In arc2r/book: All things R Spatial or A guide to spatial R for Recovering ArcGIS Users

Analysing Patterns Toolset

For this chapter, you will need the following R Packages:

library(arc2r)
library(sf)
library(ggplot2)

Spatial Autocorrelation (Global Morans I)

Here's the function to calculate Morans I

morans_i <- function(sf_object,col) {
  require(sf)
  n <- nrow(sf_object)
  y <- unlist(st_set_geometry(sf_object,NULL)[,col],use.names = FALSE)
  ybar <- mean(y, na.rm = TRUE)
  dy <- y - ybar
  dy_sum <- sum(dy^2, na.rm = TRUE)
  vr <- n/dy_sum
  w <- st_touches(sf_object,sparse = FALSE)
  pm <- tcrossprod(dy)
  pmw <- pm * w
  spmw <- sum(pmw, na.rm = TRUE)
  smw <- sum(w, na.rm = TRUE)
  sw  <- spmw / smw
  MI <- vr * sw
  MI
}

data("zweitwohnung_gemeinden")

zweitwohung <- st_set_crs(zweitwohnung_gemeinden,2056)

zweit_plot <- ggplot(zweitwohung) +
  geom_sf(aes(fill = ja_in_percent), colour = NA) +
  scale_fill_gradient2(low = "#2c7bb6",mid = "#ffffbf",high = "#d7191c", midpoint = 50,breaks = c(0,25,50,75,100),limits = c(0,100))+
  labs(title = "Results from the 'Zweitwohungsinitiative'",
       subtitle = "Percent in Approval",
       fill = "") +
  theme_void() +
  theme(legend.position = "bottom")

zweit_plot

morans_i(zweitwohung,"ja_in_percent")

arc2r/book documentation built on March 5, 2021, 2:10 p.m.