<!-- docs-type: how-to-guides https://diataxis.fr/how-to-guides/ -->

# How to use OFDS data

This page provides [examples](#examples) that demonstrate how to use OFDS data in common tools and [how-to guides](#how-to-guides) for specific topics.

## Examples

### Leaflet

The [Leaflet example](leaflet.ipynb) shows how to use Python, Leaflet and Folium to visualise OFDS JSON data.

### QGIS

The [OFDS QGIS plugin](https://github.com/Open-Telecoms-Data/ofds-qgis-plugin) provides support for importing OFDS JSON data into [QGIS](https://qgis.org/):

1. [Install QGIS](https://qgis.org/resources/installation-guide/)
1. [Install the OFDS QGIS plugin](https://github.com/Open-Telecoms-Data/ofds-qgis-plugin?tab=readme-ov-file#installation)
1. Download the [example OFDS JSON file](../../../examples/json/network-package.json)
1. [Create a new project in QGIS and add OFDS layers](https://github.com/Open-Telecoms-Data/ofds-qgis-plugin?tab=readme-ov-file#1-initial-project-setup)
1. [Import](https://github.com/Open-Telecoms-Data/ofds-qgis-plugin?tab=readme-ov-file#workflow-b-edit-an-existing-ofds-dataset) the example OFDS JSON file
1. Explore the [attribute table](https://docs.qgis.org/3.22/en/docs/user_manual/working_with_vector/attribute_table.html) for the nodes and spans layers and use the [GeoPackage reference](../../reference/data_formats/geopackage/index.md) to understand the layer structure and the meaning of the attributes.

## How to guides

### How to plot coordinates accurately

Coordinates in OFDS data are specified in the `urn:ogc:def:crs:OGC::CRS84` [coordinate reference system](../../reference/crs.md) (CRS). To create accurate maps, you need need to set the correct coordinate reference system when using OFDS data.

You also need to pay careful attention to coordinate ordering. `urn:ogc:def:crs:OGC::CRS84` is equivalent to EPSG:4326 with reversed axes so, if it is not supported by the tool that you are using, you can set your CRS to EPSG:4326 and ensure that you read coordinates in longitude, latitude order.

For more information on transforming coordinates from one CRS to another, see [how to transform coordinates to the correct coordinate reference system](../publication.md#how-to-transform-coordinates-to-the-correct-coordinate-reference-system).

```{eval-rst}
.. toctree::
   :hidden:

   leaflet
```