README

Optimized data of Brazil municipalities borders.

Used in the Você bebe agrotóxicos? Descubra se a água da sua torneira foi contaminada data visualization, on pesticides in Brazil.

Data

data/br-px-topo.json: optimized Brazil geometries for municipalities in Brazil.

{
  "type":	"Topology",
  "bbox": {
    "0": 5.684341886080802e-14,
    "1": 47.00178093080447,
    "2": 960,
    "3": 912.9982190691954
  },
  "transform"	: {
    "scale":	[…],
    "translate":	[…]
  },
  "objects": {
    "municipalities": {
      "type":	"GeometryCollection",
      "geometries":	[…]},
    "republic":	{…},
    "federative-units":	{…},
    "internal-federative-units":	{…}
  },
  "arcs":	[…]
}

Municipalities

The data contain the geographic limits of the Brazil municipalities, as defined by the official Brazilian institute (IPGE), as well as some metadata. For example, for the Abadia de Goiás municipality:

cat data/br-px-topo.json | jq '.objects.municipalities.geometries[0]'
{
  "type": "Polygon",
  "arcs": [
    [
      0,
      1,
      2,
      3,
      4
    ]
  ],
  "properties": {
    "ibgeCode": "520005",
    "fu": "GO",
    "fuCode": "52",
    "name": "Abadia de Goiás",
    "population": "8207"
  }
}

with:

"type": the type of spatial data as defined in topojson
"arcs": the arcs of the topological data used to define the border (see the topojson specification)
"ibgeCode": municipality identifier given by IBGE
"fu": two-letter federal unit (state) identifier given by IBGE
"fuCode": two-number federal unit (state) identifier given by IBGE
"name": name of the municipality
"population": estimated population (source IBGE 2018)

States

To get access to the states data:

cat data/br-px-topo.json | jq '.objects["federative-units"].geometries[0]'

{
  "type": "MultiPolygon",
  "arcs": [
    [
      [
        7417,
        -14108,
        ...
      ],
      [
        15582,
        11956
      ],
      [
        3820,
        17112
      ]
    ]
  ],
  "id": "52",
  "properties": {
    "fu": "GO",
    "fuCode": "52"
  }
}

The metadata only include the state identifiers.

Note that the internal borders between states, ie. excluding the national frontier, are also provided (to be used for graphical purposes) by:

cat data/br-px-topo.json | jq '.objects["internal-federative-units"].geometries[0]'

The national frontier is also available as a MULTIPOLYGON with:

cat data/br-px-topo.json | jq '.objects["republic"].geometries[0]'

Rebuild the data

To update the data/br-px-topo.json file, first install the required Node.js packages:

npm install

then launch the Makefile

make all

Use make clean to remove files.

Alternately, use the npm scripts:

npm run clean
npm run build

Methodology

The methodology is described in the Makefile comments.

get and unzip the municipalities spatial data from IBGE ftp (shapefile)
convert shapefile to GeoJSON
project GeoJSON to EPSG:5530, so treatments are done in pixels, in a 960x960 px square, instead of steradians
convert JSON to ND JSON for easier manipulation
add IBGE code property
on another side, convert inputs/population.csv file to ND JSON format
merge population data with spatial data, adding the ibgeCode, fu, fuCode, name and population properties
convert ND JSON to TopoJSON, with geometries in municipalities topology object
simplify the geometry (in order to reduce the size of the file), removing the "triangle areas" below 1px² (see Line Simplification)
quantize the values, removing useless decimals (in order to reduce the size of the file)
add republic, federative-units (states) and internal-federative-units geometries

Technology used

npm to install the required packages: d3-dsv, d3-geo-projection, ndjson-cli, shapefile and topojson
Makefile to coordinate the data building processes

Based on the work by

Mike Bostock, https://medium.com/@mbostock/command-line-cartography-part-1-897aa8f8ca2c parts 1, 2, 3 and 4.
Carolina Bigonha, https://github.com/carolinabigonha/br-atlas/
Philippe Rivière, https://observablehq.com/@fil/epsg-5530
IBGE, ftp://geoftp.ibge.gov.br/organizacao_do_territorio

DevAndreAkira / pesticides_website_data