使用底图在地图上绘制轨迹

Question

import numpy as np
data = np.loadtxt('path-tracks.csv',dtype=np.str,delimiter=',',skiprows=1)
print data

[['19.70' '-95.20' '2/5/04 6:45 AM' '1' '-38' 'CCM']
['19.70' '-94.70' '2/5/04 7:45 AM' '1' '-48' 'CCM']
['19.30' '-93.90' '2/5/04 8:45 AM' '1' '-60' 'CCM']
['19.00' '-93.50' '2/5/04 9:45 AM' '1' '-58' 'CCM']
['19.00' '-92.80' '2/5/04 10:45 AM' '1' '-50' 'CCM']
['19.20' '-92.60' '2/5/04 11:45 AM' '1' '-40' 'CCM']
['19.90' '-93.00' '2/5/04 12:45 PM' '1' '-43' 'CCM']
['20.00' '-92.80' '2/5/04 1:15 PM' '1' '-32' 'CCM']
['23.10' '-100.20' '30/5/04 4:45 AM' '2' '-45' 'SCME']
['23.20' '-100.00' '30/5/04 5:45 AM' '2' '-56' 'SCME']
['23.30' '-100.00' '30/5/04 6:45 AM' '2' '-48' 'SCME']
['23.30' '-100.20' '30/5/04 7:45 AM' '2' '-32' 'SCME']
['23.40' '-99.00' '31/5/04 3:15 AM' '3' '-36' 'SCM']
['23.50' '-98.90' '31/5/04 4:15 AM' '3' '-46' 'SCM']
['23.60' '-98.70' '31/5/04 5:15 AM' '3' '-68' 'SCM']
['23.70' '-98.80' '31/5/04 6:15 AM' '3' '-30' 'SCM']]

使用上面的代码我得到一个数组,其列代表:[Lat,Lon,Date,Identifier,Temperatures,Category].现在,我将放置一个代码,允许我绘制墨西哥地图上的第一和第二列:

#!/usr/bin/python
#Project Storm: Plot trajectories of convective systems
#import libraries

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

# Plot a map for Mexico

m = Basemap(projection='cyl', llcrnrlat=12, urcrnrlat=35,llcrnrlon=-120, urcrnrlon=-80, resolution='c', area_thresh=1000.)
m.bluemarble()
m.drawcoastlines(linewidth=0.5)
m.drawcountries(linewidth=0.5)
m.drawstates(linewidth=0.5)

#Draw parallels and meridians

m.drawparallels(np.arange(10.,35.,5.))
m.drawmeridians(np.arange(-120.,-80.,10.))
m.drawmapboundary(fill_color='aqua')

#Open file whit numpy

data = np.loadtxt('path-tracks.csv', dtype=np.str,delimiter=',', skiprows=1)
latitude = data[:,0]
longitude = data[:,1]

#Convert latitude and longitude to coordinates X and Y

x, y = m(longitude, latitude)

#Plot the points on the map

pl.plot(x,y,'ro-')
pl.show()

绘制在地图上的点,对应于三条不同的路径.Mi最后的想法是画一条线连接与每条路径相关的点,我该怎么做？

是否可以为每条路径绘制标识符或标记？

我如何设置图形的大小,以便它可以区分点之间的分离？

Answer 1

可以通过简单地创建figure前调用来设置图形的大小Basemap.我使用Pandas来读取CSV,因为它允许轻松分组(每个路径).如果你不想使用Pandas,你可能会通过迭代np.unique('cat')或其他东西获得相同的结果.如果您使用datetimepandas作为索引,则在CSV未排序的情况下,您的点会自动按时间排序.

通过绘制标识符,我不确定你的意思.图例可以区分路径,但您也可以'Cat'在地图的起点或终点绘制地图.

您的地图属性会使这些小路径稍微"缩小".使用ax = pl.gca()并ax.set_xlim()允许您在mapcoordinates中设置边界框.您可以从路径中的最大和最小坐标+某个缓冲区中获得.

import numpy as np
from mpl_toolkits.basemap import Basemap
import  matplotlib.pyplot as pl
import pandas as pd

fig = plt.figure(figsize=(12,12))

# Plot a map for Mexico
m = Basemap(projection='cyl', llcrnrlat=12, urcrnrlat=35,llcrnrlon=-120, urcrnrlon=-80, resolution='c', area_thresh=1000.)
m.bluemarble()
m.drawcoastlines(linewidth=0.5)
m.drawcountries(linewidth=0.5)
m.drawstates(linewidth=0.5)

#Draw parallels and meridians
m.drawparallels(np.arange(10.,35.,5.))
m.drawmeridians(np.arange(-120.,-80.,10.))
m.drawmapboundary(fill_color='aqua')

colors = {'CCM': 'red', 'SCME': 'white', 'SCM': 'yellow'}

for cat, track in df.groupby('Cat'):

    latitude = track.Lat.values
    longitude = track.Lon.values

    #Convert latitude and longitude to coordinates X and Y
    x, y = m(longitude, latitude)

    #Plot the points on the map
    pl.plot(x,y,'-', label=cat, color=colors[cat])

lg = pl.legend()
lg.get_frame().set_facecolor('grey')