1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
from __future__ import (absolute_import, division, print_function)
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap as Basemap
from matplotlib.colors import rgb2hex, Normalize
from matplotlib.patches import Polygon
from matplotlib.colorbar import ColorbarBase
fig, ax = plt.subplots()
# Lambert Conformal map of lower 48 states.
m = Basemap(llcrnrlon=-119,llcrnrlat=20,urcrnrlon=-64,urcrnrlat=49,
projection='lcc',lat_1=33,lat_2=45,lon_0=-95)
# Mercator projection, for Alaska and Hawaii
m_ = Basemap(llcrnrlon=-190,llcrnrlat=20,urcrnrlon=-143,urcrnrlat=46,
projection='merc',lat_ts=20) # do not change these numbers
#%% --------- draw state boundaries ----------------------------------------
## data from U.S Census Bureau
## http://www.census.gov/geo/www/cob/st2000.html
shp_info = m.readshapefile('st99_d00','states',drawbounds=True,
linewidth=0.45,color='gray')
shp_info_ = m_.readshapefile('st99_d00','states',drawbounds=False)
## population density by state from
## http://en.wikipedia.org/wiki/List_of_U.S._states_by_population_density
popdensity = {
'New Jersey': 438.00,
'Rhode Island': 387.35,
'Massachusetts': 312.68,
'Connecticut': 271.40,
'Maryland': 209.23,
'New York': 155.18,
'Delaware': 154.87,
'Florida': 114.43,
'Ohio': 107.05,
'Pennsylvania': 105.80,
'Illinois': 86.27,
'California': 83.85,
'Hawaii': 72.83,
'Virginia': 69.03,
'Michigan': 67.55,
'Indiana': 65.46,
'North Carolina': 63.80,
'Georgia': 54.59,
'Tennessee': 53.29,
'New Hampshire': 53.20,
'South Carolina': 51.45,
'Louisiana': 39.61,
'Kentucky': 39.28,
'Wisconsin': 38.13,
'Washington': 34.20,
'Alabama': 33.84,
'Missouri': 31.36,
'Texas': 30.75,
'West Virginia': 29.00,
'Vermont': 25.41,
'Minnesota': 23.86,
'Mississippi': 23.42,
'Iowa': 20.22,
'Arkansas': 19.82,
'Oklahoma': 19.40,
'Arizona': 17.43,
'Colorado': 16.01,
'Maine': 15.95,
'Oregon': 13.76,
'Kansas': 12.69,
'Utah': 10.50,
'Nebraska': 8.60,
'Nevada': 7.03,
'Idaho': 6.04,
'New Mexico': 5.79,
'South Dakota': 3.84,
'North Dakota': 3.59,
'Montana': 2.39,
'Wyoming': 1.96,
'Alaska': 0.42}
#%% -------- choose a color for each state based on population density. -------
colors={}
statenames=[]
cmap = plt.cm.hot_r # use 'reversed hot' colormap
vmin = 0; vmax = 450 # set range.
norm = Normalize(vmin=vmin, vmax=vmax)
for shapedict in m.states_info:
statename = shapedict['NAME']
# skip DC and Puerto Rico.
if statename not in ['District of Columbia','Puerto Rico']:
pop = popdensity[statename]
# calling colormap with value between 0 and 1 returns
# rgba value. Invert color range (hot colors are high
# population), take sqrt root to spread out colors more.
colors[statename] = cmap(np.sqrt((pop-vmin)/(vmax-vmin)))[:3]
statenames.append(statename)
#%% --------- cycle through state names, color each one. --------------------
for nshape,seg in enumerate(m.states):
# skip DC and Puerto Rico.
if statenames[nshape] not in ['Puerto Rico', 'District of Columbia']:
color = rgb2hex(colors[statenames[nshape]])
poly = Polygon(seg,facecolor=color,edgecolor=color)
ax.add_patch(poly)
AREA_1 = 0.005 # exclude small Hawaiian islands that are smaller than AREA_1
AREA_2 = AREA_1 * 30.0 # exclude Alaskan islands that are smaller than AREA_2
AK_SCALE = 0.19 # scale down Alaska to show as a map inset
HI_OFFSET_X = -1900000 # X coordinate offset amount to move Hawaii "beneath" Texas
HI_OFFSET_Y = 250000 # similar to above: Y offset for Hawaii
AK_OFFSET_X = -250000 # X offset for Alaska (These four values are obtained
AK_OFFSET_Y = -750000 # via manual trial and error, thus changing them is not recommended.)
for nshape, shapedict in enumerate(m_.states_info): # plot Alaska and Hawaii as map insets
if shapedict['NAME'] in ['Alaska', 'Hawaii']:
seg = m_.states[int(shapedict['SHAPENUM'] - 1)]
if shapedict['NAME'] == 'Hawaii' and float(shapedict['AREA']) > AREA_1:
seg = [(x + HI_OFFSET_X, y + HI_OFFSET_Y) for x, y in seg]
color = rgb2hex(colors[statenames[nshape]])
elif shapedict['NAME'] == 'Alaska' and float(shapedict['AREA']) > AREA_2:
seg = [(x*AK_SCALE + AK_OFFSET_X, y*AK_SCALE + AK_OFFSET_Y)\
for x, y in seg]
color = rgb2hex(colors[statenames[nshape]])
poly = Polygon(seg, facecolor=color, edgecolor='gray', linewidth=.45)
ax.add_patch(poly)
ax.set_title('United states population density by state')
#%% --------- Plot bounding boxes for Alaska and Hawaii insets --------------
light_gray = [0.8]*3 # define light gray color RGB
x1,y1 = m_([-190,-183,-180,-180,-175,-171,-171],[29,29,26,26,26,22,20])
x2,y2 = m_([-180,-180,-177],[26,23,20]) # these numbers are fine-tuned manually
m_.plot(x1,y1,color=light_gray,linewidth=0.8) # do not change them drastically
m_.plot(x2,y2,color=light_gray,linewidth=0.8)
#%% --------- Show color bar ---------------------------------------
ax_c = fig.add_axes([0.9, 0.1, 0.03, 0.8])
cb = ColorbarBase(ax_c,cmap=cmap,norm=norm,orientation='vertical',
label=r'[population per $\mathregular{km^2}$]')
plt.show()
|
