Preparing data to plot contours in Matplotlib's Basemap

show_map.py

# More Info: http://davydany.com/post/32287214449/matplotlibs-basemap-plotting-a-list-of-latitude
    def show_map(self, a):
 
        # 'a' is of the format [(lats, lons, data), (lats, lons, data)... (lats, lons, data)]
        lats = [ x[0] for x in a ]
        lons = [ x[1] for x in a ]
        data = [ x[2] for x in a ]
         
        lat_min = min(lats)
        lat_max = max(lats)
        lon_min = min(lons)
        lon_max = max(lons)
        data_min = min(data)
        data_max = max(data)
 
        spatial_resolution = 0.5
        fig = plt.figure()
 
        x = np.array(lats)
        y = np.array(lons)
        z = np.array(data)
       
        xinum = (lat_max - lat_min) / spatial_resolution
        yinum = (lon_max - lon_min) / spatial_resolution
        xi = np.linspace(lat_min, lat_max + spatial_resolution, xinum)        # same as [lat_min:spatial_resolution:lat_max] in matlab
        yi = np.linspace(lon_min, lon_max + spatial_resolution, yinum)        # same as [lon_min:spatial_resolution:lon_max] in matlab
        xi, yi = np.meshgrid(xi, yi)
       
        zi = griddata(x, y, z, xi, yi)
       
        m = Basemap(
            projection = 'merc',
            llcrnrlat=lat_min, urcrnrlat=lat_max,
            llcrnrlon=lon_min, urcrnrlon=lon_max,
            rsphere=6371200., resolution='l', area_thresh=10000
        )
       
        m.drawcoastlines()
        m.drawstates()
        m.drawcountries()
       
        lat, lon = m.makegrid(zi.shape[1], zi.shape[0])
        x,y = m(lat, lon)
        m.contourf(x, y, zi)
       
        plt.show()

Very useful, thanks for sharing.

You might need to switch lons and lats for x and y coordinates:

https://gist.github.com/oblakeobjet/7546272

Miha

Very useful work but it would have been more useful to me if you showed how to read in the data, am very very novice to matplotlib and reading all day long to make sense of every small thing.