In-class_Ex05

Importing Data

pacman::p_load(tidyverse, sf, sfdep, tmap)

studyArea <- st_read(dsn = "data", layer="study_area") %>% st_transform(crs = 3829)

Reading layer `study_area' from data source 
  `/Users/yashica/Desktop/xtc0/IS415-GAA/In-class_Ex/In-class_Ex05/data' 
  using driver `ESRI Shapefile'
Simple feature collection with 7 features and 7 fields
Geometry type: POLYGON
Dimension:     XY
Bounding box:  xmin: 121.4836 ymin: 25.00776 xmax: 121.592 ymax: 25.09288
Geodetic CRS:  TWD97

stores <- st_read(dsn = "data", layer="stores") %>% st_transform(crs = 3829)

Reading layer `stores' from data source 
  `/Users/yashica/Desktop/xtc0/IS415-GAA/In-class_Ex/In-class_Ex05/data' 
  using driver `ESRI Shapefile'
Simple feature collection with 1409 features and 4 fields
Geometry type: POINT
Dimension:     XY
Bounding box:  xmin: 121.4902 ymin: 25.01257 xmax: 121.5874 ymax: 25.08557
Geodetic CRS:  TWD97

Visualising the sf layers

tmap_mode("view")
tm_shape(studyArea) + 
  tm_polygons() + 
tm_shape(stores) + 
  tm_dots(col = "Name",
          size = 0.01,
          border.col = "black",
          border.lwd = 0.5) + 
  tm_view(set.zoom.limits = c(12,16))

+−

Esri.WorldGrayCanvas

OpenStreetMap

Esri.WorldTopoMap

studyArea

stores

Name

7-Eleven
Family Mart

Leaflet | Tiles © Esri — Esri, DeLorme, NAVTEQ

Local Colocation Quotients (LCLQ)

nb <- include_self(
  st_knn(st_geometry(stores), 6)
) #choose 6 and include yourself so total is 7. In the end, you'll get 3 and 4 so no even split which is good

wt <- st_kernel_weights(nb,
                        stores,
                        "gaussian",
                        adaptive = TRUE)

FamilyMart <- stores %>%
  filter(Name == "Family Mart") #select out all the stores with the name "Family Mart as dataframe
A <- FamilyMart$Name

SevenEleven <- stores %>%
  filter(Name == "7-Eleven")
B <- SevenEleven$Name

LCLQ <- local_colocation(A, B, nb, wt, 49)
#now all the parameter values you have
#A is target
#B is the neighbour i want to find if A is colocated with it

LCLQ_stores <- cbind(stores, LCLQ)
#doing a combination: LCLQ is appended over to stores. Cannot do a relational join coz these 2 layers have no unique identifier (only 1,2,3,4...)

#LHS should be store coz we want the geometry. Will always inherit the property of the first value.

tmap_mode("view")

Pls make sure to check the number of events. Should be 1409.

In in-class exercise 5, we saw the graph and now we’re learning how to deal with colocation.

Colocation quotient and pvalue - please find yourself.