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https://github.com/mapbox/shp-write

create and write to shapefiles in pure javascript
https://github.com/mapbox/shp-write

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create and write to shapefiles in pure javascript

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# 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](https://github.com/tmcw/dbf)
for the data component, and [jsZIP](http://stuk.github.io/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](http://caniuse.com/#feat=typedarrays)
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](https://github.com/Stuk/jszip/issues/53) so it uses STORE instead of DEFLATE.

## Minimal Example

```js
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

```js
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](http://www.opengeospatial.org/standards/wkt-crs) in the .prj file to define a different projection the prj option can be used:

```js
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

```js
{
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](http://geojson.org/) 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