Matplotlib-Basemap：如何在轴外隐藏文本？

Question

我想在轴外隐藏文本，仅显示其中的内容。我曾尝试使用zorder来做到这一点，但只是轴上的文本消失了！

import pandas as pd
import numpy as np
import numpy.ma as ma
import matplotlib.pyplot as plt
from matplotlib import cm as CM
from mpl_toolkits.basemap import Basemap
from matplotlib.patches import Polygon

names=['stat','latd', 'longd', 'AQI', 'Grade', 'PM25', 'PM10', 'CO', 'NO2', 'O3', 'O3_8h', 'SO2']
cities=pd.read_table('2013061713.000',sep='\s+',names=names,skiprows=[0],na_values=[9999])
namesa=['LOC1','LOC2','LOC3','LOC4','LOC5','LOC6','LOC7','LOC8']
LOC=pd.read_table('loc/location_use13-06-17.txt',sep='\s+',names=namesa,na_values=[9999])
# Extract the data we're interested in
lat = cities['latd'].values
lon = cities['longd'].values
pm25 = cities['PM25'].values
aqi = cities['AQI'].values
pm25_max=np.nanmax(pm25)
pm25_min=np.nanmin(pm25)
latmax=LOC.iloc[:,:4].max().max()
latmin=LOC.iloc[:,:4].min().min()
lonmax=LOC.iloc[:,4:8].max().max()
lonmin=LOC.iloc[:,4:8].min().min()
llcrnrlon=lonmin-0.5
llcrnrlat=latmin-0.5
urcrnrlon=lonmax+0.5
urcrnrlat=latmax+0.5
fig = plt.figure(figsize=(8, 8))
m = Basemap(llcrnrlon=llcrnrlon,llcrnrlat=llcrnrlat,urcrnrlon=urcrnrlon,urcrnrlat=urcrnrlat, epsg=4269)
m.shadedrelief()
m.drawparallels(np.arange(20.,40,2.5),linewidth=1, dashes=[4, 2], labels=[1,0,0,0], color= 'gray',zorder=0, fontsize=10)
m.drawmeridians(np.arange(100.,125.,2.),linewidth=1, dashes=[4, 2], labels=[0,0,0,1], color= 'gray',zorder=0, fontsize=10)
y_offset    = 0.05
rotation    = 30
x, y = m(lon, lat)
for i,j,k,a in zip(x[::2],y[::2],pm25[::2],aqi[::2]):
    m.scatter(i, j,c=k, s=a, cmap=CM.get_cmap('tab20b',20), alpha=0.5)
    plt.text(i, j+y_offset, k,rotation=rotation,fontsize=6,color='w')
for i,j,k,a in zip(x[1::2],y[1::2],pm25[1::2],aqi[1::2]):
    m.scatter(i, j,c=k, s=a, cmap=CM.get_cmap('tab20b',20), alpha=0.5)
    plt.text(i, j-y_offset, k,rotation=rotation,fontsize=6,color='b')
plt.savefig('PM25_showtext130617.png',dpi=600)
plt.show()

这是所有文字的图片，文字应隐藏在轴上：

这是我使用zorder时的当前输出，这与我尝试实现的结果相反：

plt.text(i, j+y_offset, k,rotation=rotation,fontsize=6,color='w',zorder=-1000)