使用for循环制作来自不同纬度和经度坐标线的线路图

Question

我的代码的目的是使用宾夕法尼亚收费公路上的出口的纬度和经度进行粗糙的路线图，在每个出口之间绘制一条线。

我正在使用for循环在地图上每次循环时绘制一条线。如果我用力编码纬度和经度，这有效，但是一旦插入变量，就没有绘制任何内容。由于坐标为顺序，我只是每次循环时都会增加索引以获取下一个坐标。我已经打印了循环内部的变量，并验证了它们具有所需的值。我尝试将值放入有序对，但是绘图功能不喜欢我使用NPARRAYS。我不确定我是否缺少一些简单的东西，但我感谢任何输入。

import netCDF4 as nc
import numpy as np
import matplotlib.pyplot as plt
import cartopy
import cartopy.crs as ccrs
from datetime import datetime, timedelta

# Open the file for highway metadata to read csv data
highway_metadata = open('milestone3data.csv', 'r')
metafile = csv.reader(highway_metadata, delimiter = ',')

# Create empty lists with highway data
highway_loc = []
highway_name = []
highway_lat = []
highway_lon = []
highway_dist = []

# Loop to transfer the csv file's data into the lists
for i in metafile:
    highway_loc.append(i[0])
    highway_name.append(i[1])
    highway_lat.append(float(i[2]))
    highway_lon.append(float(i[3]))
    highway_dist.append(i[4])

def road_map():

    enhighway_lat = enumerate(highway_lat)
    enhighway_lon = enumerate(highway_lon)
    orthographic = ccrs.Orthographic()
    platecarree = ccrs.PlateCarree()
    proj = ccrs.Orthographic(central_longitude = -75, central_latitude = 41)
    ax = plt.axes(projection=proj)
  # Set up the background
    ax.add_feature(cartopy.feature.COASTLINE)
    ax.add_feature(cartopy.feature.STATES)
    ax.set_extent((-85,-70,36,45),crs=ccrs.PlateCarree())

    for i,j in enhighway_lat:
        for k,l in enhighway_lon:
            if i or k <= 30:
                plt.plot([highway_lon[k], highway_lon[k+1]], [highway_lat[i], highway_lat[i+1]], color='black', linewidth=1, marker='o', markersize=3, transform=ccrs.PlateCarree())

    plt.savefig('cartopytest7.png')
    plt.show
road_map()

[This is my most recent output from the program][1]

  [1]: https://i.sstatic.net/lgFrN.png

CSV文件内容：（英里标记，出口名称，纬度，经度，从收费公路开始的英里）

2,Gateway (Ohio Connection),40.90419167,-80.47158333,1.43
10,New Castle,40.83018056,-80.34196111,10.7
13,Beaver Valley,40.8143,-80.307925,12.87
28,Cranberry,40.67983889,-80.09537778,28.47
30,Warrendale,40.65533889,-80.06116667,31
39,Butler Valley,40.60913611,-79.91924444,39.1
48,Allegheny Valley,40.542025,-79.81022222,47.73
57,Pittsburgh,40.43808889,-79.74956944,56.44
67,Irwin,40.31342778,-79.65476111,67.22
75,New Stanton,40.22173333,-79.59573333,75.39
91,Donegal,40.10915,-79.35231944,90.69
110,Somerset,40.02033056,-79.05208056,109.91
146,Bedford,40.05013889,-78.48615,145.5
161,Breezewood,39.98721667,-78.24472778,161.5
180,Fort Littleton,40.05010556,-77.93954444,179.44
189,Willow Hill,40.09674167,-77.78441389,188.59
201,Blue Mountain,40.15755278,-77.58403333,201.29
226,Carlisle,40.22814722,-77.14782222,226.54
236,Gettysburg Pike,40.19569444,-76.95665556,236.22
242,Harrisburg West Shore,40.21216667,-76.85765278,241.87
247,Harrisburg East,40.21501111,-76.78060278,247.38
266,Lebanon-Lancaster,40.22974444,-76.43095,266.45
286,Reading,40.21805,-76.05189167,286.09
298,Morgantown,40.15990278,-75.88311667,298.33
312,Downingtown,40.06838611,-75.66450278,311.93
320,SR29,40.07641667,-75.52881944,319.33
326,Valley Forge,40.09296667,-75.39591111,326.62
333,Norristown,40.11101111,-75.27921389,333.28
339,Fort Washington,40.13231944,-75.17092222,338.36
340,Virginia Dr,40.13854444,-75.16268611,339.8
343,Willow Grove,40.16166111,-75.11271111,342.91
351,Bensalem,40.13200278,-74.96229444,351.49
352,Street Rd,40.13150833,-74.96445,351.89
353,Neshaminy Falls,40.12916667,-74.94150278,352.67

