I'm a professor of mathematics at the University of North Carolina Asheville. I've also done a fair amount of consulting work over the years focusing on scientific and data visualization.
I'm happy to be part of the first Observable Ambassador's cohort.
{
if (all_results.length > 0) {
return setup_hexmap(all_results.slice(-1)[0].precincts);
} else {
return "Re-execute the code block below (after some legal maps have been generated) to see the most recently generated districts.";
}
}
unique_groups = {
let groups = d3.group(
all_results, // .filter((o) => o.minority_cnt >= 2),
(o) => o.yellow_cnt
);
let grouped_unique = new Map();
let keys = Array.from(groups.keys()).sort();
keys.forEach((k) =>
grouped_unique.set(
k,
_.uniqBy(groups.get(k), districts_to_unique_id).slice(0, 239)
)
);
return grouped_unique;
}
improve2(unique_groups.get(4)[0], "purple")
{
if (improved) {
return setup_hexmap(improved.precincts);
} else {
return setup_hexmap(
(await FileAttachment("improved_yellow_5to6.json").json()).precincts
);
}
}
improved
// setup_hexmap(all_results[0].precincts)
// all_results.slice(0, 2).map(async function (r) {
// if (r.purple_cnt > r.yellow_cnt) {
// let improved = await improve_more(r, "purple", 200);
// if (improved.purple_cnt > r.purple_cnt) {
// // all_results.push(improved);
// return improved;
// }
// }
// })
// setup_hexmap(five_to_six[14].precincts)
setup_hexmap(five_to_six[12].precincts)
new_results
new_results = []
five_to_six.filter((o) => o.yellow_cnt == 6)
seven_to_eight.filter((o) => o.purple_cnt == 8)
// seven_to_eight = Promise.all(
// unique_groups
// .get(3)
// .slice(0, 40)
// .map((r) =>
// r.purple_cnt > r.yellow_cnt
// ? improve2(r, "purple")
// : improve2(r, "yellow")
// )
// )
setup_hexmap(seven_to_eight[1].precincts)
unique_groups
improved = {
if (results[1].precincts) {
return improve_more(results[2], "yellow", 500);
}
}
// This file contains just the initial map and dummy yellow and
// purple maps that will be overwritten by the code.
results = (reset, FileAttachment("hexapolis_init.json").json())
all_results = (reset, [])
// all_results = FileAttachment("five_thirty_eight.json").json()
function districts_to_unique_id(p) {
let districts = d3.group(p.precincts, (o) => o.district);
return d3
.range(1, 10)
.map((i) =>
districts
.get(i)
.map((o) => [o.i, o.j])
.sort()
)
.sort()
.flat(2)
.map((i) => (i < 10 ? `0${i}` : `${i}`))
.join("");
}
all_results
d3.sum(Array.from(unique_groups.values()).map((a) => a.length))
Array.from(unique_groups.values()).flat()
state = (reset,
{
button_pushes: 0,
button_text: ["Start random redistricting", "Stop random redistricting"]
})
intervalIDs = []
function random_precincts(optimize_color = false) {
let assoc = new Map();
assoc.set(undefined, 1);
let precincts;
while (assoc.has(undefined)) {
precincts = all_indices.map(([i, j]) => ({
id: `precinct_${i}_${j}`,
i: i,
j: j,
color: pair_in_array([i, j], purple) ? "purple" : "yellow",
minority: pair_in_array([i, j], minorities) ? true : false,
neighbors: [
[i - 1, j],
[i + 1, j],
[i, j - 1],
[i, j + 1],
[i - 1, j + 1],
[i + 1, j - 1]
]
.filter(([i0, j0]) => pair_in_array([i0, j0], all_indices))
.map(([i0, j0]) => `precinct_${i0}_${j0}`)
}));
// Failed
// let so_far = get_first_15();
// so_far.forEach((p) => (p.district = 1));
let so_far = [];
for (let i = 1; i <= 9; i++) {
try {
let boundary = get_boundary_precincts(so_far, precincts);
let new15 = get15(boundary, so_far, precincts);
so_far = so_far.concat(new15);
new15.forEach((p) => (p.district = i));
} catch (e) {
("pass");
}
}
assoc = d3.group(precincts, (o) => o.district);
}
let groups = d3.group(precincts, (p) => p.district);
let purple_cnt = 0;
let yellow_cnt = 0;
let minority_cnt = 0;
groups.forEach(function (g) {
if (g.filter((p) => p.minority).length > 7) {
minority_cnt++;
}
let gg = d3.group(g, (p) => p.color);
let p = gg.get("purple");
let y = gg.get("yellow");
if (!y) {
purple_cnt++;
} else if (p && p.length > y.length) {
purple_cnt++;
} else {
yellow_cnt++;
}
});
let new_result = { purple_cnt, yellow_cnt, minority_cnt, precincts };
return new_result;
}
results
function get_boundary_precincts(deleted, precincts) {
let remaining = set_difference(precincts, deleted);
let deleted_ids = deleted.map((o) => o.id);
return remaining.filter(
(o) =>
o.neighbors.length < 6 ||
_.intersection(
deleted_ids,
o.neighbors.map((o) => o.id)
).length > 0
);
}
