如何将模型中带有颜色的数据绘制到 matplotlib 底图上？为什么数据不显示？

Question

我正在尝试从绘制在底图上的模型中获取数据输出。我可以看到地图，但看不到点。问题是什么？我正在为 python 2.7 使用最新版本的 scikit-learn 和底图。我有以下代码：

dataframe = pd.read_csv('powerplants.csv') # CSV file that contains latitude column, longitude column, and id for the powerplant
colormap = np.arange(500)
labels = modeloutput.labels_ # assume this is output of my model

fig = plt.figure()
ax = fig.add_subplot(111, axisbg='w', frame_on=True)
fig.set_size_inches(18.5, 10.5)
map_points = [...] # assume this is a list populated with coordinates from the csv
# Plot the clusters on the map
# m is a basemap object
m.scatter(
         [geom.x for geom in map_points],
         [geom.y for geom in map_points],
         20, marker='o', lw=.25,
         c = colormap(labels.astype(float)),
         alpha =0.9, antialiased=True,
         zorder=3)
m.fillcontinents(color='#555555')
plt.show()

Answer 1

这个例子修改自official example。在散点图中使用颜色图的关键部分是：

x.data 和 y.data 是转换后的坐标。
c = np.random.randint(1, 500, size=len(lats)) 是映射到颜色图中对应于每个点的颜色的值。

您可能不需要的一些部分是：

import urllib, os
from netCDF4 import Dataset
import numpy as np

filename, _ = urllib.urlretrieve('http://coastwatch.pfeg.noaa.gov/erddap/tabledap/apdrcArgoAll.nc?longitude,latitude,time&longitude>=0&longitude<=360&latitude>=-90&latitude<=90&time>=2010-01-01&time<=2010-01-08&distinct()')
dset = Dataset(filename)
lats = dset.variables['latitude'][:]
lons = dset.variables['longitude'][:]
dset.close()
os.remove(filename)
c = np.random.randint(1, 500, size=len(lats))

x, y = m(lons,lats)

This part is used for generating an data sample. You might want to replace it with your real data.

from mpl_toolkits.axes_grid1 import make_axes_locatable

divider = make_axes_locatable(ax)
fig.colorbar(pc, cax=divider.append_axes("right", size="5%", pad=0.05))

This is a direct application of bogatron's answer to make the size of colorbar matches the plot. It's your choice of keeping it or not.

import urllib, os

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import make_axes_locatable
from mpl_toolkits.basemap import Basemap
from netCDF4 import Dataset
import numpy as np

# data downloaded from the form at
# http://coastwatch.pfeg.noaa.gov/erddap/tabledap/apdrcArgoAll.html
filename, _ = urllib.urlretrieve('http://coastwatch.pfeg.noaa.gov/erddap/tabledap/apdrcArgoAll.nc?longitude,latitude,time&longitude>=0&longitude<=360&latitude>=-90&latitude<=90&time>=2010-01-01&time<=2010-01-08&distinct()')
dset = Dataset(filename)
lats = dset.variables['latitude'][:]
lons = dset.variables['longitude'][:]
dset.close()
os.remove(filename)
c = np.random.randint(1, 500, size=len(lats))

# draw map with markers for float locations
fig = plt.figure()
ax = fig.add_subplot(111, axisbg='w', frame_on=True)
fig.set_size_inches(18.5, 10.5)
m = Basemap(lon_0=180, ax=ax)
x, y = m(lons,lats)
pc = m.scatter(x.data, y.data, 20, marker='o', c=c, lw=.25, alpha =0.9, antialiased=True, zorder=3, cmap='summer')
m.fillcontinents(color='#555555')
divider = make_axes_locatable(ax)
fig.colorbar(pc, cax=divider.append_axes("right", size="5%", pad=0.05))
plt.show()

如何将模型中带有颜色的数据绘制到 matplotlib 底图上？为什么数据不显示？

How do I plot data with color from my model onto matplotlib Basemap? Why is data not showing up?

python

matplotlib

scikit-learn

matplotlib-basemap