Create dummy variable for all neighborhood region depending on another dummy variable (sf object)

Question

I have a spatial dataframe (sf) of all European NUTS2 regions. Within this sf object certain regions have a dummy = 1, and others a dummy = 0.

How can I create a new dummy (lets say "dummy_neighbor") where all the neighboring (st_touches?) regions of the regions with dummy==1 get a dummy_neighbor==1, and all those not touching a dummy==1 region get a dummy_neighbor==0?

Answer 1

For the time being I have this work-around. But I guess there musst be an easier solution?

# load packages
library(sf)
library(here)
library(tidyverse)
library(spdep)
library(expp)

# import nuts 2 sf object
nuts2_sf <- st_read(here("Data", "nuts2_data", "final_nuts.shp"))
# take row numbers as extra column for later
nuts2_sf$rownumber = 1:nrow(nuts2_sf)

#neighbouring list
neighbour <- poly2nb(nuts2_sf, row.names="NUTS_ID", queen=TRUE)
# transform nb into data frame
nb_df <- plyr::ldply(neighbour, rbind)
nb_df$rownumber = 1:nrow(nb_df) # get rownbumer as column

# merge neighbour-list-df with sf by rownumber
df <- merge(nuts2_sf, nb_df, by = "rownumber")

# extract all neighbours of tp100_d=1 
# (tp100_d is the name of the original dummy variable)
df_dummy <- df %>% filter(tp100_d == 1)
df_dummy$geometry  <- NULL
all_neighbours <- as.vector(as.matrix(df_dummy[,c(66:76)])) %>% unique(.)

# create new neighbourhood-dummy for all neighbours (but not if its a neighbour that has a 1 in its original dummy)
nuts2_sf <- nuts2_sf %>% mutate(nb_dummy = ifelse(rownumber %in% all_neighbours & tp100_d == 0, 1, 0))