[英]Plotting locations on a NYC map using geopandas and geoplot
[英]Plotting a map using geopandas and matplotlib
我有來自英國伯明翰的 6 個坐標的小 csv。 我用 Pandas 讀取了 csv,然后將其轉換為 GeoPandas DataFrame,使用 Shapely Points 更改我的緯度和經度列。 我現在正在嘗試繪制我的 GeoDataframe,我能看到的只是點。 我如何同時表示伯明翰地圖? GeoPandas 上的良好文檔來源也將受到強烈贊賞。
from shapely.geometry import Point
import geopandas as gpd
import pandas as pd
df = pd.read_csv('SiteLocation.csv')
df['Coordinates'] = list(zip(df.LONG, df.LAT))
df['Coordinates'] = df['Coordinates'].apply(Point)
# Building the GeoDataframe
geo_df = gpd.GeoDataFrame(df, geometry='Coordinates')
geo_df.plot()
GeoPandas 文檔包含一個關於如何向地圖添加背景的示例 ( https://geopandas.readthedocs.io/en/latest/gallery/plotting_basemap_background.html ),下面有更詳細的解釋。
您將不得不處理tiles ,即通過網絡服務器提供的(png)圖像,其URL類似於
http://.../Z/X/Y.png
,其中 Z 是縮放級別, X 和 Y 標識圖塊
geopandas 的文檔展示了如何將圖塊設置為繪圖的背景,獲取正確的圖塊並完成所有其他困難的空間同步工作等......
假設 GeoPandas 已經安裝,你還需要contextily
包。 如果你在 windows 下,你可能想看看如何安裝 Contextily?
用例
創建一個 python 腳本並定義上下文輔助函數
import contextily as ctx def add_basemap(ax, zoom, url='http://tile.stamen.com/terrain/tileZ/tileX/tileY.png'): xmin, xmax, ymin, ymax = ax.axis() basemap, extent = ctx.bounds2img(xmin, ymin, xmax, ymax, zoom=zoom, url=url) ax.imshow(basemap, extent=extent, interpolation='bilinear') # restore original x/y limits ax.axis((xmin, xmax, ymin, ymax))
和玩
import matplotlib.pyplot as plt from shapely.geometry import Point import geopandas as gpd import pandas as pd # Let's define our raw data, whose epsg is 4326 df = pd.DataFrame({ 'LAT' :[-22.266415, -20.684157], 'LONG' :[166.452764, 164.956089], }) df['coords'] = list(zip(df.LONG, df.LAT)) # ... turn them into geodataframe, and convert our # epsg into 3857, since web map tiles are typically # provided as such. geo_df = gpd.GeoDataFrame( df, crs ={'init': 'epsg:4326'}, geometry = df['coords'].apply(Point) ).to_crs(epsg=3857) # ... and make the plot ax = geo_df.plot( figsize= (5, 5), alpha = 1 ) add_basemap(ax, zoom=10) ax.set_axis_off() plt.title('Kaledonia : From Hienghène to Nouméa') plt.show()
zoom
來為地圖找到合適的分辨率。
例如/即:
...這樣的決議暗中要求更改 x/y 限制。
試試df.unary_union 。 該函數將點聚合成單個幾何圖形。 Jupyter Notebook可以繪制它
只想添加有關縮放的用例,即根據新的xlim
和ylim
坐標更新底圖。 我想出的一個解決方案是:
xlim_changed
和ylim_changed
的ax
上設置回調plot_area
調用ax.get_xlim()
和ax.get_ylim()
ax
並重新繪制底圖和任何其他數據顯示首都的世界地圖示例。 當您放大地圖的分辨率時,您會注意到正在更新。
import geopandas as gpd
import matplotlib.pyplot as plt
import contextily as ctx
figsize = (12, 10)
osm_url = 'http://tile.stamen.com/terrain/{z}/{x}/{y}.png'
EPSG_OSM = 3857
EPSG_WGS84 = 4326
class MapTools:
def __init__(self):
self.cities = gpd.read_file(
gpd.datasets.get_path('naturalearth_cities'))
self.cities.crs = EPSG_WGS84
self.cities = self.convert_to_osm(self.cities)
self.fig, self.ax = plt.subplots(nrows=1, ncols=1, figsize=figsize)
