为什么 matplotlib basemap 没有绘制地图中某些区域的颜色？
Why is matplotlib basemap not plotting the colours of some areas in my map?
下面的代码应该为越南的所有州着色：
import pandas as pd
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
fig, ax = plt.subplots(figsize=(10,20))
# create the map
map = Basemap(resolution='l', # c, l, i, h, f or None
projection='merc',
lat_0=15.95, lon_0=105.85,
llcrnrlon=102., llcrnrlat= 8.31, urcrnrlon=109.69, urcrnrlat=23.61)
# load the shapefile, use the name 'states'
map.readshapefile(r'path\to\gadm36_VNM_1', name='states', drawbounds=True)
# shapefile downloaded from http://www.gadm.org/
# collect the state names from the shapefile attributes so we can
# look up the shape obect for a state by it's name
state_names = []
for shape_dict in map.states_info:
state_names.append(shape_dict['VARNAME_1'])
ax = plt.gca() # get current axes instance
# NOR, CEN, SOU and MEK are some subdivisions I have created for the states of Vietnam
NOR = ['Lai Chau',
'Lao Cai',
'Ha Giang',
'Cao Bang',
'Dien Bien',
'Son La',
'Yen Bai',
'Tuyen Quang',
'Bac Kan',
'Lang Son',
'Thai Nguyen',
'Phu Tho',
'Vinh Phuc',
'Hoa Binh',
'Ha Noi',
'Bac Ninh',
'Hai Duong',
'Hung Yen',
'Ha Nam',
'Quang Ninh',
'Hai Phong',
'Thai Binh',
'Nam Dinh',
'Bac Giang',
'Ninh Binh']
CEN = ['Thanh Hoa',
'Nghe An',
'Ha Tinh',
'Quang Binh',
'Quang Tri',
'Thua Thien Hue',
'Da Nang']
SOU = ['Quang Nam',
'Kon Tum',
'Quang Ngai',
'Gia Lai',
'Binh Dinh',
'Dak Lak',
'Phu Yen',
'Khanh Hoa',
'Dak Nong',
'Lam Dong',
'Ninh Thuan']
MEK = ['Binh Phuoc',
'Dong Nai',
'Binh Thuan',
'Tay Ninh',
'Binh Duong',
'Dong Nai',
'Ba Ria - Vung Tau',
'Ho Chi Minh',
'Long An',
'An Giang',
'Dong Thap',
'Tien Giang',
'Kien Giang',
'Can Tho',
'Vinh Long',
'Ben Tre',
'Hau Giang',
'Tra Vinh',
'Soc Trang',
'Bac Lieu',
'Ca Mau']
# Define the colours to be used to colour the states
from matplotlib import cm
from numpy import linspace
start = 0.5
stop = 1.0
number_of_lines= 4
cm_subsection = linspace(start, stop, number_of_lines)
cm_subsection[0] = cm_subsection[0]*4
cm_subsection[1] = cm_subsection[1]*0.6
cm_subsection[2] = cm_subsection[2]*0.8
cm_subsection[3] = cm_subsection[3]*0.1
colors = [ cm.Blues(x) for x in cm_subsection ]
for state in NOR:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[0], edgecolor=colors[0])
ax.add_patch(poly)
for state in CEN:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[1], edgecolor=colors[1])
ax.add_patch(poly)
for state in SOU:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[2], edgecolor=colors[2])
ax.add_patch(poly)
for state in MEK:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[3], edgecolor=colors[3])
ax.add_patch(poly)
import matplotlib.patches as mpatches
NOR_patch = mpatches.Patch(color=colors[0], label='Rate: 34.85%')
CEN_patch = mpatches.Patch(color=colors[1], label='Rate: 25.61%')
SOU_patch = mpatches.Patch(color=colors[2], label='Rate: 32.66%')
MEK_patch = mpatches.Patch(color=colors[3], label='Rate: 20.02%')
plt.legend(handles=[NOR_patch, CEN_patch, SOU_patch, MEK_patch])
plt.show()
但这会生成下面的地图，其中一些州没有着色，即使它们出现在州名和分区中：
事实上，如果我尝试为名称不在列表中的州着色，它会抛出错误：
MEK.append('ABCDE')
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-619-a89da62a0831> in <module>()
134
135 for state in MEK:
--> 136 seg = map.states[state_names.index(state)]
137 poly = Polygon(seg, facecolor=colors[3], edgecolor=colors[3])
138 ax.add_patch(poly)
ValueError: 'ABCDE' is not in list
所以，很明显，没有颜色的状态出现在列表中，因为我没有收到任何错误。那么，这是怎么回事？
编辑： 令我震惊的是，几乎所有没有颜色的州都至少与现实世界中的 sea/ocean 共享其边界的某些部分。 6 个例外在下面以红色突出显示：
