Hi,
Is "adapt=TRUE"(spgwr) not the same as "adaptive Spatial Kernel"(SAM)?The
result of "adaptive Spatial Kernel" may be better than fixed bandwidth. If I
want to ues "adaptive Spatial Kernel" in spgwr, how to write the code?
Thanks a lot.
Cheers.
> Hi,
> I think that I use the same bandwidth and kernel. In SAM, I use "spatial
> Weighting Function"=gaussian, adaptive Spatial Kernel, and compute
> Geographical Distances based on longitudinal coordinate(X) and latitudinal
> coordinate(Y). In spgwr, gweight is gwr.Gauss and adapt is TRUE.
>
> For example, this is my code:
> PET.bw <- gwr.sel(SPECIES_RI ~ PET, data=variables,
> coords=cbind(variables$LONGX, variables$LATY),adapt=TRUE)
> PET.gauss <- gwr(SPECIES_RI ~ PET, data=variables,
> coords=cbind(variables$LONGX, variables$LATY), bandwidth=PET.bw,
> gweight=gwr.Gauss,adapt=TRUE,hatmatrix=TRUE)
So where do you pass PET.bw to the gwr() function? adapt=TRUE will treat
the adaptive proportion as 1, so include all data points. If you want to
compare, use a fixed bandwidth in both, with no CV selection. Then you
compare like with like.
Note that your messages are *not* reaching the list, they must be sent to:
r-sig-geo@stat.math.ethz.ch, not
r-sig-geo-requ...@stat.math.ethz.ch
You are not thinking carefully and are rushing into things and drawing
wrong conclusions.
>
> Thanks a lot.
>
> Cheers.
>
>
>
> ÔÚ2010-05-12 20:28:47£¬"Roger Bivand" <roger.biv...@nhh.no> дµÀ£º
>> On Wed, 12 May 2010, huangykiz wrote:
>>
>>> Hi,
>>> One of SAM author ("Jos¨¦ Alexandre Felizola Diniz
>>> Filho"<di...@icb.ufg.br>) say that they also base on GWR3 (the Fotherigham
>>> book) and the data used within each kernel
>>> may be some slight differences
>>
>> Naturally, if you are not using exactly the same kernel and bandwidth, you
>> should not be surprised by differences in values. Please make sure that
>> the bandwidth and kernel are the same and try again.
>>
>> Roger
>>
>>> Cheers
ÔÚ2010-05-12 20:28:47£¬"Roger Bivand" <roger.biv...@nhh.no> дµÀ£º
>On Wed, 12 May 2010, huangykiz wrote:
>
>> Hi,
>> One of SAM author ("Jos¨¦ Alexandre Felizola Diniz Filho"<di...@icb.ufg.br>)
>> say that they also base on GWR3 (the Fotherigham book) and the data used
>> within each kernel
>> may be some slight differences
>
>Naturally, if you are not using exactly the same kernel and bandwidth, you
>should not be surprised by differences in values. Please make sure that
>the bandwidth and kernel are the same and try again.
>
>Roger
>
>> Cheers.
>>
ÔÚ2010-05-12 15:27:58£¬"Roger Bivand" <roger.biv...@nhh.no> дµÀ£º
>On Wed, 12 May 2010, huangykiz wrote:
>
>> Hi,
>>
>> I am sorry I donot know how to install module spgwr from sourceforge (I can
>> find it on the web
>> http://r-spatial.cvs.sourceforge.net/viewvc/r-spatial/spgwr/R/gwr.R?view=log).
>> So I use the code sketch to calculate quasi-global R2. The results are
>> different between SAM and spgwr(Attached are the results ). The quasi-global
>> R2 in R is 0.4515894, but in SAM is 0.696.
>> This is my code:
>>
>> library(spgwr)
>> Environmental_variables<-read.csv("Environmental_variables100.csv",header=TRUE)
>> attach(Environmental_variables)
>> region_PET.bw <- gwr.sel(SPECIES_RI ~ PET, data=Environmental_variables,
>> coords=cbind(Environmental_variables$LONGX,
>> Environmental_variables$LATY),adapt=TRUE)
>> region_PET.gauss <- gwr(SPECIES_RI ~ PET, data=Environmental_variables,
>> coords=cbind(Environmental_variables$LONGX, Environmental_variables$LATY),
>> bandwidth=region_PET.bw, gweight=gwr.Gauss,adapt=TRUE,hatmatrix=TRUE)
>> names(region_PET.gauss$SDF)
>> region_PET.gauss$SDF$localR2
>> 1 -
>> (region_PET.gauss$results$rss/crossprod(scale(Environmental_variables$SPECIES_RI,
>> scale=FALSE)))
>>
>> Thank you very much.
>
>SAM is closed source - ask them how they compute it. For spgwr, the code
>is provided, so you can read it for yourself. For the record, the current
>gwr() code in spgwr gives the same value as GWR3, which is also closed
>source, and where the Effective number of parameters (model: traceS),
>Sigma, and Residual sum of squares also agree. I suppose SAM has a
>different understanding of GWR internals than the authors of the GWR book.
>
>Once again:
>
>Please *do* write to the R-sig-geo list rather than to me directly -
>others can answer your question as well, perhaps better, and in a more
>timely way than I can. In addition, threads in the list can be searched in
>the archives, so others can avoid the same problem later.
>
>Please summarise to the list if this resolves the problem.
