https://github.com/oliverhennhoefer/r-focal-getis-ord

Robust Getis-Ord G and G* statistic devised by Julian Bruns (2018). Reduces spatial scale effects by modifying the global parameter.
https://github.com/oliverhennhoefer/r-focal-getis-ord

anomaly-detection bivand bruns extension focal getis getis-ord getis-ord-g hotspot ord package r regional roger spatial-analysis spdep

Last synced: about 2 months ago
JSON representation

Robust Getis-Ord G and G* statistic devised by Julian Bruns (2018). Reduces spatial scale effects by modifying the global parameter.

• Host: GitHub
• URL: https://github.com/oliverhennhoefer/r-focal-getis-ord
• Owner: OliverHennhoefer
• Created: 2020-06-12T08:50:17.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2020-09-27T16:20:19.000Z (over 4 years ago)
• Last Synced: 2024-01-27T05:11:40.176Z (11 months ago)
• Topics: anomaly-detection, bivand, bruns, extension, focal, getis, getis-ord, getis-ord-g, hotspot, ord, package, r, regional, roger, spatial-analysis, spdep
• Language: R
• Size: 34.2 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

README

        
# Focal Getis-Ord

Robust Getis-Ord G and G* statistic devised by Julian Bruns (2018)12. The modified function reduces spatial scale effects by replacing the global parameter with a focal (regional) parameter. The method is implemented to extend the _spdep_-package by Roger Bivand

:round_pushpin: disy Informationssysteme GmbH. https://www.disy.net/de/ 


## Dependencies:


:wrench: __spdep__-package, for neighborhood definition and weighting schemes


## Parameters:


As for spdep::localG(), additionally:

- Input: _weighted neighborhood list_ ("listw" "nb"), defining the _focal_3 parameter __listw_f__


- Output: _localG_, list containing the geographically weighted z-scores of Focal Getis-Ord G* - can be converted to a vectors ton then be attached to a spatial class (package: __sp__)


The function is written in the same manner as __spdep::localG__, implementing the original Getis-Ord G* and can be applied in thevery same way. Additionally, the parameter __listw_f__ has to be defined (spdep::poly2nb and spdep::nb2listw).


The area defined by the focal parameter should be smaller then the analysed area of study (global). For focal areas that include the analysed area of study as a whole, the obtained results become equal to the original Getis-Ord G*.



Exemplary visualization (ggplot2) of the resulting z-scores for focalG():




  





1 https://publikationen.bibliothek.kit.edu/1000083353


2 https://publikationen.bibliothek.kit.edu/1000071483


3 Focal Getis-Ord G* replaces the _global mean_ of the original Getis-Ord G* with a _focal mean_ that changes for every iteration, representing the _focal_ neighborhood to that the current spatial analysis unit is compared to (in order to obtain statistical z-scores).