self.callbacks_connect()
# get extent of the map for all cities
self.cities.plot(ax=self.ax)
self.plot_area = self.ax.axis()
def convert_to_osm(self, df):
return df.to_crs(epsg=EPSG_OSM)
def callbacks_connect(self):
self.zoomcallx = self.ax.callbacks.connect(
'xlim_changed', self.on_limx_change)
self.zoomcally = self.ax.callbacks.connect(
'ylim_changed', self.on_limy_change)
self.x_called = False
self.y_called = False
def callbacks_disconnect(self):
self.ax.callbacks.disconnect(self.zoomcallx)
self.ax.callbacks.disconnect(self.zoomcally)
def on_limx_change(self, _):
self.x_called = True
if self.y_called:
self.on_lim_change()
def on_limy_change(self, _):
self.y_called = True
if self.x_called:
self.on_lim_change()
def on_lim_change(self):
xlim = self.ax.get_xlim()
ylim = self.ax.get_ylim()
self.plot_area = (*xlim, *ylim)
self.blit_map()
def add_base_map_osm(self):
if abs(self.plot_area[1] - self.plot_area[0]) < 100:
zoom = 13
else:
zoom = 'auto'
try:
basemap, extent = ctx.bounds2img(
self.plot_area[0], self.plot_area[2],
self.plot_area[1], self.plot_area[3],
zoom=zoom,
url=osm_url,)
self.ax.imshow(basemap, extent=extent, interpolation='bilinear')
except Exception as e:
print(f'unable to load map: {e}')
def blit_map(self):
self.ax.cla()
self.callbacks_disconnect()
cities = self.cities.cx[
self.plot_area[0]:self.plot_area[1],
self.plot_area[2]:self.plot_area[3]]
cities.plot(ax=self.ax, color='red', markersize=3)
print('*'*80)
print(self.plot_area)
print(f'{len(cities)} cities in plot area')
self.add_base_map_osm()
self.callbacks_connect()
@staticmethod
def show():
plt.show()
def main():
map_tools = MapTools()
map_tools.show()
if __name__ == '__main__':
main()
使用以下 pip 安裝在 Linux Python3.8 上運行
affine==2.3.0
attrs==19.3.0
autopep8==1.4.4
Cartopy==0.17.0
certifi==2019.11.28
chardet==3.0.4
Click==7.0
click-plugins==1.1.1
cligj==0.5.0
contextily==1.0rc2
cycler==0.10.0
descartes==1.1.0
Fiona==1.8.11
geographiclib==1.50
geopandas==0.6.2
geopy==1.20.0
idna==2.8
joblib==0.14.0
kiwisolver==1.1.0
matplotlib==3.1.2
mercantile==1.1.2
more-itertools==8.0.0
munch==2.5.0
numpy==1.17.4
packaging==19.2
pandas==0.25.3
Pillow==6.2.1
pluggy==0.13.1
py==1.8.0
pycodestyle==2.5.0
pyparsing==2.4.5
pyproj==2.4.1
pyshp==2.1.0
pytest==5.3.1
python-dateutil==2.8.1
pytz==2019.3
rasterio==1.1.1
requests==2.22.0
Rtree==0.9.1
Shapely==1.6.4.post2
six==1.13.0
snuggs==1.4.7
urllib3==1.25.7
wcwidth==0.1.7
請注意對contextily==1.0rc2
特別要求
在 Windows 上,我使用 Conda (P3.7.3) 並且不要忘記設置用戶變量:
GDAL c:\\Users\\<username>\\Anaconda3\\envs\\<your environment>\\Library\\share\\gdal
PROJLIB c:\\Users\\<username>\\Anaconda3\\envs\\<your environment>\\Library\\share
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