rasterizer.py 文件源码

def basemap_barbs_mercator(u,v,lat,lon):

    # lon/lat extents
    lons = (np.amin(lon), np.amax(lon))
    lats = (np.amin(lat), np.amax(lat))

    # construct spherical mercator projection for region of interest
    m = Basemap(projection='merc',llcrnrlat=lats[0], urcrnrlat=lats[1],
                llcrnrlon=lons[0],urcrnrlon=lons[1])

    #vmin,vmax = np.nanmin(grid),np.nanmax(grid)
    fig = plt.figure(frameon=False,figsize=(12,8),dpi=72*4)
    plt.axis('off')
    m.quiver(lon,lat,u,v,latlon=True)

    str_io = StringIO.StringIO()
    plt.savefig(str_io,bbox_inches='tight',format='png',pad_inches=0,transparent=True)
    plt.close()

    numpy_bounds = [ (lons[0],lats[0]),(lons[1],lats[0]),(lons[1],lats[1]),(lons[0],lats[1]) ]
    float_bounds = [ (float(x), float(y)) for x,y in numpy_bounds ]
    return str_io.getvalue(), float_bounds