popdat/
distribute_people.rs

1use geo::{Area, BooleanOps, Contains};
2use rand::Rng;
3use rand_xorshift::XorShiftRng;
4
5use abstutil::prettyprint_usize;
6use map_model::{BuildingID, Map};
7
8use crate::{CensusArea, CensusPerson, Config};
9
10pub fn assign_people_to_houses(
11    areas: Vec<CensusArea>,
12    map: &Map,
13    rng: &mut XorShiftRng,
14    _config: &Config,
15) -> Vec<CensusPerson> {
16    let mut people = Vec::new();
17    for area in areas {
18        for (home, n) in distribute_population_to_homes(area.polygon, area.population, map, rng) {
19            for _ in 0..n {
20                people.push(CensusPerson {
21                    home,
22                    // TODO Making this up for now. We can either move this to Config or see if we
23                    // can extract it from the census. Also, not even sure which of these
24                    // attributes are useful later in the pipeline.
25                    age: rng.gen_range(5..95),
26                    employed: rng.gen_bool(0.7),
27                    owns_car: rng.gen_bool(0.5),
28                });
29            }
30        }
31    }
32    people
33}
34
35/// Starting from some number of total people living in a polygonal area, randomly distribute them
36/// to residential buildings within that area. Returns a list of homes with the number of residents
37/// in each.
38pub fn distribute_population_to_homes(
39    polygon: geo::Polygon,
40    population: usize,
41    map: &Map,
42    rng: &mut XorShiftRng,
43) -> Vec<(BuildingID, usize)> {
44    let map_boundary = geo::Polygon::from(map.get_boundary_polygon().clone());
45    let bldgs: Vec<map_model::BuildingID> = map
46        .all_buildings()
47        .iter()
48        .filter(|b| {
49            polygon.contains(&geo::Point::from(b.label_center)) && b.bldg_type.has_residents()
50        })
51        .map(|b| b.id)
52        .collect();
53
54    // If the area is partly out-of-bounds, then scale down the number of residents linearly
55    // based on area of the overlapping part of the polygon.
56    let pct_overlap = polygon.intersection(&map_boundary).unsigned_area() / polygon.unsigned_area();
57    let num_residents = (pct_overlap * (population as f64)) as usize;
58    debug!(
59        "Distributing {} residents to {} buildings. {}% of this area overlapped with the map, \
60         scaled residents accordingly.",
61        prettyprint_usize(num_residents),
62        prettyprint_usize(bldgs.len()),
63        (pct_overlap * 100.0) as usize
64    );
65
66    // How do you randomly distribute num_residents into some buildings?
67    // https://stackoverflow.com/questions/2640053/getting-n-random-numbers-whose-sum-is-m
68    // TODO Problems:
69    // - Because of how we round, the sum might not exactly be num_residents
70    // - This is not a uniform distribution, per stackoverflow
71    // - Larger buildings should get more people
72
73    let mut count_per_home = Vec::new();
74    let mut rand_nums: Vec<f64> = (0..bldgs.len()).map(|_| rng.gen_range(0.0..1.0)).collect();
75    let sum: f64 = rand_nums.iter().sum();
76    for b in bldgs {
77        let n = (rand_nums.pop().unwrap() / sum * (num_residents as f64)) as usize;
78        count_per_home.push((b, n));
79    }
80    count_per_home
81}
popdat/distribute_people.rs

popdat/
distribute_people.rs