>
>Roger
>
>>
>>
>>
>>
>>
>> ÔÚ2010-05-12 01:16:18£¬"Roger Bivand" <roger.biv...@nhh.no> дµÀ£º
>>> On Wed, 12 May 2010, huangykiz wrote:
>>>
>>>> Hi, I just need one for global, not *each* fit point. In this case, how
>>>> can I select or do? Why in other software such as SAM(Spatial Analysis
>>>> in Macroecology) just gives one R2?
>>>
>>> If you believe theirs, good luck! The authors of the GWR book have local
>>> R^2 values in GWR3 and formulae that are wrong by their own admission in
>>> private emails. The localR2 now agrees with the as-yet unreleased GWR4
>>> from the GWR authors. How SAM can be "better", I don't know. What you are
>>> suggesting is that the model fitted with fit points at data points (but
>>> not at other fit points) might have a "quasi-global" R^2, based on the RSS
>>> of the pooled fit. For the columbus case, that might be:
>>>
>>> 1 - (col.gauss$results$rss/crossprod(scale(columbus$crime, scale=FALSE)))
>>>
>>> but I don't know whether this is in any way correct. I've added it as:
>>>
>>> Quasi-global R2:
>>>
>>> to the print output of a GWR model fitted with a hatmatrix, and have
>>> committed it to sourceforge, project r-spatial, module spgwr. Arguably, it
>>> ought to be adjusted by the ratio of degrees of freedom, but I don't trust
>>> the DF either. Could you please check out spgwr from sourceforge ,install
>>> it from source, and confirm that the "quasi-global R2" does the same as
>>> SAM, or use the code sketch above to do the same, and report back?
>>>
>>> Roger
>>>
>>>>
>>>> Thanks a lot.
>>>>
>>>> Cheers,
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ÔÚ2010-05-11 23:59:44£¬"Roger Bivand" <roger.biv...@nhh.no> дµÀ£º
>>>>> On Tue, 11 May 2010, huangykiz wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> There are 49 localR2 in the results. Which one do I need? The code
>>>>>> "look for localR2:" cannot run.
>>>>>
>>>>> Well, how many do you want? There is one for each fit point, they are
>>>>> *local* R2. Please do try to grasp what GWR does - it fits one moddel for
>>>>> *each* fit point.
>>>>>
>>>>>>
>>>>>> Thans a lot
>>>>>>
>>>>>> Cheers.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ÔÚ2010-05-11 22:33:59£¬"Roger Bivand" <roger.biv...@nhh.no> дµÀ£º
>>>>>>> On Tue, 11 May 2010, huangykiz wrote:
>>>>>>>
>>>>>>>> Hi, OK. But I need it for compariation. In what some contexts to get
>>>>>>>> it?
>>>>>>>> May you tell me how to get it?
>>>>>>>
>>>>>>> library(spgwr)
>>>>>>> data(columbus)
>>>>>>> col.bw <- gwr.sel(crime ~ income + housing, data=columbus,
>>>>>>> coords=cbind(columbus$x, columbus$y))
>>>>>>> col.gauss <- gwr(crime ~ income + housing, data=columbus,
>>>>>>> coords=cbind(columbus$x, columbus$y), bandwidth=col.bw, hatmatrix=TRUE)
>>>>>>> names(col.gauss$SDF)
>>>>>>>
>>>>>>> look for localR2:
>>>>>>>
>>>>>>> col.gauss$SDF$localR2
>>>>>>>
>>>>>>> But do not rely on it or use it for anything at all! Like all GWR, it
>>>>>>> is
>>>>>>> most unreliable!
>>>>>>>
>>>>>>> Roger Bivand
>>>>>>>
>>>>>>>>
>>>>>>>> Thank you very much for your great helps
>>>>>>>>
>>>>>>>> Best regards.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> ÔÚ2010-05-11 18:28:44£¬"Roger Bivand" <roger.biv...@nhh.no> дµÀ£º
>>>>>>>>> On Tue, 11 May 2010, huangykiz wrote:
>>>>>>>>>
>>>>>>>>>> Dear professor Bivand,
>>>>>>>>>>
>>>>>>>>>> I am a strudent. I recently use GWR(Geographically
>>>>>>>>>> weighted regression) model. May I ask you a question? There is not
>>>>>>>>>> Coefficient of Determination in the results of GWR. How can I get
>>>>>>>>>> it?
>>>>>>>>>> What is the programs to get it?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Please address questions like this to the R-sig-geo list rather than
>>>>>>>>> to me
>>>>>>>>> directly in future.
>>>>>>>>>
>>>>>>>>> The local R2 values are available in some contexts when running
>>>>>>>>> gwr(), but
>>>>>>>>> are not well defined (neither in the GWR book nor in
>>>>>>>>> implementations). I
>>>>>>>>> advise against their use - they are most probably meaningless.
>>>>>>>>>
>>>>>>>>> Hope this helps,
>>>>>>>>>
>>>>>>>>> Roger Bivand
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Thank you very much for your any helps.
>>>>>>>>>>
>>>>>>>>>> Best regards.
>>>>>>>>>>
>>>>>>>>>> Yong Huang
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> 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.biv...@nhh.no
>>>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> 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.biv...@nhh.no
>>>>>
>>>>> --
>>>>> 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.biv...@nhh.no
>>>
>>> --
>>> 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.biv...@nhh.no
>
>--
>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.biv...@nhh.no
[[alternative HTML version deleted]]
_______________________________________________
R-sig-Geo mailing list
R-sig-Geo@stat.math.ethz.ch
https://stat.ethz.ch/mailman/listinfo/r-sig-geo