get15([all_precincts[3]], [], all_precincts)
function get15(start, avoid, all_precincts) {
let precincts_left = set_difference(all_precincts, avoid);
let precincts_start = set_difference(start, avoid);
// let output = [precincts_start[random(0, precincts_start.length)()]];
let output = [random_choice(precincts_start)];
//let output = [random_choice(precincts_left)];
let cnt = 0;
while (output.length < 15 && cnt++ < 16) {
let neighbors = set_difference(
get_all_neighbors(output, all_precincts),
avoid
);
output = output.concat(neighbors);
if (output.length > 15) {
console.log(output.length);
output = output.slice(0, 15);
} else if (cnt > 12) {
throw "Not found";
}
}
return output;
}
async function improve_more(input, color, n) {
let current = _.cloneDeep(input);
for (let i = 0; i < n; i++) {
await Promises.delay().then(function () {
let this_try = improve(current, color);
let indicator1 =
color == "purple" ? current.purple_cnt : current.yellow_cnt;
let indicator2 =
color == "purple" ? this_try.purple_cnt : this_try.yellow_cnt;
if (indicator1 < indicator2) {
current = this_try;
current.improvement_iterations = i;
}
});
}
return current;
}
// setup_hexmap(all_results[2].precincts)
// setup_hexmap(atry.precincts)
console.log("-----")
// atry = improve2(all_results[3], "yellow")
function improve2(input, color) {
let best_result = _.cloneDeep(input);
let precincts = _.cloneDeep(best_result.precincts);
for (let i = 0; i < 500; i++) {
let precincts0 = _.cloneDeep(precincts);
let districts0 = d3.group(precincts0, (p) => p.district);
let choice1 = random(1, 9)();
let district1 = districts0.get(choice1);
let choice2 = random(choice1 + 1, 10)();
let district2 = districts0.get(choice2);
let border12 = get_border(choice1, choice2, precincts0);
if (border12.length > 0) {
let border21 = get_border(choice2, choice1, precincts0);
let p1 = border12[random(0, border12.length)()];
p1.district = choice2;
let p2 = border21[random(0, border21.length)()];
p2.district = choice1;
let new_district1 = precincts0.filter((o) => o.district == choice1);
let rest1 = set_difference(precincts0, new_district1);
let test1;
try {
test1 = get15([new_district1[0]], rest1, precincts0).length == 15;
} catch {
test1 = false;
}
let new_district2 = precincts0.filter((o) => o.district == choice2);
let rest2 = set_difference(precincts0, new_district2);
let test2;
try {
test2 = get15([new_district2[0]], rest2, precincts0).length == 15;
} catch {
test2 = false;
}
if (test1 && test2) {
precincts = precincts0;
let groups = d3.group(precincts, (p) => p.district);
let purple_cnt = 0;
let yellow_cnt = 0;
let minority_cnt = 0;
groups.forEach(function (g) {
if (g.filter((p) => p.minority).length > 7) {
minority_cnt++;
}
let gg = d3.group(g, (p) => p.color);
let p = gg.get("purple");
let y = gg.get("yellow");
if (!y) {
purple_cnt++;
} else if (p && p.length > y.length) {
purple_cnt++;
} else {
yellow_cnt++;
}
});
if (minority_cnt >= 2) {
let new_result = {
purple_cnt,
yellow_cnt,
minority_cnt,
precincts
};
new_results.push(new_result);
// let indicator1 =
// color == "purple" ? best_result.purple_cnt : best_result.yellow_cnt;
// let indicator2 = color == "purple" ? purple_cnt : yellow_cnt;
// if (indicator1 < indicator2) {
// best_result = new_result;
// }
if (
score(best_result.precincts, color) <
score(new_result.precincts, color)
) {
best_result = new_result;
}
}
}
}
}
return best_result;
function get_border(i, j, precints_in) {
let groups = d3.group(precints_in, (p) => p.district);
let jids = groups.get(j).map((p) => p.id);
return groups
.get(i)
.filter((p) => _.intersection(p.neighbors, jids).length > 0);
}
}
function improve(input, color) {
let changed = false;
let precincts = _.cloneDeep(input.precincts);
for (let i = 0; i < random(16, 32)(); i++) {
let precincts0 = _.cloneDeep(precincts);
let districts0 = d3.group(precincts0, (p) => p.district);
let choice1 = random(1, 9)();
let district1 = districts0.get(choice1);
let choice2 = random(choice1 + 1, 10)();
let district2 = districts0.get(choice2);
let border12 = get_border(choice1, choice2, precincts0);
if (border12.length > 0) {
let border21 = get_border(choice2, choice1, precincts0);
let p1 = border12[random(0, border12.length)()];
p1.district = choice2;
let p2 = border21[random(0, border21.length)()];
p2.district = choice1;
let new_district1 = precincts0.filter((o) => o.district == choice1);
let rest1 = set_difference(precincts0, new_district1);
