gwr.bw {lctools} | R Documentation |
Optimal bandwidth estimation for Geographically Weighted Regression (GWR)
Description
This function helps choosing the optimal bandwidth for the simple Geographically Weighted Regression (GWR).
Usage
gwr.bw(formula, dframe, coords, kernel, algorithm="exhaustive",
optim.method="Nelder-Mead", b.min=NULL, b.max=NULL, step=NULL)
Arguments
formula |
the local model formula using the same syntax used in the |
dframe |
a numeric data frame of at least two suitable variables (one dependent and one independent) |
coords |
a numeric matrix or data frame of two columns giving the X,Y coordinates of the observations |
kernel |
the kernel to be used in the regression. Options are "adaptive" or "fixed". The weighting scheme used here is defined by the bi-square function |
algorithm |
a character argument that specifies whether the function will use an |
optim.method |
the optimisation method to be used. A detailed discussion is available at the 'Details' section of the function |
b.min |
the minimum bandwidth. This is important for both algorithms. In the case of the |
b.max |
the maximum bandwidth. This is important for both algorithms. In the case of the |
step |
this numeric argument is used only in the case of a |
Details
Please carefully read the optim (stats)
when using a heuristic
algorithm.
Value
bw |
The optimal bandwidth (fixed or adaptive) |
CV |
The corresponding Cross Validation score for the optimal bandwidth |
CVs |
Available only in the case of the |
Warning
Large datasets increase the processing time.
Note
Please select the optimisation algorithm carefully. To be on safe grounds use the "Brent" optim.method
with well defined b.min
and b.max
. This function needs further testing. Please report any bugs!
Author(s)
Stamatis Kalogirou <stamatis@lctools.science>
References
Fotheringham, A.S., Brunsdon, C., Charlton, M. (2000). Geographically Weighted Regression: the analysis of spatially varying relationships. John Wiley and Sons, Chichester.
Kalogirou, S. (2003) The Statistical Analysis and Modelling of Internal Migration Flows within England and Wales, PhD Thesis, School of Geography, Politics and Sociology, University of Newcastle upon Tyne, UK. https://theses.ncl.ac.uk/jspui/handle/10443/204
See Also
Examples
RDF <- random.test.data(9,9,3,"normal")
bw <- gwr.bw(dep ~ X1 + X2, RDF, cbind(RDF$X,RDF$Y), kernel = 'adaptive',
b.min = 54, b.max=55)