“‘Polygon”对象不可迭代- iPython Cookbook
“‘Polygon”对象不可迭代- iPython Cookbook
提问于 2020-12-03 18:34:10
我正在学习使用Cartopy在python中实现数据可视化。
我有这个代码来绘制非洲的人口和国内生产总值。
def choropleth(ax, attr, cmap_name):
# We need to normalize the values before we can
# use the colormap.
values = [c.attributes[attr] for c in africa]
norm = Normalize(
vmin=min(values), vmax=max(values))
cmap = plt.cm.get_cmap(cmap_name)
for c in africa:
v = c.attributes[attr]
sp = ShapelyFeature(c.geometry, crs,
edgecolor='k',
facecolor=cmap(norm(v)))
ax.add_feature(sp)
fig, (ax1, ax2) = plt.subplots(
1, 2, figsize=(10, 16),
subplot_kw=dict(projection=crs))
draw_africa(ax1)
choropleth(ax1, 'POP_EST', 'Reds')
ax1.set_title('Population')
draw_africa(ax2)
choropleth(ax2, 'GDP_MD_EST', 'Blues')
ax2.set_title('GDP')并且预期的输出应该是-
但我得到了一个错误-
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-41-b443c58ecbd5> in <module>
3 subplot_kw=dict(projection=crs))
4 draw_africa(ax1)
----> 5 choropleth(ax1, 'POP_EST', 'Reds')
6 ax1.set_title('Population')
7
<ipython-input-40-161126226479> in choropleth(ax, attr, cmap_name)
8 for c in africa:
9 v = c.attributes[attr]
---> 10 sp = ShapelyFeature(c.geometry, crs,
11 edgecolor='k',
12 facecolor=cmap(norm(v)))
~/anaconda3/lib/python3.8/site-packages/cartopy/feature/__init__.py in __init__(self, geometries, crs, **kwargs)
219 """
220 super(ShapelyFeature, self).__init__(crs, **kwargs)
--> 221 self._geoms = tuple(geometries)
222
223 def geometries(self):
TypeError: 'Polygon' object is not iterable我试着在github上搜索这个问题，但是没有用。有人能帮我解决这个问题吗?我该怎么纠正呢？
这是供参考的site。
回答 1
Stack Overflow用户
回答已采纳
发布于 2020-12-03 20:49:48
问题是代码试图将一个整形的Polygon传递给一个需要MultiPolygon的函数。swatchai在这里https://stackoverflow.com/a/63812490/13208790的一个优雅的解决方案是捕获Polygons并将它们放在一个列表中，这样它们就可以被视为MultiPolygons。
以下是根据您的情况调整的代码：
for i, c in enumerate(africa):
v = c.attributes[attr]
print(i)
# swatchai's Polygon catch logic
if c.geometry.geom_type=='MultiPolygon':
# this is a list of geometries
sp = ShapelyFeature(c.geometry, crs,
edgecolor='k',
facecolor=cmap(norm(v)))
elif c.geometry.geom_type=='Polygon':
# this is a single geometry
sp = ShapelyFeature([c.geometry], crs,
edgecolor='k',
facecolor=cmap(norm(v)))
else:
pass #do not plot the geometry页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/65124253
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