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https://github.com/koopjs/winnow
Deprecated
https://github.com/koopjs/winnow
deprecated geojson in-memory-database sql typesript
Last synced: 17 days ago
JSON representation
Deprecated
- Host: GitHub
- URL: https://github.com/koopjs/winnow
- Owner: koopjs
- License: apache-2.0
- Created: 2016-02-19T19:14:26.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2023-08-13T20:04:33.000Z (over 1 year ago)
- Last Synced: 2024-08-10T04:59:53.922Z (3 months ago)
- Topics: deprecated, geojson, in-memory-database, sql, typesript
- Language: JavaScript
- Homepage:
- Size: 28.1 MB
- Stars: 90
- Watchers: 16
- Forks: 18
- Open Issues: 15
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# Winnow
## DEPRECATED - now migrated to a package in the [Koop monorepo](https://github.com/koopjs/koop/). Update any `npm` usage to `@koopjs/winnow`.
[](http://unmaintained.tech/)
[![npm version][npm-img]][npm-url]
[![js-standard-style][standard-img]][standard-url]
[![Greenkeeper badge][greenkeeper-image]][greenkeeper-url]
*Winnow* is made for applying sql to geojson in memory. It is useful for working against geojson objects but also has built-in primitives for piping streams.
# API
## `winnow.query`
Build and apply a query to a feature collection object or an array of features
```javascript
const features = Object
const options = {
where: String // A sql where statement
geometry: Object // GeoJSON or Esri geometry Object
spatialPredicate: String // ST_Within || ST_Contains || ST_Intersects
fields: Array // Set of fields to select from feature properties
aggregates: Object // Describes the set of aggregations to perform on fields
groupBy: Array // Set of fields for grouping statistics
limit: Number // number of results to return
offset: Number // number of return features to offset
order: Array // Set of fields or aggregates by which to order results
outputCrs: Number || String // An EPSG code, an OGC WKT or an ESRI WKT used to convert geometry
inputCrs: Number || String // An EPSG code, an OGC WKT or an ESRI WKT defining the coordinate system of the input data. Defaults to 4326 (WGS84)
toEsri: Boolean // return Esri feature collection
geometryPrecision: Number // number of digits to appear after decimal point for geometry
classification: Object // GeoJSON or geoservices classification Object
}
winnow.query(features, options)
// Returns the set of features that match the query
```
### `where`
A sql where statement.
- `'Trunk_Diameter > 10'`
- `'Trunk_Diameter > 10 AND Genus like 'Quercus%'`
- `(Genus like '%Quercus%' OR Common_Name like '%Live Oak%') AND Street_Type like '%AVE%'`
### `geometry`
A GeoJSON or Esri Geometry Object
```javascript
// GeoJSON Polygon
{
type: 'Polygon',
coordinates: [[[-118.163, 34.162], [-118.108, 34.162], [-118.108, 34.173], [-118.163, 34.173], [-118.163, 34.162]]],
}
// Esri Envelope (aka Bounding box)
{
xmin: -13155799.066536672,
ymin: 4047806.77771083,
xmax: -13143569.142011061,
ymax: 4050673.16627152,
spatialReference: {
wkid: 102100
}
}
```
### `spatialPredicate`
Specifies the relationship between the passed-in geometry and the features in the data
- ST_Within: Features in the data must be completely within the passed-in geometry
- ST_Contains: Features in the data must completely contain the passed-in geometry
- ST_Intersects: Features in the data must intersect the passed-in geometry
Can also specify the esri-style predicates `esriSpatialRelWithin, esriSpatialRelContains, esriSpatialRelIntersects`
### `fields`
An array that specifies fields should be returned from each features properties or attributes. Will also accept a comma-delimited string.
e.g. `[Trunk_Diameter, Common_Name, Genus]`
### `aggregates`
An array that specifies aggregations to apply across all features or properties. Must specify at least a type and a field. Providing a name for the aggregation is optional
Types: `[sum, avg, count, max, min, first, last]`
e.g:
```javascript
[
{
type: 'sum',
field: 'Trunk_Diameter',
name: 'Total_Trunk_Diameter'
},
{
type: 'avg',
field: 'Trunk_Diameter'
}
]
```
### `groupBy`
An array of fields used to group the results. Must be used with aggregates. Note this will not return any geometry
### `limit`
The total number of results to return
### `offset`
The amount to offset returned features (e.g., `10` will skip the first 10 returned features). `limit` is required to used `offset`.
### `order`
An array of fields use to sort the output
### `outputCrs` (formerly `projection`)
Can be an EPSG code, an OGC wkt or an Esri wkt. This parameter controls how the geometry will be projected to another coordinate system.
### `inputCrs`
Can be an EPSG code, an OGC wkt or an Esri wkt.. This parameter defines the coordinate system of input data. If the incoming data is a GeoJSON feature collection with a "named" `crs` property defined according to [specification](https://geojson.org/geojson-spec#named-crs), winnow will use it's value if `inputCrs` is undefined. If neither is defined, Winnow assumes the input data has coordinate system WGS84.
### `toEsri`
If true, the object returned will be an esri feature collection.
Winnow will automatically determine field types from the first feature passed in. If a given attribute is null, Winnow will assume it is a string.
You can also pass in a metadata object that describes the fields in the feature collection. This is recommended if you know your schema ahead of time
e.g.
```javascript
{
type: 'FeatureCollection',
features: [],
metadata: {
fields: [
{
name: 'SomeDateField',
type: 'Date'
},
{
name: 'SomeDoubleField',
type: 'Double'
},
{
name: 'SomeIntegerField',
type: 'Integer'
},
{
name: 'SomeStringField',
type: 'String'
}
]
}
}
```
### `geometryPrecision`
A number for geometry precision. Geometry values will be truncated to the supplied decimal place.
### `classification`
An object for classification aggregation. Classification ouputs an array of breaks on features. There are two supported classification types: _Class Breaks_ and _Unique Value_. Classification supports input from FeatureServer's [generateRenderer](https://github.com/FeatureServer/FeatureServer#generateRenderer) _classificationDef_.
##### `Class Breaks`
_Class Breaks_ is used to classify numeric data based on a number of breaks and a statistical method. Features can also be normalized before being classified.
```javascript
{
*type: 'classes',
*field: '',
*method: 'equalInterval' | 'naturalBreaks' | 'quantile' | 'std',
*breakCount: 7,
normType: 'field' | 'log' | 'percent',
normField: '' // mandatory if normType === 'field'
}
*required
```
e.g. An example feature collection has a field called _field1_ ranging in value from 0 - 29.
Input:
```javascript
{
type: 'classes',
field: 'field1',
method: 'equalInterval',
breakCount: 5,
}
```
Output (array of class intervals):
```javascript
[ [0-5],
[6-11],
[12-17],
[18-23],
[24-29] ]
```
##### `Unique Value`
_Unique Value_ is used to classify data based on a unique field(s). The output is an array of objects for each unique value combination. Each object contains an instance count, and the classifying unqiue field names and values.
```javascript
{
*type: 'unique',
*fields: ['', '', ''] // up to three fields
}
*required
```
e.g. An example feature collection has unique fields called _employeeID_ and _customerID_.
Input:
```javascript
{
type: 'unique',
fields: ['employeeID', 'customerID']
}
```
Output (array of instance objects):
```javascript
[
{count: 3, employeeID: 'A', customerID: 'M'},
{count: 1, employeeID: 'A', customerID: 'N'},
{count: 1, employeeID: 'B', customerID: 'M'},
{count: 2, employeeID: 'B', customerID: 'N'},
{count: 2, employeeID: 'B', customerID: 'O'},
{count: 1, employeeID: 'C', customerID: 'O'},
]
```
## `winnow.prepareQuery`
Returns a function that can be applied directly to a feature collection object, an array of features, or a single feature. Useful when you want to pass a stream of features through a filter.
```javascript
const options = {
where: String,
geometry: Object,
spatialPredicate: String,
fields: Array,
aggregates: Array
}
const filter = winnow.prepareQuery(options)
filter(geojson)
// returns the set of feature that match the query
```
## `winnow.querySql`
Execute sql directly against the query engine.
- Replace any variables with ?
- Table name should always be replaced by ?
- Non-string values always be replaced by ?
```javascript
const statement = 'Select * from ? where Genus in ?'
const data = geojson
const genus = ['Quercus']
winnow.querySql(statement, [geojson, genus])
// returns all features that match the query
```
## `winnow.prepareSql`
Pass in a statement and return a filter than can be applied to a feature collection object, an array of features or a single feature. Variables work in the same way as `winnow.sql`
```javascript
const statement = 'Select Trunk_Diameter from ? where Trunk_Diameter > 100'
const filter = winnow.prepareSql(statement)
filter(geojson)
// returns all the features that match the query
```
## OBJECTID generation
When option `toEsri` is `true`, winnow will check that features have a unique-identifier field. This is field is flagged with the `idField` option. If not present, winnow will look for a field named `OBJECTID` and use it as the unique-identifier by default. If no `OBJECTID` is present, winnow creates one by generating a numeric hash of the feature. By default, winnow uses FarmHash for hashing. Some cloud deployments currently have trouble executing Farmhash (Heroku, 2020-09-30), so you can use native Javascript hashing as an alternative. Simply set the environment variable `OBJECTID_FEATURE_HASH=javascript`.
# Issues
Find a bug or want to request a new feature? Please let us know by submitting an [issue](https://github.com/FeatureServer/winnow/issues).
# Contributing
Esri welcomes contributions from anyone and everyone. Please see our [guidelines for contributing](https://github.com/Esri/contributing) and the [RELEASE.md](RELEASE.md) for a description of our release process.
# License
[Apache 2.0](LICENSE)
[npm-img]: https://img.shields.io/npm/v/winnow.svg?style=flat-square
[npm-url]: https://www.npmjs.com/package/winnow
[travis-img]: https://img.shields.io/travis/koopjs/winnow/master.svg?style=flat-square
[travis-url]: https://travis-ci.org/koopjs/winnow
[standard-img]: https://img.shields.io/badge/code%20style-standard-brightgreen.svg
[standard-url]: http://standardjs.com/
[greenkeeper-image]: https://badges.greenkeeper.io/koopjs/winnow.svg
[greenkeeper-url]: https://greenkeeper.io/