python - Drawing a graph with NetworkX on a Basemap

Question

I want to plot a graph on a map where the nodes would be defined by coordinates (lat, long) and have some value associated.

I have been able to plot points as a scatterplot on a basemap but can't seem to find how to plot a graph on the map.

Thanks.

EDIT: I have added code on how I plotted the points on a basemap. Most of it has been adapted from code in this article.

from mpl_toolkits.basemap import Basemap
from shapely.geometry import Point, MultiPoint
import pandas as pd
import matplotlib.pyplot as plt

m = Basemap(
        projection='merc',
        ellps = 'WGS84',
        llcrnrlon=-130,
        llcrnrlat=25,
        urcrnrlon=-60,
        urcrnrlat=50,
        lat_ts=0,
        resolution='i',
        suppress_ticks=True)

# Create Point objects in map coordinates from dataframe lon
# and lat values
# I have a dataframe of coordinates
map_points = pd.Series(
                [Point(m(mapped_x, mapped_y)) 
                 for mapped_x, mapped_y in zip(df['lon'],
                                               df['lat'])])
amre_points = MultiPoint(list(map_points.values)) 

plt.clf()
fig = plt.figure()
ax = fig.add_subplot(111, axisbg='w', frame_on=False)
fig.set_size_inches(18.5, 10.5)

# Create a scatterplot on the map
dev = m.scatter(
            [geom.x for geom in map_points],
            [geom.y for geom in map_points],
            20, marker='o', lw=.25,
            facecolor='#33ccff', edgecolor='w',
            alpha=0.9,antialiased=True,
            zorder=3)

m.fillcontinents(color='#555555')

I get this image:

Answer 1

Here is one way to do it:

import networkx as nx
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap as Basemap
m = Basemap(
        projection='merc',
        llcrnrlon=-130,
        llcrnrlat=25,
        urcrnrlon=-60,
        urcrnrlat=50,
        lat_ts=0,
        resolution='i',
        suppress_ticks=True)

# position in decimal lat/lon
lats=[37.96,42.82]
lons=[-121.29,-73.95]
# convert lat and lon to map projection
mx,my=m(lons,lats)

# The NetworkX part
# put map projection coordinates in pos dictionary
G=nx.Graph()
G.add_edge('a','b')
pos={}
pos['a']=(mx[0],my[0])
pos['b']=(mx[1],my[1])
# draw
nx.draw_networkx(G,pos,node_size=200,node_color='blue')

# Now draw the map
m.drawcountries()
m.drawstates()
m.bluemarble()
plt.title('How to get from point a to point b')
plt.show()