在Geopandas中地图周围的边距问题

Question

我似乎无法解决GeoPandas地图和添加的注释之间的某些边距/位置问题。注释是通过函数addChartSignature和addTitle添加的，它们引起了可怕的布局。

我设法用hack整理了一些垂直边距问题，请参见评论### to deal with vertical margin issue，但是我似乎无法处理左侧的边距：我想要地图，签名和标题与左侧对齐，并且边距很小（如右侧）。

我添加了变量righthspace以使注释正确移动，但是它无济于事，反正感觉也不对。

下面的代码示例总结了问题

from __future__ import division

import matplotlib.pyplot as plt
import geopandas
from mpl_toolkits.axes_grid1 import make_axes_locatable

def addChartSignature(ax, vspace=0, righthspace=0):

    ax.annotate('', 
                xy=(0.97, 0.05 + vspace), 
                xycoords='figure fraction',
                xytext=(0.03 + righthspace,0.05 + vspace), 
                textcoords='figure fraction',
                arrowprops=dict(arrowstyle="-",
                                linewidth=0.7,
                                facecolor='grey', 
                                alpha=.7, 
                                edgecolor='grey'),
                horizontalalignment = 'center', 
                verticalalignment='bottom')

    ax.annotate(u" ©myCompany", 
                 xy=(0.5, 0.5), 
                 xycoords='figure fraction',
                 xytext= (0.03 + righthspace,0.01+vspace), 
                 textcoords='figure fraction',
                 ha="left", 
                 va="bottom", 
                 color = 'grey', 
                 alpha = .7, 
                 fontsize = 11)

    ax.annotate(u"Source: Internal", 
                 xy=(0.5, 0.5), 
                 xycoords='figure fraction',
                 xytext=(0.97,0.01+vspace), 
                 textcoords='figure fraction',
                 ha="right", 
                 va="bottom", 
                 color = 'grey', 
                 alpha = .7, 
                 fontsize = 11)

def addTitle(ax, vspace=0, righthspace=0):
    ax.annotate("My Chart Title", 
                 xy=(0.5, 0.5), 
                 xycoords='figure fraction',
                 xytext=(0.01+righthspace, 0.985+vspace), 
                 textcoords='figure fraction',
                 ha="left", 
                 va="top", 
                 color = 'black', 
                 alpha = .75, 
                 fontsize = 19, 
                 weight = 'bold')

path = geopandas.datasets.get_path('naturalearth_lowres')
world = geopandas.read_file(path)
world = world[(world.pop_est>0) & (world.name!="Antarctica")]    

plt.style.use('fivethirtyeight')
fig = plt.figure(figsize=(8, 6))
ax = fig.add_axes([0., 0., 1, 1])

ax = world.plot(color="lightgrey", ax=ax)
divider = make_axes_locatable(ax)
cax = divider.append_axes('right',  size="3%", pad=-1.3) 
world.dropna().plot(
        column='pop_est', 
        ax=ax, 
        legend=True, 
        cax=cax, 
        cmap='RdYlGn',
        )

ax.grid(color='#F8F8F8')
ax.set_xticklabels([])
ax.set_yticklabels([])

### to deal with vertical margin issue
ax.set_aspect(aspect=4./3)
ax.margins(0)
ax.apply_aspect()
bbox = ax.get_window_extent().inverse_transformed(fig.transFigure)
w,h = fig.get_size_inches()
fig.set_size_inches(w*bbox.width, h*bbox.height)

addChartSignature(ax, righthspace = 0.05)
addTitle(ax, righthspace = 0.05)