let test1;
try {
test1 = get15([new_district1[0]], rest1, precincts0).length == 15;
} catch {
test1 = false;
}
let new_district2 = precincts0.filter((o) => o.district == choice2);
let rest2 = set_difference(precincts0, new_district2);
let test2;
try {
test2 = get15([new_district2[0]], rest2, precincts0).length == 15;
} catch {
test2 = false;
}
if (test1 && test2) {
precincts = precincts0;
// atry.push(precincts);
}
}
}
let groups = d3.group(precincts, (p) => p.district);
let purple_cnt = 0;
let yellow_cnt = 0;
let minority_cnt = 0;
groups.forEach(function (g) {
if (g.filter((p) => p.minority).length > 7) {
minority_cnt++;
}
let gg = d3.group(g, (p) => p.color);
let p = gg.get("purple");
let y = gg.get("yellow");
if (!y) {
purple_cnt++;
} else if (p && p.length > y.length) {
purple_cnt++;
} else {
yellow_cnt++;
}
});
let original_score, new_score;
// let idx = color == "purple" ? 1 : 2;
if (minority_cnt >= 2) {
// original_score = score(results[idx].precincts, color);
// new_score = score(precincts, color);
// if (original_score < new_score) {
let indicator1 = color == "purple" ? input.purple_cnt : input.yellow_cnt;
let indicator2 = color == "purple" ? purple_cnt : yellow_cnt;
if (indicator1 < indicator2) {
// results[idx].precincts = precincts;
// results[idx].purple_cnt = purple_cnt;
// results[idx].yellow_cnt = yellow_cnt;
// results[idx].minority_cnt = minority_cnt;
changed = true;
}
}
if (changed) {
return {
purple_cnt,
yellow_cnt,
minority_cnt,
precincts
};
} else {
return input;
}
// return [choice1, choice2, district1, district2];
function get_border(i, j, precints_in) {
let groups = d3.group(precints_in, (p) => p.district);
let jids = groups.get(j).map((p) => p.id);
return groups
.get(i)
.filter((p) => _.intersection(p.neighbors, jids).length > 0);
}
}
function score(precincts, color) {
let groups = d3.group(precincts, (p) => p.district);
let purple_proportions = [];
let yellow_proportions = [];
let minority_cnt = 0;
groups.forEach(function (g) {
if (g.filter((p) => p.minority).length > 7) {
minority_cnt++;
}
let gg = d3.group(g, (p) => p.color);
let p = gg.get("purple");
let y = gg.get("yellow");
if (!y) {
purple_proportions.push(1);
} else if (!p) {
yellow_proportions.push(1);
} else if (p.length > y.length) {
purple_proportions.push(p.length / 15);
} else {
yellow_proportions.push(y.length / 15);
}
});
if (minority_cnt >= 2) {
if (color == "yellow") {
return (
yellow_proportions.length -
2 * d3.mean(yellow_proportions) +
d3.mean(purple_proportions)
);
} else if (color == "purple") {
return (
purple_proportions.length -
2 * d3.mean(purple_proportions) +
d3.mean(yellow_proportions)
);
}
} else {
return 0;
}
}
// Version that generates crazier shapes but never seems to
// generate 9 separate districts
function get_first_15() {
// let precincts_left = set_difference(all_precincts, avoid);
// let precincts_start = set_difference(start, avoid);
// let output = [precincts_start[random(0, precincts_start.length)()]];
// let output = [random_choice(precincts_start)];
let output = [random_choice(all_precincts)];
let cnt = 0;
while (output.length < 15 && cnt++ < 16) {
let neighbors = get_all_neighbors(output, all_precincts);
// console.log(neighbors);
output.push(random_choice(neighbors));
if (output.length > 15) {
output = output.slice(0, 15);
} else if (cnt > 16) {
throw "Not found";
}
}
return output;
}
function get_all_neighbors(input_precincts, all_precincts) {
let inputs_ids = input_precincts.map((o) => o.id);
let all_neighbor_ids = input_precincts
.map((o) => o.neighbors)
.flat()
.filter((id) => inputs_ids.indexOf(id) == -1);
let all_neighbors = Array.from(new Set(all_neighbor_ids)).map(
(id) => all_precincts.filter((o) => o.id == id)[0]
);
return all_neighbors;
}
function set_difference(in_set, out_set) {
return in_set.filter((o) => out_set.map((p) => p.id).indexOf(o.id) == -1);
}
function pair_in_array([i, j], A) {
return _.findIndex(A, (pair) => pair[0] == i && pair[1] == j) > -1;
}
function random_choice(list) {
let c = random(0, list.length)();
return list[c];
}
random = {
reset;
let random = d3.randomInt;
let source = d3.randomLcg(s);
random = random.source(source);
return random;
}
import {
all_indices,
purple,
yellow,
minorities,
setup_hexmap,
all_precincts
} from "@mcmcclur/setting-up-hexapolis"
polygonClipping = require("polygon-clipping")
all_results
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