Answer 1

好的，根据上面的讨论，请参见下文。

注意：

• 我正在使用pandas DataFames轻松使用.csv文件。 名称字段是列名。
• 根本不使用拼字图投影。
• 遍历一次高速公路清单一次出口。在每个索引上，正在提取当前和下一个退出的数据 - 确定有更多的“ Pythonic”方法可以做到这一点，但这至少可以读取。




• 编辑：循环中的最终索引是Length-1
• 更新：感谢@SimonWillerton，我删除了循环。

import netCDF4 as nc
import numpy as np
import matplotlib.pyplot as plt
import cartopy
import cartopy.crs as ccrs
import pandas as pd

def road_map():    
    # Open the file for highway metadata to read csv data
    highway_metadata = pd.read_csv('milestone3data.csv', names=["loc", "name", "lat", "lon", "dist"])

    proj = ccrs.PlateCarree(central_longitude = -75)
    ax   = plt.axes(projection=proj)
    ax.add_feature(cartopy.feature.COASTLINE)
    ax.add_feature(cartopy.feature.STATES)
    ax.set_extent((-85,-70,36,45),crs=ccrs.PlateCarree())
    
    plt.plot(highway_metadata['lon'], highway_metadata['lat'], \
             color='black', linewidth=1, marker='o', markersize=3, transform=ccrs.PlateCarree())
                       
    plt.savefig('cartopytest7.png')

if __name__ == '__main__':
    road_map()

这会产生以下图像：

，基于Wikipedia的宾夕法尼亚收费公路的这张图像（source = https://commons.wikimedia.org/wiki/file:pennsylvania_turnpike_map.svg#file ）我认为我们有成功

Answer 2

看起来您正试图用plt.plot（）语句做一些相当复杂的事情。您有纵向清单和固定列表；这就是您在Matplotlib中的点之间绘制所需的一切，因此无需枚举或循环循环列表。以下行应该解决问题。

plt.plot(highway_lon, highway_lat, color='black', linewidth=1, marker='o', markersize=3, transform=ccrs.PlateCarree())

这是删除一些不必要的位置的代码。

import csv
import numpy as np
import matplotlib.pyplot as plt
import cartopy
import cartopy.crs as ccrs

# Open the file for highway metadata to read csv data
highway_metadata = open('milestone3data.csv', 'r')
metafile = csv.reader(highway_metadata, delimiter = ',')

# Create empty lists with highway data
highway_loc = []
highway_name = []
highway_lat = []
highway_lon = []
highway_dist = []

# Loop to transfer the csv file's data into the lists
for i in metafile:
    highway_loc.append(i[0])
    highway_name.append(i[1])
    highway_lat.append(float(i[2]))
    highway_lon.append(float(i[3]))
    highway_dist.append(i[4])

def road_map():
    fig = plt.figure(figsize=(10, 10))
    proj = ccrs.Orthographic(central_longitude = -75, 
                             central_latitude = 41)
    ax = plt.axes(projection=proj)
    ax.set_extent((-85,-70,36,45),crs=ccrs.PlateCarree())
    # Set up the background
    ax.add_feature(cartopy.feature.COASTLINE)
    ax.add_feature(cartopy.feature.STATES)

    plt.plot(highway_lon, highway_lat, 
             color='black', linewidth=1, marker='o', markersize=3, 
             transform=ccrs.PlateCarree())

    plt.savefig('cartopytest7.png')
    plt.show
    
road_map()