【Python】世界地図・その右と下にグラフを描く

論文用の画像を作るためのテンプレートのメモ．
真ん中：世界地図，右と下：緯度・経度ごとの陸地面積．

若干枠線がズレるのはなぜ？

map_right_bottom.py

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

north, south, dlat = 90.0, -60.0, 30.0
east , west , dlon = 180.0, -180.0, 60.0

def gen_axes(figWidth=10.0, rightWidth=4.0, bottomHeight=2.5):
    '''
    center|right
    ------
    bottom
    '''
    centerWidth  = figWidth - rightWidth
    centerHeight = centerWidth * (north - south) / (east - west)
    figHeight    = centerHeight + bottomHeight
    fig = plt.figure(figsize=(figWidth, figHeight))
    gs = GridSpec(2, 2,
                  width_ratios=(centerWidth,rightWidth), height_ratios=(centerHeight,bottomHeight),
                  wspace=0.0, hspace=0.0)
    return [plt.subplot(gs[0,0]), plt.subplot(gs[0,1]), plt.subplot(gs[1,0])] # center, right, bottom

def center_map(ax):
    m = Basemap(llcrnrlon=west, llcrnrlat=south, urcrnrlon=east, urcrnrlat=north, ax=ax)
    m.drawcoastlines(linewidth=.4)
    m.fillcontinents(color='0.7')
    m.drawparallels(np.arange(south+dlat,north,dlat), labels=[1,0,0,0])
    m.drawmeridians(np.arange(west +dlon,east ,dlon), labels=[0,0,1,0])
    return

def right_plot(ax, data):
    ax.plot(data, np.arange(len(data))[::-1])
    left, right = ax.get_xlim()
    left        = 0
    ax.set_xlim(left=left, right=right)
    ax.hlines(y=range(120, 720, 120), xmin=left, xmax=right, linestyles=':', linewidth=1.0)
    ax.set_ylim(0, len(data))
    ax.tick_params(left=False, right=False)
    ax.tick_params(labelleft=False, labelright=False)
    return

def bottom_plot(ax, data):
    ax.plot(data)
    ax.set_xlim(0, len(data))
    bottom, top = ax.get_ylim()
    bottom      = 0
    ax.set_ylim(top=top, bottom=bottom)
    ax.vlines(x=range(240, 1440, 240), ymin=bottom, ymax=top, linestyles=':', linewidth=1.0)
    ax.tick_params(top=False, bottom=False)
    ax.tick_params(labeltop=False, labelbottom=False)
    ax.set_facecolor((0.0, 0.0, 0.0, 0.0))


def main(*args):
    landMap = # グリッドごとの陸地面積マップ
    landMap = np.ma.masked_less_equal(landMap, 0.0)
    landLat = landMap.sum(axis=1)
    landLon = landMap.sum(axis=0)

    axs = gen_axes()

    center_map (axs[0])
    right_plot (axs[1], landLat)
    bottom_plot(axs[2], landLon)

    plt.show()