python-为什么Matplotlib底图不显示岛?
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了python-为什么Matplotlib底图不显示岛?,小编现在分享给大家,供广大互联网技能从业者学习和参考。文章包含5060字,纯文字阅读大概需要8分钟。
内容图文
![python-为什么Matplotlib底图不显示岛?](/upload/InfoBanner/zyjiaocheng/650/c648e16741a542c4812e4c9b3807c925.jpg)
我一直在使用matplotlib和底图来显示有关纽约市的一些信息.到目前为止,我一直在关注this guide,但遇到了一个问题.我试图在可视化中显示曼哈顿岛,但我不知道为什么底图没有将其显示为岛.
这是底图为我提供的可视化效果:
这是我正在使用的边界框的屏幕截图:
这是生成图像的代码:
wl = -74.04006
sl = 40.683092
el = -73.834067
nl = 40.88378
m = Basemap(resolution='f', # c, l, i, h, f or None
projection='merc',
area_thresh=50,
lat_0=(wl + sl)/2, lon_0=(el + nl)/2,
llcrnrlon= wl, llcrnrlat= sl, urcrnrlon= el, urcrnrlat= nl)
m.drawmapboundary(fill_color='#46bcec')
m.fillcontinents(color='#f2f2f2',lake_color='#46bcec')
m.drawcoastlines()
m.drawrivers()
我以为它可能会考虑河流之间的水,但是m.drawrivers()似乎没有解决问题.任何帮助显然都非常感激.
提前致谢!
解决方法:
一种为您的地块获取质量更好的基础地图的方法是,以适当的缩放级别从Web地图图块构建一个.在这里,我演示了如何从openstreetmap Web地图服务器获取它们.在这种情况下,我将缩放级别设置为10,并获得2个地图图块,以将其合并为单个图像数组.缺点之一是组合图像的范围始终大于我们要求的值.这是工作代码:
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
import math
import urllib2
import StringIO
from PIL import Image
# === Begin block1 ===
# Credit: BerndGit, answered Feb 15 '15 at 19:47. And ...
# Source: https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
def deg2num(lat_deg, lon_deg, zoom):
'''Lon./lat. to tile numbers'''
lat_rad = math.radians(lat_deg)
n = 2.0 ** zoom
xtile = int((lon_deg + 180.0) / 360.0 * n)
ytile = int((1.0 - math.log(math.tan(lat_rad) + (1 / math.cos(lat_rad))) / math.pi) / 2.0 * n)
return (xtile, ytile)
def num2deg(xtile, ytile, zoom):
'''Tile numbers to lon./lat.'''
n = 2.0 ** zoom
lon_deg = xtile / n * 360.0 - 180.0
lat_rad = math.atan(math.sinh(math.pi * (1 - 2 * ytile / n)))
lat_deg = math.degrees(lat_rad)
return (lat_deg, lon_deg) # NW-corner of the tile.
def getImageCluster(lat_deg, lon_deg, delta_lat, delta_long, zoom):
# access map tiles from internet
# no access/key or password is needed
smurl = r"http://a.tile.openstreetmap.org/{0}/{1}/{2}.png"
# useful snippet: smurl.format(zoom, xtile, ytile) -> complete URL
# x increases L-R; y Top-Bottom
xmin, ymax =deg2num(lat_deg, lon_deg, zoom) # get tile numbers (x,y)
xmax, ymin =deg2num(lat_deg+delta_lat, lon_deg+delta_long, zoom)
# PIL is used to build new image from tiles
Cluster = Image.new('RGB',((xmax-xmin+1)*256-1,(ymax-ymin+1)*256-1) )
for xtile in range(xmin, xmax+1):
for ytile in range(ymin, ymax+1):
try:
imgurl = smurl.format(zoom, xtile, ytile)
print("Opening: " + imgurl)
imgstr = urllib2.urlopen(imgurl).read()
# TODO: study, what these do?
tile = Image.open(StringIO.StringIO(imgstr))
Cluster.paste(tile, box=((xtile-xmin)*256 , (ytile-ymin)*255))
except:
print("Couldn't download image")
tile = None
return Cluster
# ===End Block1===
# Credit to myself
def getextents(latmin_deg, lonmin_deg, delta_lat, delta_long, zoom):
'''Return LL and UR, each with (long,lat) of real extent of combined tiles.
latmin_deg: bottom lat of extent
lonmin_deg: left long of extent
delta_lat: extent of lat
delta_long: extent of long, all in degrees
'''
# Tile numbers(x,y): x increases L-R; y Top-Bottom
xtile_LL, ytile_LL = deg2num(latmin_deg, lonmin_deg, zoom) #get tile numbers as specified by (x, y)
xtile_UR, ytile_UR = deg2num(latmin_deg + delta_lat, lonmin_deg + delta_long, zoom)
# from tile numbers, we get NW corners
lat_NW_LL, lon_NW_LL = num2deg(xtile_LL, ytile_LL, zoom)
lat_NW_LLL, lon_NW_LLL = num2deg(xtile_LL, ytile_LL+1, zoom) # next down below
lat_NW_UR, lon_NW_UR = num2deg(xtile_UR, ytile_UR, zoom)
lat_NW_URR, lon_NW_URR = num2deg(xtile_UR+1, ytile_UR, zoom) # next to the right
# get extents
minLat = lat_NW_LLL
minLon = lon_NW_LL
maxLat = lat_NW_UR
maxLon = lon_NW_URR
return (minLon, maxLon, minLat, maxLat) # (left, right, bottom, top) in degrees
# OP's values of extents for target area to plot
# some changes here (with larger zoom level) may lead to better final plot
wl = -74.04006
sl = 40.683092
el = -73.834067
nl = 40.88378
lat_deg = sl
lon_deg = wl
d_lat = nl - sl
d_long = el - wl
zoom = 10 # zoom level
# Acquire images. The combined images will be slightly larger that the extents
timg = getImageCluster(lat_deg, lon_deg, d_lat, d_long, zoom)
# This computes real extents of the combined tile images, and get (left, right, bottom, top)
latmin_deg, lonmin_deg, delta_lat, delta_long = sl, wl, nl-sl, el-wl
(left, right, bottom, top) = getextents(latmin_deg, lonmin_deg, delta_lat, delta_long, zoom) #units: degrees
# Set Basemap with proper parameters
m = Basemap(resolution='h', # h is nice
projection='merc',
area_thresh=50,
lat_0=(bottom + top)/2, lon_0=(left + right)/2,
llcrnrlon=left, llcrnrlat=bottom, urcrnrlon=right, urcrnrlat=top)
fig = plt.figure()
fig.set_size_inches(10, 12)
m.imshow(np.asarray(timg), extent=[left, right, bottom, top], origin='upper' )
m.drawcoastlines(color='gray', linewidth=3.0) # intentionally thick line
#m.fillcontinents(color='#f2f2f2', lake_color='#46bcec', alpha=0.6)
plt.show()
希望能帮助到你.结果图:
编辑
裁剪图像以获得确切的绘图区域并不困难. PIL模块可以处理. Numpy的数组切片也可以.
内容总结
以上是互联网集市为您收集整理的python-为什么Matplotlib底图不显示岛?全部内容,希望文章能够帮你解决python-为什么Matplotlib底图不显示岛?所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错,欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 gblab@vip.qq.com 举报,一经查实,本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。