Departements

http://geopandas.org/gallery/plotting_basemap_background.html#adding-a-background-map-to-plots

https://www.data.gouv.fr/fr/datasets/contours-des-departements-francais-issus-d-openstreetmap/



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!wget http://osm13.openstreetmap.fr/~cquest/openfla/export/departements-20140306-100m-shp.zip



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!unzip -u departements-20140306-100m-shp.zip



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import geopandas



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df = geopandas.read_file("departements-20140306-100m.shp")
#df = df.iloc[[78, 91, 92, 94]]                 # OK
#df = df.loc[df.code_insee == "78"]             # OK
df = df.loc[df.code_insee.isin(["78", "91"])]   # OK



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df



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ax = df.plot(figsize=(10, 10), alpha=0.5, edgecolor='k')



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#df.to_file("departements_orig.geojson", driver="GeoJSON")

Convert the data to Web Mercator



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df2 = df.to_crs(epsg=3857)



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df2



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ax = df.plot(figsize=(10, 10), alpha=0.5, edgecolor='k')

Contextily helper function



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import contextily as ctx

def add_basemap(ax, zoom, url='http://tile.stamen.com/terrain/tileZ/tileX/tileY.png'):
    xmin, xmax, ymin, ymax = ax.axis()
    basemap, extent = ctx.bounds2img(xmin, ymin, xmax, ymax, zoom=zoom, url=url)
    ax.imshow(basemap, extent=extent, interpolation='bilinear')
    # restore original x/y limits
    ax.axis((xmin, xmax, ymin, ymax))

Add background tiles to plot



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ax = df2.plot(figsize=(10, 10), alpha=0.5, edgecolor='k')
add_basemap(ax, zoom=11, url=ctx.sources.ST_TONER_LITE)
ax.set_axis_off()

Save selected departments into a GeoJSON file



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import fiona
fiona.supported_drivers



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df.to_file("departements.geojson", driver="GeoJSON")



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df = geopandas.read_file("departements.geojson")



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df



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ax = df.plot(figsize=(10, 10), alpha=0.5, edgecolor='k')