TopoJoin

A lightweight utility to join CSV data to a topojson file. Produces a new topojson file with CSV properties added to the properties of each feature.

• Free software: MIT
• Documentation: https://topojoin.readthedocs.io.

Install

pip install topojoin

Basic usage

Command line

In the command line, enter the topojoin command followed by the path to your topojson file and your CSV file.

By default TopoJoin will assume both files have a common field called 'id' that can be joined.

topojoin example.json example.csv

>> Joining example.csv to example.json...
>> CSV key 'id' will be joined with topojson key 'id'
>> Joined data saved to: joined.json

To define the join keys, use the '-tk' option for the key in your topojson file and the '-ck' option for the key in your CSV file:

topojoin -tk GEOID -ck fips example.json example.csv

>> Joining example.csv to example.json...
>> CSV key 'fips' will be joined with topojson key 'GEOID'
>> Joined data saved to: joined.json

Programmatic

If you prefer, you can also import and call TopoJoin from a python script:

from topojoin.topojoin import TopoJoin

tj = TopoJoin("./example.json", "./example.csv", topo_key="GEOID", csv_key="fips")
topojson_data = tj.join()

Or, to write to a file:

from topojoin.topojoin import TopoJoin

tj = TopoJoin("./example.json", "./example.csv", topo_key="GEOID", csv_key="fips")
tj.join("joined.json")

Advanced usage

Command line

TopoJoin's actions can be modified in a number of ways by passing optional arguments. Here are its available options:

-tk, --topokey TEXT
	Key in CSV file that will be used to join with CSV file [default: id]
-ck, --csvkey TEXT
	Key in CSV file that will be used to join with topojson file [default: id]
-cp, --csv_props TEXT
	Comma separated list of fields in CSV file to merge to each topojson feature (eg: name,population,net_income). Defaults to including all fields in CSV file.
-o, --output_path TEXT
	Output path of joined topojson file. Defaults to current working directory.
-q, --quiet	Disables stdout during program run
--version	Show the version and exit.
--help	Show this message and exit.

For example:

topojoin -tk GEOID -ck fips -o "mydir/my-custom-filename.json" example.json example.csv

TO DO

• Prefix CSV keys if key name is already present in topojson props.
• Raise exception or prompt if CSV file has duplicate values in column specified by csv_key.

Alternatives

• py-geojoin