python - scatter plot data does not appear on continents in 'hammer' basemap

Question

I am attempting to plot a dataset over the 'hammer' basemap using a scatter plot. However, the data points won't plot on top of the continents. I noticed in the matplotlib example, there is also not data on the continents (I assumed this was due to the nature of the example). I'm wondering if I'm doing something wrong, or if data cannot be plotted on top of the continents using 'hammer' by design.

If this is the case, is there an ideal basemap to use to plot scatter plot data over the whole Earth (using a relief map would be great, but I would settle for anything at this point)?

Answer 1

You're probably missing the keyword to interpret lat-lon data as such. From the help for Basemap.scatter:

If latlon keyword is set to True, x,y are intrepreted as longitude and latitude in degrees. Data and longitudes are automatically shifted to match map projection region for cylindrical and pseudocylindrical projections, and x,y are transformed to map projection coordinates. If latlon is False (default), x and y are assumed to be map projection coordinates.

I also needed to increase the z-order to get scatter on top of the continents as well as the oceans.

import time, calendar, datetime, numpy
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
# draw map with markers for float locations
m = Basemap(projection='hammer',lon_0=180)
m.drawmapboundary(fill_color='#99ffff')
m.fillcontinents(color='#cc9966',lake_color='#99ffff')

m.scatter([-73.98, 238., 0.08, 0., 116.38],[40.78,47.6,  51.53,0., 39.91],
          latlon=True, # Ta-da!
          marker='o',color='k',
          zorder=10)

plt.title('Hammer projection, data on top',fontsize=12)
plt.show()