local R2
On Mon, 7 Dec 2009, Eda Laze wrote:
Hello, Thank you very much Roger for your helpful answer. It worked pretty well. When I run gwr with polygon data I get: "Warning message: In gwr(formula = AFCCH07HA ~ ALDRO12MEA + ALDRO1MEAN + ALHSETTMEA + : data is Spatial* object, ignoring coords argument" However, I may provide now two results in one of combinations of variables I use. I use the same number of neighbors and variables in both cases, the only change is as follows: In case one I use longlat =TRUE and in case two I do not write longlat=TRUE. case one (longlat=TRUE): local R2 values vary from 0.1651 to 0.5328 ? ? gwr.e ? ? ? ? ? ? ? ?pred ? ? ? ? ? ? ? ? ? ?localR2 ?Min. ? :-465.4243 ? Min. ? :-142.267 ? Min. ? :0.1651 ?1st Qu.: -17.4693 ? 1st Qu.: ? 5.429 ? 1st Qu.:0.2461 ?Median : ?-3.2120 ? Median : ?16.735 ? Median :0.2788 ?Mean ? : ? 0.3215 ? Mean ? : ?17.798 ? Mean ? :0.2835 ?3rd Qu.: ?16.0616 ? 3rd Qu.: ?29.726 ? 3rd Qu.:0.3181 ?Max. ? : 321.4507 ? Max. ? : 162.569 ? Max. ? :0.5328 ?sum.w ?Min. ? :33.40 ?1st Qu.:56.47 ?Median :62.22 ?Mean ? :62.32 ?Max. ? :91.10 case two (without longlat=TRUE): local R2 values vary from 0.06066 to 0.70522 ? ? gwr.e ? ? ? ? ? ? ? ?pred ? ? ? ? ? ? localR2 ?Min. ? :-323.5487 ? Min. ? :-244.457 ? Min. ? :0.06066 ?1st Qu.: -13.4717 ? 1st Qu.: ?-1.223 ? 1st Qu.:0.32168 ?Median : ?-1.2330 ? Median : ?14.144 ? Median :0.38511 ?Mean ? : ? 0.9375 ? Mean ? : ?17.181 ? Mean ? :0.40192 ?3rd Qu.: ? 9.5695 ? 3rd Qu.: ?38.060 ? 3rd Qu.:0.47538 ?Max. ? : 320.2477 ? Max. ? : 176.522 ? Max. ? :0.70522 ? ? ? ? ?sum.w ?Min. ? : 36.83 ?1st Qu.: 50.90 ?Median : 56.49 ?Mean ? : 57.56 ?3rd Qu.: 62.76 ?Max. ? :120.35 I thought that adapt=0.01 (number of neighbors) could decide on weights. Visualisation of map differs, map two is rather a "surface". Does it mean that weights differ from case one to two due to the fact that "longlat = TRUE uses distances on the ellipse with WGS84 parameters" as described in the spgwr manual updated in June 2009. The polygon data are projected in: Projected Coordinate System: ? ?WGS_1984_UTM_Zone_34N. I would welcome very much an accurate response, despite my efforts to get the answer these days by myself.
Since the data are projected, they are in UTM zone 34, use longlat=FALSE.
As a sanity check, assign the projection to the object:
proj4string(obj) <- CRS("+proj=utm +zone=34 +datum=WGS84")
then inverse project to longlat:
library(rgdal)
obj_ll <- spTransform(obj, CRS("+proj=longlat +datum=WGS84"))
and rerun the analysis with longlat=TRUE (the bandwidth will be in km not
m), and even do:
writeOGR(obj_ll, "obj.kml", "obj", driver="KML")
for the input object, displaying in Google Earth or similar.
Roger
Thank you in advance ++++++++++++ On Fri, Nov 27, 2009 at 1:12 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
On Fri, 27 Nov 2009, Eda Laze wrote:
Hello, I am currectly using gwr in R to get local R2. I have a shape file - polygon data. When I write codes as below: case 1 and 2, I get two different Local R2 values and maps: case1.adpt<-gwr(FCHA~PAC1+PAC2+PAC6, data=filename, coords=cbind(filename$X, filename$Y), adapt= 0.01, longlat=TRUE). case2.adpt<-gwr(FCHA~PAC1+PAC2+PAC6, data=filename, coords=cbind(filename$X, filename$Y), adapt= 0.01, hatmatrix = TRUE, se.fit=TRUE). Local R2 have different values from case 1 and map is different as well.
In the second case, you are not using longlat=TRUE, which will give rather different weights. Please only give examples with available data sets, and include say the first 5 local R2 values, so that helpers know that they are looking at the same thing as you are. Always state the output of sessionInfo(). Hope this helps, Roger
Furthermore, when I visualize case 1: i.e., local R2 on map, each polygon has a certain value and responding color while in case 2: map shows clustering of Local R2 (values) similar to Georgia case study. However, I wonder why this happen and which is the right way to get local R2. I read spgwr manual and update. Though an accurate answer is very welcome. Thank you.
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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 at nhh.no
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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 at nhh.no