shp-write-spatialreference

shp-write

ANNOUNCEMENT!

The npm package location (and subsequently unpkg url) for this repo has changed!

tl;dr: shp-write -> @mapbox/shp-write

Writes shapefile in pure javascript. Uses dbf for the data component, and jsZIP to generate ZIP file downloads in-browser.

Usage

For npm

npm install --save @mapbox/shp-write

Yarn

yarn add @mapbox/shp-write

Or in a browser

https://unpkg.com/@mapbox/shp-write@latest/shpwrite.js

Caveats

• Requires a capable fancy modern browser with Typed Arrays support
• Geometries: Point, LineString, Polygon, MultiLineString, MultiPolygon
• Tabular-style properties export with Shapefile's field name length limit
• Uses jsZip for ZIP files, but compression is buggy so it uses STORE instead of DEFLATE.

Minimal Example

var shpwrite = require("@mapbox/shp-write");

// a GeoJSON bridge for features
const zipData = shpwrite.zip(
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        geometry: {
          type: "Point",
          coordinates: [0, 0],
        },
        properties: {
          name: "Foo",
        },
      },
      {
        type: "Feature",
        geometry: {
          type: "Point",
          coordinates: [0, 10],
        },
        properties: {
          name: "Bar",
        },
      },
    ],
  }
);

Options Example

var shpwrite = require("@mapbox/shp-write");

const options = {
  folder: "my_internal_shapes_folder",
  filename: "my_zip_filename",
  outputType: "blob",
  compression: "DEFLATE",
  types: {
    point: "mypoints",
    polygon: "mypolygons",
    polyline: "mylines",
  },
};

// a GeoJSON bridge for features
const zipData = shpwrite.zip(
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        geometry: {
          type: "Point",
          coordinates: [0, 0],
        },
        properties: {
          name: "Foo",
        },
      },
      {
        type: "Feature",
        geometry: {
          type: "Point",
          coordinates: [0, 10],
        },
        properties: {
          name: "Bar",
        },
      },
    ],
  },
  options
);

Custom .prj file

To pass a custom WKT string in the .prj file to define a different projection the prj option can be used:

var options = {
    prj: 'PROJCS["Amersfoort / RD New",GEOGCS["Amersfoort",DATUM["D_Amersfoort",SPHEROID["Bessel_1841",6377397.155,299.1528128]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Stereographic_North_Pole"],PARAMETER["standard_parallel_1",52.15616055555555],PARAMETER["central_meridian",5.38763888888889],PARAMETER["scale_factor",0.9999079],PARAMETER["false_easting",155000],PARAMETER["false_northing",463000],UNIT["Meter",1]]'
}

API

write(data, geometrytype, geometries, callback)

Given data, an array of objects for each row of data, geometry, the OGC standard geometry type (like POINT), geometries, a list of geometries as bare coordinate arrays, generate a shapfile and call the callback with err and an object with

{
    shp: DataView(),
    shx: DataView(),
    dbf: DataView()
}

zip(geojson, [options])

Generate a ArrayBuffer of a zipped shapefile, dbf, and prj, from a GeoJSON object.

DEPRECTEAD! May be removed in a future version

download(geojson, [options])

Given a GeoJSON FeatureCollection as an object, converts convertible features into Shapefiles and triggers a download.

The additional options parameter is passed to the underlying zip call.

This is now marked as deprecated because it applies to browsers only and the user should instead rely on an external library for this functionality like file-saver or downloadjs

Other Implementations

• https://code.google.com/p/pyshp/

Reference

• http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf

Contributors

• Nick Baugh [e-mail]