CODEWITHSUNDEEP
pythonshapelycartopy
Appolinaire Derbetini
Appolinaire Derbetini

Reputation: 61

Python (Cartopy): how to solve 'Polygon object error'

I am having this error when running a script. There is a way to correct it?

Thanks in advance

File "/usr/local/lib/python3.8/dist-packages/cartopy/mpl/geoaxes.py", line 718, in add_geometries
    feature = cartopy.feature.ShapelyFeature(geoms, crs, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/cartopy/feature/__init__.py", line 221, in __init__
    self._geoms = tuple(geometries)
TypeError: 'Polygon' object is not iterable

Here some python packages installed

Cartopy==0.18.0
Shapely==1.7.1
matplotlib==3.1.2
scipy==1.3.3
seaborn==0.9.0






def area(ax, iso, clr) :
    shp = shpreader.natural_earth(resolution='10m',category='cultural',
                                  name='admin_0_countries')
    reader = shpreader.Reader(shp)
    for n in reader.records() :
        if n.attributes['ADM0_A3'] == iso: 
            ax.add_geometries(n.geometry, ccrs.PlateCarree(), facecolor=clr, 
                              alpha = 1.00, linewidth =0.15, edgecolor = "black",
                              label=n.attributes['ADM0_A3']) 
    return ax

iso3 = ['CMR']

Upvotes: 2

Views: 1744

Answers (2)

wagnifico
wagnifico

Reputation: 732

The method add_geometries takes a collection of shapes as input. From the documentation:

add_geometries(geoms, crs, **kwargs)[source]

Add the given shapely geometries (in the given crs) to the axes. Parameters:

  • geoms – A collection of shapely geometries.
  • crs – The cartopy CRS in which the provided geometries are defined.

When plotting a single country you need to provide an iterable (a list) with a single item (the country you want to plot) for it to work:

ax.add_geometries(
    [n.geometry], ccrs.PlateCarree(), facecolor=clr, 
    alpha=1.00, linewidth=0.15, edgecolor="black",
    label=n.attributes['ADM0_A3'])

Upvotes: 1

Ashish Jain
Ashish Jain

Reputation: 467

Instead of these lines:

if n.attributes['ADM0_A3'] == iso: 
  ax.add_geometries(n.geometry, ccrs.PlateCarree(), facecolor=clr, alpha = 1.00, linewidth =0.15, edgecolor = "black", label=n.attributes['ADM0_A3'])

Put these lines. Here we have added exception handling and then tried to convert 'Polygon' objects into 'MultiPolygon' objects that do not give error:

try:
  ax.add_geometries(n.geometry, ccrs.PlateCarree(), facecolor=clr, alpha = 1.00, linewidth =0.15, edgecolor = "black", label=n.attributes['ADM0_A3']) 
except Exception as e:
  #print(e)
  import shapely.wkt as wkt
  from shapely.geometry import MultiPolygon
  list_str_polygons = [str(n.geometry)]
  c = MultiPolygon(map(wkt.loads, list_str_polygons))
  ax.add_geometries(c, ccrs.PlateCarree(), facecolor=clr, alpha = 1.00, linewidth =0.15, edgecolor = "black", label=n.attributes['ADM0_A3'])

Upvotes: 2

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