这很有趣！它与这个问题有什么关系吗？如果是，什么？为什么？为什么存在这 6 个例外？
编辑 2： 我在绘制菲律宾地图时得到类似的结果：
在shapefiles中，一个country/province/whatever，可能会被分解成几条线段。为什么会这样，我不知道，但为了正确绘制形状，您需要使用所有必要的线段。实际上，在 Basemap documentation for shapefiles 中有一个在 'filling polygons' 下的例子，如何正确地做到这一点。我将他们的示例改编为您的用例。它可能不是最佳解决方案，但它似乎有效。
import pandas as pd
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
from matplotlib import patches as mpatches
from matplotlib import cm
from numpy import linspace
import matplotlib.patches as mpatches
from matplotlib.collections import PatchCollection
fig, ax = plt.subplots(figsize=(4,8))
# create the map
map = Basemap(resolution='l', # c, l, i, h, f or None
projection='merc',
lat_0=15.95, lon_0=105.85,
llcrnrlon=102., llcrnrlat= 8.31, urcrnrlon=109.69, urcrnrlat=23.61)
# load the shapefile, use the name 'states'
map.readshapefile(r'shapefiles/gadm36_VNM_1', name='states', drawbounds=True)
# shapefile downloaded from http://www.gadm.org/
# collect the state names from the shapefile attributes so we can
# look up the shape obect for a state by it's name
state_names = []
for shape_dict in map.states_info:
state_names.append(shape_dict['VARNAME_1'])
ax = plt.gca() # get current axes instance
# NOR, CEN, SOU and MEK are some subdivisions I have created for the states of Vietnam
NOR = ['Lai Chau',
'Lao Cai',
'Ha Giang',
'Cao Bang',
'Dien Bien',
'Son La',
'Yen Bai',
'Tuyen Quang',
'Bac Kan',
'Lang Son',
'Thai Nguyen',
'Phu Tho',
'Vinh Phuc',
'Hoa Binh',
'Ha Noi',
'Bac Ninh',
'Hai Duong',
'Hung Yen',
'Ha Nam',
'Quang Ninh',
'Hai Phong',
'Thai Binh',
'Nam Dinh',
'Bac Giang',
'Ninh Binh']
CEN = ['Thanh Hoa',
'Nghe An',
'Ha Tinh',
'Quang Binh',
'Quang Tri',
'Thua Thien Hue',
'Da Nang']
SOU = ['Quang Nam',
'Kon Tum',
'Quang Ngai',
'Gia Lai',
'Binh Dinh',
'Dak Lak',
'Phu Yen',
'Khanh Hoa',
'Dak Nong',
'Lam Dong',
'Ninh Thuan']
MEK = ['Binh Phuoc',
'Dong Nai',
'Binh Thuan',
'Tay Ninh',
'Binh Duong',
'Dong Nai',
'Ba Ria - Vung Tau',
'Ho Chi Minh',
'Long An',
'An Giang',
'Dong Thap',
'Tien Giang',
'Kien Giang',
'Can Tho',
'Vinh Long',
'Ben Tre',
'Hau Giang',
'Tra Vinh',
'Soc Trang',
'Bac Lieu',
'Ca Mau']
# Define the colours to be used to colour the states
start = 0.5
stop = 1.0
number_of_lines= 4
cm_subsection = linspace(start, stop, number_of_lines)
cm_subsection[0] = cm_subsection[0]*4
cm_subsection[1] = cm_subsection[1]*0.6
cm_subsection[2] = cm_subsection[2]*0.8
cm_subsection[3] = cm_subsection[3]*0.1
colors = [ cm.Blues(x) for x in cm_subsection ]
##collecting the line segments for the provinces:
patches = {state: [] for state in NOR+CEN+SOU+MEK}
for info, shape in zip(map.states_info, map.states):
for state in NOR+CEN+SOU+MEK:
if info['VARNAME_1'] == state:
patches[state].append(mpatches.Polygon(
shape, True,
))
##coloring the the provinces by group:
for state in NOR:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[0], edgecolor=colors[0]
))
for state in CEN:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[1], edgecolor=colors[1]
))
for state in SOU:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[2], edgecolor=colors[2]
))
for state in MEK:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[3], edgecolor=colors[3]
))
NOR_patch = mpatches.Patch(color=colors[0], label='Rate: 34.85%')
CEN_patch = mpatches.Patch(color=colors[1], label='Rate: 25.61%')
SOU_patch = mpatches.Patch(color=colors[2], label='Rate: 32.66%')
MEK_patch = mpatches.Patch(color=colors[3], label='Rate: 20.02%')
plt.legend(handles=[NOR_patch, CEN_patch, SOU_patch, MEK_patch])
plt.show()
结果符合预期：
