CODEWITHSUNDEEP
pythontopojsonjupyter-labaltairgeomap
ilyas
ilyas

Reputation: 629

How to create a TopoJSON geomap using Altair library for Python?

I am trying to create a geomap of a state using Altair package for Python. I will then plot let's say dots representing some event at a location specified by its latitude & longitude. I follow the Altair's example gallery here. The TopoJSON file is located in the GitHub repository deldersveld/topojson. However, I can't get it to draw the map of Michigan. Is this file missing something? Anyone who can help me?

Environment:

Upvotes: 0

Views: 954

Answers (1)

jakevdp
jakevdp

Reputation: 86320

You can do something like this:

import altair as alt

url = "https://raw.githubusercontent.com/deldersveld/topojson/master/countries/us-states/MI-26-michigan-counties.json"

source = alt.topo_feature(url, "cb_2015_michigan_county_20m")

alt.Chart(source).mark_geoshape().encode(
    tooltip='properties.NAME:N'
)

enter image description here

The key is to look in the "objects" and "properties" entries of the TopoJSON file to figure out what to use for features and encodings.

Upvotes: 3

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