make_data_extract

make_data_extract.py¶

The make_data_extract.py program is used to extract OpenStreetMap (OSM) data for use with the select_one_from_file function in ODK Collect. This function allows users to select from a list of options generated from an external file. The make_data_extract.py program creates a data extract that can be used as an external file with the XLSForm. The data extract can be created using local Postgres database, or the remote Underpass database.

To use the new select_one_from_file for editing existing OSM data you need to produce a data extract from OSM. This can be done several ways, but needed to be automated to be used for FMTM.

options:
 --help (-h)               show this help message and exit
 --verbose (-v)            verbose output
 --geojson (-g) GEOJSON    Name of the GeoJson output file
 --boundary (-b) BOUNDARY  Boundary polygon to limit the data size
 --category (-c) CATEGORY  Which category to extract
 --uri (-u) URI            Database URI
 --xlsfile (-x) XLSFILE    An XLSForm in the library
 --list (-l) List          List all XLSForms in the library

Examples¶

Make*data*extract uses a Postgres database to extract OSM data. By default, the program uses localhost as the database host. If you use *underpassas the data base name, this will remotely access the Humanitarian OpenStreetMap Team(HOT) maintained OSM database that covers the entire planet, and is updated every minute. The name of the database can be specified using the *--uri** option. The program extracts the buildings category of OSM data by default. The size of the extracted data can be limited using the _--boundary* option. The program outputs the data in GeoJSON format.

For raw OSM data, the existing country data is downloaded from GeoFabrik, and imported using a modified schema for osm2pgsql. First create the database and install two postgres extensions:

# createdb nigeria
psql -d nigeria -c "CREATE EXTENSION postgis"
psql -d nigeria -c "CREATE EXTENSION hstore"

And then import the OSM data.

osm2pgsql --create -d nigeria --extra-attributes --output=flex --style raw.lua nigeria-latest-internal.osm.pbf

The raw.lua script is available here. It's part of the Underpass project. It uses a more compressed and efficient data schema.

Example¶

./make_data_extract.py -u colorado --boundary mycounty.geojson -g mycounty_buildings.geojson

This example extracts the buildings category of OSM data from a Postgres database named colorado. The program limits the size of the extracted data to the boundary specified in the mycounty.geojson file. The program outputs the data in GeoJSON format to a file named mycounty_buildings.geojson.

Boundary¶

The --boundary option can be used to specify a polygon boundary to limit the size of the extracted data. The boundary has to be in GeoJSON format, both multipolygons and polygons are supported.

Example:

./make_data_extract.py -u foo@colorado --category healthcare --boundary mycounty.geojson -g mycounty_healthcare.geojson

This example extracts the healthcare category of OSM data from a Postgres database named colorado with e user foo. The program limits the size of the extracted data to the boundary specified in the mycounty.geojson file. The program outputs the data in GeoJSON format to a file named mycounty_healtcare.geojson.

Category¶

The --category option can be used to specify which category of OSM data to extract. The program supports any category in the xlsform library

Example¶

./make_data_extract.py -u underpass --boundary mycounty.geojson --category amenities -g mycounty_amenities.geojson

This example uses Overpass Turbo to extract the amenities category of OSM data within the boundary specified in the mycounty.geojson file. The program outputs the data in GeoJSON format to a file named mycounty_amenities.geojson.

Output File Format¶

The program outputs the extracted OSM data in GeoJSON format. The name of the output file can be specified using the --geojson option. If the option is not specified, the program uses the input file name with _buildings.geojson appended to it.

./make_data_extract.py -u colorado --boundary mycounty.geojson -g mycounty_buildings.geojson

File Formats¶

ODK has 3 file formats. The primary one is the source file, which is in XLSX format, and follows the XLSXForm specification. This file is edited using a spreadsheet program, and convert using the xls2xform program. That conversion products an ODK XML file. That file is used by ODK Collect to create the input forms for the mobile app. When using ODK Collect, the output file is another XML format, unique to ODK Collect. These are the data collection instances.

The ODK server, ODK Central supports the downloading of XForms to the mobile app, and also supports downloading the collected data. The only output format is CSV.