请注意，我只能在 Python 3.6 下测试代码，因此可能需要进行一些调整。希望这有帮助。
下面的代码应该为越南的所有州着色：
import pandas as pd
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
fig, ax = plt.subplots(figsize=(10,20))
# create the map
map = Basemap(resolution='l', # c, l, i, h, f or None
projection='merc',
lat_0=15.95, lon_0=105.85,
llcrnrlon=102., llcrnrlat= 8.31, urcrnrlon=109.69, urcrnrlat=23.61)
# load the shapefile, use the name 'states'
map.readshapefile(r'path\to\gadm36_VNM_1', name='states', drawbounds=True)
# shapefile downloaded from http://www.gadm.org/
# collect the state names from the shapefile attributes so we can
# look up the shape obect for a state by it's name
state_names = []
for shape_dict in map.states_info:
state_names.append(shape_dict['VARNAME_1'])
ax = plt.gca() # get current axes instance
# NOR, CEN, SOU and MEK are some subdivisions I have created for the states of Vietnam
NOR = ['Lai Chau',
'Lao Cai',
'Ha Giang',
'Cao Bang',
'Dien Bien',
'Son La',
'Yen Bai',
'Tuyen Quang',
'Bac Kan',
'Lang Son',
'Thai Nguyen',
'Phu Tho',
'Vinh Phuc',
'Hoa Binh',
'Ha Noi',
'Bac Ninh',
'Hai Duong',
'Hung Yen',
'Ha Nam',
'Quang Ninh',
'Hai Phong',
'Thai Binh',
'Nam Dinh',
'Bac Giang',
'Ninh Binh']
CEN = ['Thanh Hoa',
'Nghe An',
'Ha Tinh',
'Quang Binh',
'Quang Tri',
'Thua Thien Hue',
'Da Nang']
SOU = ['Quang Nam',
'Kon Tum',
'Quang Ngai',
'Gia Lai',
'Binh Dinh',
'Dak Lak',
'Phu Yen',
'Khanh Hoa',
'Dak Nong',
'Lam Dong',
'Ninh Thuan']
MEK = ['Binh Phuoc',
'Dong Nai',
'Binh Thuan',
'Tay Ninh',
'Binh Duong',
'Dong Nai',
'Ba Ria - Vung Tau',
'Ho Chi Minh',
'Long An',
'An Giang',
'Dong Thap',
'Tien Giang',
'Kien Giang',
'Can Tho',
'Vinh Long',
'Ben Tre',
'Hau Giang',
'Tra Vinh',
'Soc Trang',
'Bac Lieu',
'Ca Mau']
# Define the colours to be used to colour the states
from matplotlib import cm
from numpy import linspace
start = 0.5
stop = 1.0
number_of_lines= 4
cm_subsection = linspace(start, stop, number_of_lines)
cm_subsection[0] = cm_subsection[0]*4
cm_subsection[1] = cm_subsection[1]*0.6
cm_subsection[2] = cm_subsection[2]*0.8
cm_subsection[3] = cm_subsection[3]*0.1
colors = [ cm.Blues(x) for x in cm_subsection ]
for state in NOR:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[0], edgecolor=colors[0])
ax.add_patch(poly)
for state in CEN:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[1], edgecolor=colors[1])
ax.add_patch(poly)
for state in SOU:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[2], edgecolor=colors[2])
ax.add_patch(poly)
for state in MEK:
seg = map.states[state_names.index(state)]
poly = Polygon(seg, facecolor=colors[3], edgecolor=colors[3])
ax.add_patch(poly)
import matplotlib.patches as mpatches
NOR_patch = mpatches.Patch(color=colors[0], label='Rate: 34.85%')
CEN_patch = mpatches.Patch(color=colors[1], label='Rate: 25.61%')
SOU_patch = mpatches.Patch(color=colors[2], label='Rate: 32.66%')
MEK_patch = mpatches.Patch(color=colors[3], label='Rate: 20.02%')
plt.legend(handles=[NOR_patch, CEN_patch, SOU_patch, MEK_patch])
plt.show()
但这会生成下面的地图，其中一些州没有着色，即使它们出现在州名和分区中：
事实上，如果我尝试为名称不在列表中的州着色，它会抛出错误：
MEK.append('ABCDE')
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-619-a89da62a0831> in <module>()
134
135 for state in MEK:
--> 136 seg = map.states[state_names.index(state)]
137 poly = Polygon(seg, facecolor=colors[3], edgecolor=colors[3])
138 ax.add_patch(poly)
ValueError: 'ABCDE' is not in list
所以，很明显，没有颜色的状态出现在列表中，因为我没有收到任何错误。那么，这是怎么回事？
编辑： 令我震惊的是，几乎所有没有颜色的州都至少与现实世界中的 sea/ocean 共享其边界的某些部分。 6 个例外在下面以红色突出显示：
这很有趣！它与这个问题有什么关系吗？如果是，什么？为什么？为什么存在这 6 个例外？
编辑 2： 我在绘制菲律宾地图时得到类似的结果：
