Skip to content

Latest commit

 

History

History
106 lines (71 loc) · 3.77 KB

basemap.md

File metadata and controls

106 lines (71 loc) · 3.77 KB
Raw

Geo ploting with Basemap

The matplotlib basemap toolkit is a library for plotting 2D data on maps in Python.

Installation

Option 1:

The recommended installation method for Basemap is using Anaconda and the conda-forge channel. In the Anaconda Prompt run:

$ conda install -c anaconda basemap

You might also need to run the following command to install PROJ, which is a required dependency of Basemap:

$ conda install -c conda-forge proj

If the installation was sucessful you should now be able to run the following import in the Python (Anaconda) prompt without any errors:

from mpl_toolkits.basemap import Basemap

Option 2:

If you are on Windows you can also install the binaries directly. This worked better for me than installing through Anaconda and conda-forge. Download the Basemap and PROJ binaries. Make sure you download the correct binary for your Python version. For instance, if you have Python 3.7 64-bit make sure to download the pyproj‑2.4.2.post1‑cp37‑cp37m‑win_amd64.whl and basemap‑1.2.1‑cp37‑cp37m‑win_amd64.whl files. The cp37 indicates Python version and amd64 the 64-bit version. You can now install both libraries with pip.

$ pip install pyproj‑2.4.2.post1‑cp37‑cp37m‑win_amd64.whl
$ pip install basemap‑1.2.1‑cp37‑cp37m‑win_amd64.whl

Test the instalation by running:

from mpl_toolkits.basemap import Basemap

Ploting a simple map

Let's plot a simple world map.

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

m = Basemap(projection='mill',llcrnrlat=-90, urcrnrlat=90, llcrnrlon=-180, urcrnrlon=180, resolution='c')

# Draw map features
m.drawcoastlines()
m.fillcontinents(color='#072B57',lake_color='#FFFFFF')

# Draw parallels and meridians
m.drawparallels(np.arange(-90.,91.,30.))
m.drawmeridians(np.arange(-180.,181.,60.))

m.drawmapboundary(fill_color='#FFFFFF')
plt.title("Basemap Example!")
plt.show()

projection='mill' is the map projection. There are multiple projections availlable. Check here.

llcrnrlat, llcrnrlon, urcrnrlat, and urcrnrlon are the latitude and longitude values of the lower left and upper right corners of the map.

There are three resolution levels: resolution='c' (used above) is crude resolution but faster render time. There is also resolution='l' for low resolution and resolution='h' for high resolution, which represent increasing map resolution and increased render time. Unless coastlines or lakes are really important to you crude resolution is usually enough.

Drawing other map features:

m.drawcountries()  # draw countries
m.drawstates()  # draw states
m.drawrivers()  # draw rivers
m.bluemarble()  # satellite style map

Ploting coordinates

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt

m = Basemap(projection='mill',llcrnrlat=-90, urcrnrlat=90, llcrnrlon=-180, urcrnrlon=180, resolution='c')
m.drawcoastlines()
m.fillcontinents(color='#072B57',lake_color='#FFFFFF')
m.drawmapboundary(fill_color='#FFFFFF')

lat, lon = 29.7630, -95.3630  # define the coordinates
x,y = m(lon, lat)  # convert to Basemap system using your map
m.plot(x, y, 'ro', markersize=20, alpha=.5)  # plot and specify marker size and marker fill transparency

plt.title("Basemap Example!")
plt.show()

References: