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https://github.com/captchanjack/osmdata
Go library for downloading OpenStreetMap data using the Overpass and Nominatim API
https://github.com/captchanjack/osmdata
Last synced: 2 days ago
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Go library for downloading OpenStreetMap data using the Overpass and Nominatim API
- Host: GitHub
- URL: https://github.com/captchanjack/osmdata
- Owner: captchanjack
- License: mit
- Created: 2022-11-15T11:05:11.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2022-11-20T14:04:38.000Z (almost 2 years ago)
- Last Synced: 2024-06-21T11:02:35.719Z (5 months ago)
- Language: Go
- Size: 18.6 KB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# osmdata
This is a Go library for downloading OpenStreetMap data using the [Overpass](https://overpass-turbo.eu/) and [Nominatim](https://nominatim.openstreetmap.org/ui/search.html) API.
## Core Features
- Building and executing preset queries against road, rail, walk or bicycle networks, with the flexibility of querying against a polygon, bounding box, radius, or a place name (as free-text)
- Supports XML, JSON and CSV data format and exporting to disk
- Building Overpass queries dynamically with `Statement` structs
- Executing raw Overpass string queries
- Searching the Nominatim API for polygons using free-text
## Usage
### Raw String Queries
Let's start with an simple Overpass query that retrieves all traffic light nodes in an 500m radius area somewhere in Melbourne, Australia:
```
import ovp "github.com/captchanjack/osmdata/overpass"
queryStr := "[out:json];node[\"highway\"=\"traffic_signals\"](around:500.0,-37.740347,144.930127);out body;"
resp, err := ovp.OverpassQuery(queryStr)
```
`resp` can be unmarshalled and should look something like this:
```
{
"version": 0.6,
"generator": "Overpass API 0.7.59 e21c39fe",
"osm3s": {
"timestamp_osm_base": "2022-11-15T12:23:09Z",
"copyright": "The data included in this document is from www.openstreetmap.org. The data is made available under ODbL."
},
"elements": [
{
"type": "node",
"id": 68717542,
"lat": -37.7435041,
"lon": 144.9282267,
"tags": {
"highway": "traffic_signals"
}
},
{
"type": "node",
"id": 5547839707,
"lat": -37.7410101,
"lon": 144.9318164,
"tags": {
"highway": "traffic_signals",
"traffic_signals": "ramp_meter",
"traffic_signals:direction": "forward"
}
}
]
}
```
### Preset Queries
Mentioned earlier, this library offers a few useful preset queries against various network types and allows the parameterisation of spatial filters. This example shows how to query all nodes, ways and relations on a road network in Melbourne City, Austrlia:
```
import (
"fmt"
osm "github.com/captchanjack/osmdata"
ovp "github.com/captchanjack/osmdata/overpass"
)
query := osm.GetPresetQuery(
osm.PlaceName, // Query method, i.e.. BoundingBox, Radius, Polygon, PlaceName
osm.Drive, // Preset network type, i.e. Drive, Walk, Bicycle, Rail, etc.
true, // Whether to download metadata i.e. changeset ids etc.
ovp.JSON, // Output format, supports XML, JSON and CSV
"Melbourne City, Australia" // Argument(s) specific to the query method, in this case the free-text describing the place name
)
fmt.Println(query.GetCompiled()) // Print the query
resp, err := query.Execute() // Execute the query
```
### Building Queries
We can build queryies dynamically using `Statement` structs, let's try replicate the raw string query example from earlier:
```
import (
"fmt"
ovp "github.com/captchanjack/osmdata/overpass"
)
// Settings statement, output JSON format
// [out:json];
settingsStmt := ovp.NewSettingsStatement(*ovp.NewSetting(ovp.Out, ovp.JSON))
// Main block statement, filtering nodes that within a certain radius and are traffic signals
// node[\"highway\"=\"traffic_signals\"](around:500.0,-37.740347,144.930127);
tagFilters := []ovp.TagFilter{*ovp.NewTagFilter(ovp.Equals, "highway", "traffic_signals")}
elementFilters := ovp.NewElementFilter(ovp.AroundFilter, 500.0, [][]float64{{-37.740347, 144.930127})
nodeStmt := ovp.NewElementStatement(ovp.Node, tagFilters, elementFilters)
// Output statement, exporting the body data
// out body;
bodyStmt := ovp.NewOutStatement(ovp.Body)
// Finally we add all the statements into a stack
stackStmt := ovp.NewStackStatement(settingsStmt, nodeStmt, bodyStmt)
// We can inspect the query and execute it
fmt.Println(stackStmt.GetCompiled())
resp, err := stackStmt.Execute()
```
### Exporting
We can export the downloaded data to a file on disk:
```
import (
"fmt"
osm "github.com/captchanjack/osmdata"
ovp "github.com/captchanjack/osmdata/overpass"
)
query := osm.GetPresetQuery(
osm.PlaceName, // Query method, i.e.. BoundingBox, Radius, Polygon, PlaceName
osm.Drive, // Preset network type, i.e. Drive, Walk, Bicycle, Rail, etc.
true, // Whether to download metadata i.e. changeset ids etc.
ovp.JSON, // Output format, supports XML, JSON and CSV
"Melbourne City, Australia" // Argument(s) specific to the query method, in this case the free-text describing the place name
)
resp, err := query.ExecuteAndExport("./test.json") // Execute the query and export
```