Robert,
Thank you, it performs exactly as desired. Until you
shared the extraction notation, I could not have conceived how
it might look, but now looks natural:
combine the thing itself 5, with neighbors of 5 and their data.
I take note of Dr. Pebesma's query as to why I would want to do
this, and it may amount to simplifying some report graphics as
against any analytical objectives. But, to be seen. I'm going to
continue working with this neighbor approach to see if it helps with
organizing data frames as I move into states and counties where
I have little or no prior knowledge of how counties are placed.
Thanks again,
Chris
Date: Thu, 24 May 2012 14:32:52 -0700
Subject: Re: [R-sig-Geo] neighborly ordering of spdf data/spacetime
From: r.hijm...@gmail.com
To: sgl...@hotmail.com
CC: r-sig-geo@r-project.org
Chris,
You can get the neighbors of a polygon from the nb object. For example, after
you do this:
nb - poly2nb(nj_cty_2.spdf)
the neighbors of polygon 5 would be
nb[[5]]
And you can extract them all (and plot them) like this
pol5andngb - nj_cty_2.spdf [ c(5, nb[[5]]), ]
Robert
On Thu, May 24, 2012 at 1:54 PM, Chris English sgl...@hotmail.com wrote:
Hello,
I am exploring some US county level housing data. I started with New Jersey
and built a SPDF and subsequently a STFDF. Data and spatial were in
alphabetical order that madematching straight forward.
The problem arises that alphabetically named spatial attributes, i.e. atlantic,
bergen (counties),are not close physically, indeed, often not neighbors.
When trying to plot a variable of interest among some neighboring counties
instead of the wholestate, hudson, bergen, essex, for example, many other
counties have to be plotted because the SPDF was created in alphabetical order.
I've spent the afternoon looking at spdep and deriving various neighbor, for
example:
nj_cty_hu_nb - poly2nb(nj_cty_2.spdf) summary(nj_cty_hu_nb)Neighbour list
object:Number of regions: 21 Number of nonzero links: 82 Percentage nonzero
weights: 18.5941 Average number of links: 3.904762 Link number distribution:
2 3 4 5 6 7 3 5 7 4 1 1 3 least connected regions:cape may hudson salem with 2
links1 most connected region:morris with 7 links
Basically I'm wondering if someone can suggest how I might go back and recreate
my spatial polygonsobject ordered by a more optimal neighbor approach and
thence construct a new spdf based upon amore neighborly order than a-z.
Thanks in advance,Chris
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