Estimate population adjacent to MBTA stops using Census API and MBTA API.

prop_split.R

require('tidyverse')
require('tidycensus')
library('jsonlite')
require('sf')

census_api_key("<yourapikey>")

stops <- fromJSON("https://api-v3.mbta.com/stops/?filter[route]=Red", simplifyVector = TRUE)[[1]]$attributes %>%
  st_as_sf(coords =  c('longitude', 'latitude')) %>%
  st_set_crs(4326) %>%
  st_transform(2249)

pops <- get_acs(geography = "tract", 
                variables = "B01003_001E", 
                year = 2017, 
                state = "MA", 
                county = "Middlesex", 
                geometry = TRUE, 
                keep_geo_vars = FALSE, 
                survey = "acs5") %>% 
  rename_all(tolower) %>%
  rename(pop = estimate) %>%
  select(-c("moe", "variable")) %>%
  st_transform(2249) %>%
  mutate(
    tot_area = as.numeric(st_area(geometry))
  )

stop_pops <- stops[pops,] %>%
  st_buffer(dist=2640) %>%
  st_intersection(pops) %>%
  mutate(
    int_area = as.numeric(st_area(geometry)),
    pop_prop = pop * int_area/tot_area
  ) %>%
  group_by(address) %>%
  summarize(
    name = first(name),
    municipality = first(municipality),
    pop_est = sum(pop_prop)
  )