Calculating correct area for polygons with geopandas

Question

I recently tried to calculate country sizes with geopandas and the included world file; and I am not capable to calculate the correct size for the chosen countries. Maybe someone can give me a hint where I made a mistake?

Tried various shapefiles (and the included world file shipped with geopandas); all of the afaik in epsg:4326

world = gpd.read_file(gpd.datasets.get_path('naturalearth_lowres'))
cnames = ['Austria','Sweden','Kenya']
epsgs = ['3857','3395']

for c in cnames:
    carea = world[world['name'] == c]
    for e in epsgs:
        carea = carea.to_crs(epsg=e)
        area = int(pd.to_numeric(carea['geometry'].area)/10**6)
        print(area)

Expected results are:

• Austria: 83,879 km²
• Sweden: 450,295 km²
• Kenya: 580,367 km²

Actual results I get:

• Austria: 187163
• Austria: 186592
• Sweden: 2190160
• Sweden: 2187138
• Kenya: 595731
• Kenya: 591749

So Kenya is quite close (also to the equator)? Is the reprojection not right?

Uncommunicative

Answer 1

To get correct area, you must use 'equal-area' projection. The one that works well with your code is epsg 6933. It is cylindrical equal-area projection.

Arce

Thanks, this clarifies a lot. In this question they talk about 3395 being an equal area crs: gis.stackexchange.com/questions/218450/… one of the reasons I was not on the right path :) – Uncommunicative