[SOLVED] Plot points on offline map in Python

Plot points on offline map in Python

I'm using Spyder and have a couple of coordinates that I want to plot on a world map. Currently I use Folium, save data as an HTML-file and then open it in a webbrowser. My question is: is it possible to plot coordinates on a map without the use of the webbrowser? Or anything external for that matter? I was hoping there would be a package that enables me to plot everything and see it in Spyder itself.

Does anyone has an idea?

Solution

check out the cartopy module that provides numerous map projections as well as the ability to enhance your projection with numerous features (eg. land mass, oceans, coastlines, borders, etc)

It's not likely to be in your Python distribution so install it with

pip install cartopy

you'll also need matplotlib.pyplot but since you're plotting already I'll assume you have that.

It works by selecting a projection (a crs - coordinate reference system) for your map (eg Mercator, Platte Carre (flat plate - basically rectangular), etc.) Then select the crs that matches your data. The basic process is

create a set of axes with the desired map crs
add any features you want to those axes
set the extent (min/max longitude and min/max latitude) of the map to display
finally use any of the maplotlib.pyplot funtions to plot your data on those axes

Here is a simple of example of plotting 4 lon/lat locations in Africa using a scatter plot of long/lat pairs

import cartopy
import cartopy.crs as ccrs
import matplotlib.pyplot as plt


map_crs = ccrs.PlateCarree()
data_crs = ccrs.PlateCarree()


def fancify(axes):
    """add features to cartopy axes"""
    axes.stock_img()
    axes.add_feature(cartopy.feature.LAND)
    axes.add_feature(cartopy.feature.OCEAN)
    axes.add_feature(cartopy.feature.COASTLINE)
    axes.add_feature(cartopy.feature.BORDERS, linestyle='-', alpha=.5)
    axes.add_feature(cartopy.feature.LAKES, alpha=0.95)
    axes.add_feature(cartopy.feature.RIVERS)

ax1 = plt.subplot(1, 1, 1, projection=map_crs)  # create map axes
fancify(ax1)                                    # add some features to map
ax1.set_extent([0, 60, 0, 60], map_crs)         # min/max long and lat

ax1.scatter([22, 11, 31, 30,], [8, 22, 13, 9])  # longitutes , latitudes
plt.show()