CreateHousingFaceBlocks.R

library(tidyverse)
library(sf)

# This script:
#   1) retrieves the parcel polygons
#   2) filters for residential parcels (C_A_CLASS == 1)
#   3) creates a face-block variable, e.g. the block "100 N 1ST ST"
#   4) summaries the parcel polygons to larger face-block polygons,
#       made up of just the residential polygons on each block

# This might take a few minutes to download
parcels <- st_read("https://milwaukeemaps.milwaukee.gov/arcgis/rest/services/property/parcels_mprop/MapServer/2/query?returnGeometry=true&where=1=1&outFields=*&f=geojson")

# TAXKEYS identified by BLDG_TYPE code
resi.taxkeys <- read_csv("data/ParcelsWithBuildingTypes.csv")

# Add face block id to each parcel polygon
parcels.with.blocks <- parcels %>%
  # construct face-block variable
  mutate(block_number = paste0(str_sub(HOUSE_NR_LO, 1, -3), "00"),
         face_block = paste(block_number, SDIR, STREET),
         face_block = ifelse(!is.na(STTYPE), paste(face_block, STTYPE), face_block))

# Create face block polygons consisting of only housing parcels
resi.blocks <- parcels.with.blocks %>%
  filter(TAXKEY %in% resi.taxkeys$TAXKEY) %>% # just parcels with housing
  group_by(face_block) %>%
  summarise()

# Create face block polygons consisting of ALL parcels
all.blocks <- parcels.with.blocks %>%
  group_by(face_block) %>%
  summarise()


st_write(resi.blocks, "housing_face_blocks/housing_face_blocks.shp", delete_dsn = T)
st_write(all.blocks, "housing_face_blocks/all_face_blocks.geojson")