[R-sig-Geo] problems with dnearneigh of spdep
Roger Bivand
Roger.Bivand at nhh.no
Fri Oct 29 19:47:47 CEST 2004
On Fri, 29 Oct 2004, Stephane DRAY wrote:
> My version :
>
> > version
> _
> platform i386-pc-mingw32
> arch i386
> os mingw32
> system i386, mingw32
> status
> major 1
> minor 9.1
> year 2004
> month 06
> day 21
> language R
> > spdep()
> [1] "spdep, version 0.2-18, 2004-05-25"
> > sum(card(mydnn))
> [1] 9896
> > all(sapply(mydnn, length) == 99)
> [1] FALSE
I can replicate on Windows, R 1.9.1, spdep 0.2-18. I'll report back on R
2.0.0, spdep 0.2-22 in a little while.
Roger
>
> It is not the last one, I will try to update later. I think that the
> problem is in the calculation of neighbors. Perhaps, the fortran code has
> changed. I do not have the sources, so I could not verify.
>
> Thanks !
>
>
>
> At 13:01 29/10/2004, Roger Bivand wrote:
> >On Fri, 29 Oct 2004, Stephane DRAY wrote:
> >
> > > Hello,
> > > I have some strange results with the dnearneigh function.
> > > I would like to have all points of grid linked. I do something like that:
> > >
> > > > xy=expand.grid(1:10,1:10)
> > > > mydnn=dnearneigh(as.matrix(xy),d1=0,d2=50)
> > > > mydnn
> > > Neighbour list object:
> > > Number of regions: 100
> > > Number of nonzero links: 9896
> > > Percentage nonzero weights: 98.96
> > > Average number of links: 98.96
> > > I assume to have 100*100-100=9900 links.
> > >
> > > > m01=nb2mat(mydnn,style="B")
> > > > apply(m01,1,sum)
> > > 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
> > > 19 20 21 22 23 24 25 26 27
> > > 98 99 99 99 99 99 99 99 99 98 99 99 99 99 99 99 99 99
> > > 99 99 99 99 99 99 99 99 99
> > > 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
> > > 46 47 48 49 50 51 52 53 54
> > > 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
> > > 99 99 99 99 99 99 99 99 99
> > > 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
> > > 73 74 75 76 77 78 79 80 81
> > > 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99 99
> > > 99 99 99 99 99 99 99 99 99
> > > 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98
> > 99 100
> > > 99 99 99 99 99 99 99 99 99 98 99 99 99 99 99 99 99
> > 99 98
> > >
> > > It seems that the first and the last points are not linked. I have
> > choose a
> > > value of d2 very high, and the distance between this two points is only
> > > sqrt(162)
> >
> >I can't replicate this:
> >
> > > version
> > _
> >platform i686-pc-linux-gnu
> >arch i686
> >os linux-gnu
> >system i686, linux-gnu
> >status
> >major 2
> >minor 0.0
> >year 2004
> >month 10
> >day 04
> >language R
> > > library(spdep)
> > > spdep()
> >[1] "spdep, version 0.2-22, 2004-08-07"
> > > xy=expand.grid(1:10,1:10)
> > > mydnn=dnearneigh(as.matrix(xy),d1=0,d2=50)
> > > mydnn
> >Neighbour list object:
> >Number of regions: 100
> >Number of nonzero links: 9900
> >Percentage nonzero weights: 99
> >Average number of links: 99
> >
> >The line "Number of nonzero links:" is calculated as:
> >
> > > sum(card(mydnn))
> >[1] 9900
> >
> >You can also look at:
> >
> > > all(sapply(mydnn, length) == 99)
> >[1] TRUE
> > > which(sapply(mydnn, length) != 99)
> >numeric(0)
> >
> >if you want to be sure it isn't card() getting it wrong. Puzzling. I don't
> >think any of the relevant code has changed since September 2003.
> >
> >Roger
> >
> > >
> > > Any ideas ?
> > > Thanks
> > > Stéphane DRAY
> > >
> > --------------------------------------------------------------------------------------------------
> >
> > >
> > > Département des Sciences Biologiques
> > > Université de Montréal, C.P. 6128, succursale centre-ville
> > > Montréal, Québec H3C 3J7, Canada
> > >
> > > Tel : (514) 343-6111 poste 1233 Fax : (514) 343-2293
> > > E-mail : stephane.dray at umontreal.ca
> > >
> > --------------------------------------------------------------------------------------------------
> >
> > >
> > >
> > Web http://www.steph280.freesurf.fr/
> > >
> > > _______________________________________________
> > > R-sig-Geo mailing list
> > > R-sig-Geo at stat.math.ethz.ch
> > > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> > >
> >
> >--
> >Roger Bivand
> >Economic Geography Section, Department of Economics, Norwegian School of
> >Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
> >Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
> >e-mail: Roger.Bivand at nhh.no
> >
> >_______________________________________________
> >R-sig-Geo mailing list
> >R-sig-Geo at stat.math.ethz.ch
> >https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
> Stéphane DRAY
> --------------------------------------------------------------------------------------------------
>
> Département des Sciences Biologiques
> Université de Montréal, C.P. 6128, succursale centre-ville
> Montréal, Québec H3C 3J7, Canada
>
> Tel : (514) 343-6111 poste 1233 Fax : (514) 343-2293
> E-mail : stephane.dray at umontreal.ca
> --------------------------------------------------------------------------------------------------
>
> Web http://www.steph280.freesurf.fr/
> --------------------------------------------------------------------------------------------------
>
>
>
--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no
More information about the R-sig-Geo
mailing list