zorder of drawmapboundary() gets on top of imshow() #474

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap

def plotBmap(data, x, y, ax, order):

    bmap=Basemap(projection='cyl',\
            llcrnrlat=y[0],llcrnrlon=x[0],\
            urcrnrlat=y[-1],urcrnrlon=x[-1],\
            ax=ax)

    bmap.imshow(data, interpolation='nearest')

    # plot axes labels
    lat_labels=np.linspace(-90, 90, 5)
    lon_labels=np.linspace(0, 360, 6)
    ax.set_yticks(lat_labels)
    ax.set_xticks(lon_labels)
    ax.tick_params(axis='both',which='major',labelsize=10)
    ax.xaxis.set_ticklabels([])
    ax.yaxis.set_ticklabels([])

    # draw continents
    bmap.drawcoastlines(linewidth=1.5,linestyle='solid',color='k',\
        antialiased=True)
    bmap.drawcountries(linewidth=0.5,linestyle='solid',color='k',\
            antialiased=True)

    if order=='before':
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8')
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
    elif order=='after':
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8')

    return bmap

if __name__=='__main__':

    x=np.arange(0, 361, 1)     # lon
    y=np.arange(-90, 91, 1)    # lat
    X,Y=np.meshgrid(x,y)
    z=np.sin(X/90.)+np.cos(Y/90.)

    # create an area of missings
    z[10:50, 20:80]=np.nan

    fig, (ax1, ax2)=plt.subplots(1, 2, figsize=(12,6))

    bmap1=plotBmap(z, x, y, ax1, 'before')
    ax1.set_title('before')

    bmap2=plotBmap(z, x, y, ax2, 'after')
    ax2.set_title('after')

    fig.show()