FSAs in Vancouver CMA

fsa_cma.R

# Get v0.5.6 of cancensus for FSA geography
# remotes::install_github("mountainMath/cancensus", ref = "v0.5.6")
library(cancensus)
library(tongfen)
library(dplyr)
library(sf)
library(ggplot2)

dataset <- "CA21"

# Get Vancouver CMA

cma <- get_census(dataset,
  regions = list(PR = 59), # BC province code
  level = "CMA",
  geo_format = "sf"
) %>%
  filter(name == "Vancouver (B)") %>%
  select(name, geometry)

# Get FSA geographies
fsa <- get_statcan_geographies(2021, "FSA") %>%
  filter(PRUID == 59) %>%
  select(fsa = CFSAUID, geometry)

# Reproject FSAs to match projection of CMA
st_crs(cma)

fsa <- fsa %>%
  st_transform(crs = 4326)

# Get overlap of FSAs with CMA

fsa_cma_overlap <- tongfen_tag_largest_overlap(source = fsa, target = cma, target_id = "name")

# ...overlap_fraction field shows prop of overlap, usually it's pretty clear what's a genuine overlap:
hist(fsa_cma_overlap[["...overlap_fraction"]])

# Take > 0.8 as overlap
fsa_in_vancouver_cma <- fsa_cma_overlap %>%
  filter(...overlap_fraction > 0.8)

ggplot() + 
  geom_sf(data = fsa_in_vancouver_cma, fill = "blue", colour = "blue", alpha = 0.25) + 
  geom_sf(data = cma, fill = NA, colour = "black")

# Bowen Island is missed here, part of V0N which is huge (includes more northern, island, etc) - but probably won't be part of our analysis anyways