Dear Jason,
Just following the Roger´s solution, you can see the different results
using:

plot(nc.sids)
plot(nc.sids[1,], border="red", add=T)
plot(nc.sids1[1,], border="blue", add=T)

:-) Best wishes,

miltinho
brazil

On Sun, Sep 28, 2008 at 11:19 AM, Roger Bivand <Roger.Bivand@nhh.no> wrote:

> On Fri, 26 Sep 2008, Jason Gasper wrote:
>
>  I am using the readShapePoly() function in the maptools package to read in
>> shape files.  I need to order an attribute in the shapefile in ascending
>> order. For example, I have three attributes: C1,C2,C3
>>           C1         C2         C3
>> [1,] -0.5658135  0.0374106 -1.7702093
>> [2,]  0.6783104 -0.1110221 -0.7005937
>> [3,] -0.2228110  0.9176706  1.7612472
>>
>> ordered attributes based on ascending order in C2 would look like this:
>>
>>           C1         C2         C3
>> [1,]  0.6783104 -0.1110221 -0.7005937
>> [2,] -0.5658135  0.0374106 -1.7702093
>> [3,] -0.2228110  0.9176706  1.7612472
>>
>> The problem of course is that I am dealing with a shapefile and thus
>> cannot treat the attributes as a vector using the "order" function.  Has
>> anyone found a way to order attributes in a shapefile? The reason I need to
>> do this is that I have a bunch of 0's that I will need to eliminate after
>> spatial weights are created (using the poly2nb() and nb2WB() functions.  So
>> I need the index for spatial weighting and cannot simply pull out each
>> attribute and create a new sorted vector.
>>
>
> Probably using the "[" method on the SpatialPolygonsDataFrame object:
>
> library(spdep)
> example(nc.sids)
> nc.sids1 <- nc.sids[order(nc.sids$SID74),]
> nc.sids$SID74
> nc.sids1$SID74
>
> Construct the indexing variable first if need be to check what is going on.
>
> Hope this helps,
>
> Roger
>
>
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>>
>>
> --
> Roger Bivand
> Economic Geography Section, Department of Economics, Norwegian School of
> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
> e-mail: Roger.Bivand@nhh.no
>
>
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