在shapefiles中，一个country/province/whatever，可能会被分解成几条线段。为什么会这样，我不知道，但为了正确绘制形状，您需要使用所有必要的线段。实际上，在 Basemap documentation for shapefiles 中有一个在 'filling polygons' 下的例子，如何正确地做到这一点。我将他们的示例改编为您的用例。它可能不是最佳解决方案，但它似乎有效。
import pandas as pd
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
from matplotlib import patches as mpatches
from matplotlib import cm
from numpy import linspace
import matplotlib.patches as mpatches
from matplotlib.collections import PatchCollection
fig, ax = plt.subplots(figsize=(4,8))
# create the map
map = Basemap(resolution='l', # c, l, i, h, f or None
projection='merc',
lat_0=15.95, lon_0=105.85,
llcrnrlon=102., llcrnrlat= 8.31, urcrnrlon=109.69, urcrnrlat=23.61)
# load the shapefile, use the name 'states'
map.readshapefile(r'shapefiles/gadm36_VNM_1', name='states', drawbounds=True)
# shapefile downloaded from http://www.gadm.org/
# collect the state names from the shapefile attributes so we can
# look up the shape obect for a state by it's name
state_names = []
for shape_dict in map.states_info:
state_names.append(shape_dict['VARNAME_1'])
ax = plt.gca() # get current axes instance
# NOR, CEN, SOU and MEK are some subdivisions I have created for the states of Vietnam
NOR = ['Lai Chau',
'Lao Cai',
'Ha Giang',
'Cao Bang',
'Dien Bien',
'Son La',
'Yen Bai',
'Tuyen Quang',
'Bac Kan',
'Lang Son',
'Thai Nguyen',
'Phu Tho',
'Vinh Phuc',
'Hoa Binh',
'Ha Noi',
'Bac Ninh',
'Hai Duong',
'Hung Yen',
'Ha Nam',
'Quang Ninh',
'Hai Phong',
'Thai Binh',
'Nam Dinh',
'Bac Giang',
'Ninh Binh']
CEN = ['Thanh Hoa',
'Nghe An',
'Ha Tinh',
'Quang Binh',
'Quang Tri',
'Thua Thien Hue',
'Da Nang']
SOU = ['Quang Nam',
'Kon Tum',
'Quang Ngai',
'Gia Lai',
'Binh Dinh',
'Dak Lak',
'Phu Yen',
'Khanh Hoa',
'Dak Nong',
'Lam Dong',
'Ninh Thuan']
MEK = ['Binh Phuoc',
'Dong Nai',
'Binh Thuan',
'Tay Ninh',
'Binh Duong',
'Dong Nai',
'Ba Ria - Vung Tau',
'Ho Chi Minh',
'Long An',
'An Giang',
'Dong Thap',
'Tien Giang',
'Kien Giang',
'Can Tho',
'Vinh Long',
'Ben Tre',
'Hau Giang',
'Tra Vinh',
'Soc Trang',
'Bac Lieu',
'Ca Mau']
# Define the colours to be used to colour the states
start = 0.5
stop = 1.0
number_of_lines= 4
cm_subsection = linspace(start, stop, number_of_lines)
cm_subsection[0] = cm_subsection[0]*4
cm_subsection[1] = cm_subsection[1]*0.6
cm_subsection[2] = cm_subsection[2]*0.8
cm_subsection[3] = cm_subsection[3]*0.1
colors = [ cm.Blues(x) for x in cm_subsection ]
##collecting the line segments for the provinces:
patches = {state: [] for state in NOR+CEN+SOU+MEK}
for info, shape in zip(map.states_info, map.states):
for state in NOR+CEN+SOU+MEK:
if info['VARNAME_1'] == state:
patches[state].append(mpatches.Polygon(
shape, True,
))
##coloring the the provinces by group:
for state in NOR:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[0], edgecolor=colors[0]
))
for state in CEN:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[1], edgecolor=colors[1]
))
for state in SOU:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[2], edgecolor=colors[2]
))
for state in MEK:
ax.add_collection(PatchCollection(
patches[state], facecolor = colors[3], edgecolor=colors[3]
))
NOR_patch = mpatches.Patch(color=colors[0], label='Rate: 34.85%')
CEN_patch = mpatches.Patch(color=colors[1], label='Rate: 25.61%')
SOU_patch = mpatches.Patch(color=colors[2], label='Rate: 32.66%')
MEK_patch = mpatches.Patch(color=colors[3], label='Rate: 20.02%')
plt.legend(handles=[NOR_patch, CEN_patch, SOU_patch, MEK_patch])
plt.show()
结果符合预期：
请注意，我只能在 Python 3.6 下测试代码，因此可能需要进行一些调整。希望这有帮助。