CODEWITHSUNDEEP
pythongeojsonaltair
oliverjwroberts
oliverjwroberts

Reputation: 78

GeoJson file not plotting correctly in Altair

I am trying to create a visualisation in Altair that overlays major rivers onto a map of Europe, and some of the surrounding countries. I used this website to download a custom GeoJSON file of Europe, Asia and Africa. I then managed to successfully plot the base map using GeoPandas (imported as gpd) in the following code:

custom_world = gpd.read_file('customgeo.json')

base = alt.Chart(custom_world).mark_geoshape(color='lightgrey').encode(   
tooltip=[alt.Tooltip('name:N', title='Country')]
).properties(
    width=600,
    height=400
).project(
    scale=400, translate=[100, 550]
)
base

This is the output visualisation of JUST the map data

I am using major river GeoJSON data from this website; specifically this dataset. Now, when I attempt to plot this, Altair returns a somewhat correct output, as some of the rivers are plotted as expected, but the map is littered with obscure polygons.

majorrivers = gpd.read_file('major-rivers.geojson')

rivers = alt.Chart(majorrivers).mark_geoshape(
filled=False,
strokeWidth=2
).properties(
    width=600,
    height=400,
    title = 'Waterways'
).project(
    scale=400, translate=[100, 550]
)
base + rivers

As you can see from the output, something isn't quite right

It might be worth noting that the problem still persists even when I don't layer the chart and just plot 'rivers'. After numerous Google searches, I still find myself at a loss, so any help would be very much appreciated!

Upvotes: 1

Views: 434

Answers (1)

oliverjwroberts
oliverjwroberts

Reputation: 78

I'm answering my own question as I seemed to have fixed it, and want to share in case someone comes across this issue too.

It might have been important to note that I am using a Jupyter Notebook to create this visualisation. I just so happened to open another Notebook with a known working Altair visualisation and found the same obscure polygons present. To fix it, I closed JupyterLab, opened it back up and ran all cells in the Notebook.

Using the same code, this seemed to produce the desired output.

Upvotes: 1

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