem is that I want to select the 10 ID's that are closest in
>> Location to ID 1, ID 2 and so on.
>> Also, some ID have the same Location. Say, if 11 ID's are closest to ID
>> 100 I want to randomly choose one of the ID's to select 10 ID's total.
>>
>> Thank you
>>
>>
>>
>>
>
> --
> View this message in context: http://www.nabble.com/Selecting-closest-values-tp22647126p22648754.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at 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.
>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?