28:null 29:["$","title",null,{"children":"1950 Census API | Benjamin Schmidt | Observable"}] 2e:[] 2c:{"id":"226aff7efe01abde","slug":"1950-census-api","title":"1950 Census API","thumbnail":"3b8505f49b40d25faa38a85442f1085cfb35ebac80d09cce85b3de99f47bca7c","access_level":"public","create_time":"$D2022-04-02T21:26:53.928Z","update_time":"$D2022-04-06T00:41:56.378Z","view_time":null,"first_public_time":"$D2022-04-04T00:09:11.493Z","has_unpublished_edits":null,"fork":false,"stars":7,"starred":false,"owner":{"type":"team","id":"18bbeceb36c8f564","login":"bmschmidt","name":"Benjamin Schmidt","avatar_url":"https://avatars-next.observableusercontent.com/addc2adb5ec95cc72a64820e4a08488bad5d48d95a895eef85a45b136ed66792","tier":"starter_2024"},"version":359,"publish_version":359,"role":null,"authored":false,"authors":[{"type":"individual","id":"33354ca265b21f01","login":"bmschmidt","name":"Benjamin Schmidt","avatar_url":"https://avatars-next.observableusercontent.com/addc2adb5ec95cc72a64820e4a08488bad5d48d95a895eef85a45b136ed66792","tier":null}],"members":[{"type":"individual","id":"33354ca265b21f01","login":"bmschmidt","name":"Benjamin Schmidt","avatar_url":"https://avatars-next.observableusercontent.com/addc2adb5ec95cc72a64820e4a08488bad5d48d95a895eef85a45b136ed66792","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":4,"collection":null,"type":"notebook","body":{"title":"1950 Census API","cells":[{"id":0,"value":"# 1950 Census API\n\nThe newly-released 1950 Census website exposes an API for retrieving metadata, images, and names that is not documented but quite useful. Here I'll describe some of what it does.\n\nThis is a work in progress--forks, edits, suggestions welcome.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":357,"value":"img = {\n var img = new Image()\n img.src = `${image_manifest}/full/,512/0/default.jpg`\n img.crossOrigin = 'Anonymous'\n img.setAttribute('crossOrigin', '');\n\n await img.decode()\n return img\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":20,"value":"## County Listings\n\nI don't understand what a 'county' is in the Census listings, but I don't need to--the API query `/county?state=${state}` returns a list of counties in a state.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":22,"value":"viewof state = Inputs.select(linear_us_state_order.filter(d => d.length==2), {label: \"State\", value: \"KS\"})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":330,"value":"import { linear_us_state_order } from '@bmschmidt/useful-linear-orders-for-countries-and-states'","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":25,"value":"viewof county = {\n const counties = await counties_in_state(state)\n return Inputs.select(counties, {label: \"county\", value: counties[Math.floor(Math.random() * counties.length)]})\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":339,"value":"counties_in_state = function(state) {return fetch(`https://bmschmidt-cors-observable.herokuapp.com/https://1950census.archives.gov/api/county?state=${state}&size=1000`).then(d => d.json())}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":39,"value":"md`## ED Lists within counties\n\nOnce you have a state and county combination, it is possible to page through results to get a list of all enumeration districts.\n

\nhttps://1950census.archives.gov/api/search?county=\\${county}&page=1&state=\\${state}&size=250&page=\\${page_now}\n

\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":34,"value":"eds = {\n let total = 1\n let page_now = 1\n let all_results = []\n while (all_results.length < total) {\n const r = await fetch(`https://bmschmidt-cors-observable.herokuapp.com/https://1950census.archives.gov/api/search?county=${county}&page=1&state=${state}&size=250&page=${page_now}`).then(d => d.json())\n total = r.total\n all_results = [...all_results, ...r.results]\n page_now += 1\n }\n return all_results\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":49,"value":"viewof ed = Inputs.select(d3.rollup(eds, v => v[0], d => d.description))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":70,"value":"md`# Manifests within an enumeration district\n\nEach portion of an enumeration district has an identifier that represents, essentially, a *roll* of images. This information is presented as a IIIF *presentation* manifest; inside of the presentation manifest, at \\`.sequences[0].canvases\\`, is a list of the individual page images.\n\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":44,"value":"presentation_manifest = fetch(`https://bmschmidt-cors-observable.herokuapp.com/https://1950census.archives.gov/api/manifest?state=${state}&ed=${ed.ed}`).then(d => d.json())","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":84,"value":"image_manifests = presentation_manifest.sequences[0].canvases.map(d => d.images[0].resource['@id']).map(d => d.replace(/\\/full.*/, \"\"))","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":78,"value":"## Images within a manifest\n\nNow we're in [IIIF-land](https://iiif.io), where all sorts of transformations are possible through URL manipulation. A single image from this page looks like this:","pinned":true,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":114,"value":"i = {\n for (let i=0; i>=0;) {\n if (animate === \"animate\") {\n i++\n }\n yield await Promises.delay(1000, i)\n }\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":139,"value":"{\n if (animate === \"animate\") {set(viewof image_manifest, image_manifests[i % image_manifests.length])}\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":107,"value":"viewof image_manifest = Inputs.radio(new Map(image_manifests.map((d, i) => [i, d])), {value: image_manifests[0]})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":178,"value":"viewof animate = Inputs.radio([\"animate\", \"stop that annoying animation!\"], {value: \"animate\"})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":211,"value":"md`# Image Rotation\n\nThe images below show x and y density histograms below them. These could be useful for aligning images and extracting boxes.\n`","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":194,"value":"viewof angle = Inputs.range([-Math.PI / 64, Math.PI/64], {label: \"angle\"})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":285,"value":"html`

${right}

${ctx.canvas}

${bottom}

`","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":282,"value":"bottom = Plot.plot({\n width: 512,\n height: 150,\n marks: [\n Plot.lineY([...histograms.w].map(d => {return {x : d}}), {y: \"x\"}),\n ]\n})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":273,"value":"right = Plot.plot({\n height: 552,\n width: 250,\n marks: [\n Plot.lineX([...histograms.h].reverse().map(d => {return {y : d}}), {x: \"y\"})\n\n ]\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":256,"value":"[...histograms.w].map(d => {return {x : d}})","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":175,"value":"histograms = {\n redraw\n const d = ctx.getImageData(0,0, 512, 512).data\n const w = new Float32Array(512)\n const h = new Float32Array(512)\n for (let i = 0; i < 512 * 512 * 4; i += 4) {\n const alpha = (255 - d[i]) * d[i + 3] /255\n \n const x = 512 - Math.floor(i/4/512)\n const y = (i / 4) % 512\n h[x] += alpha\n w[y] += alpha\n }\n return {w, h} \n\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":5,"value":"ctx = DOM.context2d(512, 512);\n","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":186,"value":"redraw = {\n const {width, height} = img;\n ctx.clearRect(0, 0, 512, 512)\n ctx.translate(256, 256);\n ctx.rotate(angle);\n ctx.drawImage(img, -width / 2, -height / 2, width, height);\n ctx.rotate(-angle);\n ctx.translate(-256, -256);\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":214,"value":"img.height","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":52,"value":"d3 = require(\"d3@v7\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":122,"value":"function set(input, value) {\n input.value = value;\n input.dispatchEvent(new Event(\"input\"));\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W2e","stdlib":"1","titling":"auto"}} 2d:"$2c:body"