Matplotlib basemap:脱机映射

Question

您好，当我使用具有最大分辨率（resolution='f'）的basemap时，绘制它需要很多时间。在

对于我的项目，我必须使用这个分辨率，但因为程序必须由用户使用，我希望它尽可能快。在

它是不是因为它从某个在线存储库下载了地图？在

有没有办法下载我需要的地图并离线绘制？在

这是一个MWE：

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap

lon_min = -10.5
lon_max = 2.0
lat_min = 50.0
lat_max = 59.7

coastlinesMap = Basemap(suppress_ticks=False, projection='cyl',
                        llcrnrlat=lat_min, urcrnrlat=lat_max,
                        llcrnrlon=lon_min, urcrnrlon=lon_max,
                        resolution='f')

n = 100
x = np.linspace(lon_min, lon_max, n)
y = np.linspace(lat_min, lat_max, n)
lon, lat = np.meshgrid(x, y)
z = np.zeros((n, n))
for i in range(n):
    for j in range(n):
        z[i, j] = x[i] + y[j]

fig = plt.figure("test")
ax = fig.add_subplot(111)
cf = ax.contourf(lon, lat, z, cmap="jet")
ax.set_xlabel("lon")
ax.set_ylabel("lat")
ax.add_collection(coastlinesMap.drawcoastlines(linewidth=0.25))
coastlinesMap.fillcontinents(color="green")
fig.colorbar(cf)

plt.show()

编辑

我只想澄清一下，当图显示出来时，我可以缩放或平移等等，而且变化很快，生成coastlineMap的速度很慢。在

Answer 1

通过@ImportanceOfBeingErnest的链接，环顾四周，我用cPickle解决了我的问题。在

我在下面报告解决方案

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
import time
from six.moves import cPickle

lon_min = -10.5
lon_max = 2.0
lat_min = 50.0
lat_max = 59.7

t1 = time.clock()
coastlinesMap = Basemap(suppress_ticks=False, projection='cyl',
                        llcrnrlat=lat_min, urcrnrlat=lat_max,
                        llcrnrlon=lon_min, urcrnrlon=lon_max,
                        resolution='f')
print(time.clock()-t1,' secs to create original Basemap instance')
cPickle.dump(coastlinesMap, open('UKmap.pickle', 'wb'), -1)

n = 100
x = np.linspace(lon_min, lon_max, n)
y = np.linspace(lat_min, lat_max, n)
lon, lat = np.meshgrid(x, y)
z = np.zeros((n, n))
for i in range(n):
    for j in range(n):
        z[i, j] = x[i] + y[j]

fig = plt.figure("test")
ax = fig.add_subplot(111)
cf = ax.contourf(lon, lat, z, cmap="jet")
ax.set_xlabel("lon")
ax.set_ylabel("lat")
ax.add_collection(coastlinesMap.drawcoastlines(linewidth=0.25))
coastlinesMap.fillcontinents(color="green")
fig.colorbar(cf)

t1 = time.clock()
m2 = cPickle.load(open('UKmap.pickle','rb'))

fig = plt.figure("test")
ax = fig.add_subplot(111)
ax.set_xlabel("lon")
ax.set_ylabel("lat")
ax.add_collection(m2.drawcoastlines(linewidth=0.25))
m2.drawcountries()
print(time.clock()-t1,' secs to plot using using a pickled Basemap instance')

plt.show()