Python怎么利用matplotlib生成图片背景及图例透明

# coding=utf-8 

# matplotlib背景透明示例图 

# python 3.5 

importnumpy as np 

importmatplotlib.pyplot as plt 

frompylabimportmpl 

importscipy.stats as stats 

# 设置中文字体 

mpl.rcParams['font.sans-serif']=['SimHei']

defautolabel(rects): 

 # attach some text labels 

 forrectinrects: 

  height=rect.get_height() 

  # 设置标注文字及位置 

  ax.text(rect.get_x()+rect.get_width()/2,0.03+height,'%.4f'%height, ha='center', va='bottom') 

# 数据 

testData=[[0.87,0.40,0.56], 

   [0.97,0.50,0.33], 

   [0.88,0.30,0.44], 

   [0.25,0.23,0.17], 

   [0.73,0.33,0.45]] 

N=3 

width=0.5 

ind=np.arange(width, width*6*N, width*6) 

fig, ax=plt.subplots() 

rectsTest1=ax.bar(ind, (testData[0][0], testData[0][1], testData[0][2]), width, color=(0,0,1,1), edgecolor=(0,0,1,1)) 

rectsTest2=ax.bar(ind+width, (testData[1][0], testData[1][1], testData[1][2]), width, color=(1,0,0,1), edgecolor=(1,0,0,1)) 

rectsTest3=ax.bar(ind+2*width, (testData[2][0], testData[2][1], testData[2][2]), width, color=(0,1,0,1), edgecolor=(0,1,0,1)) 

rectsTest4=ax.bar(ind+3*width, (testData[3][0], testData[3][1], testData[3][2]), width, color=(1,0.6471,0,1), edgecolor=(1,0.6471,0,1)) 

rectsTest5=ax.bar(ind+4*width, (testData[4][0], testData[4][1], testData[4][2]), width, color=(0.5804,0,0.8275,1), edgecolor=(0.5804,0,0.8275,1)) 

ax.set_xlim(0,9.5) 

ax.set_ylim(0,1.4) 

ax.set_ylabel('数值') 

ax.yaxis.grid(True) 

ax.set_xticks(ind+width*2.5) 

ax.set_xticklabels(('P','R','F')) 

# 设置图例 

legend=ax.legend((rectsTest1, rectsTest2, rectsTest3, rectsTest4, rectsTest5), ('test1','test2','test3','test4','test5')) 

frame=legend.get_frame() 

frame.set_alpha(1) 

frame.set_facecolor('none')# 设置图例legend背景透明 

# 给每个数据矩形标注数值 

autolabel(rectsTest1) 

autolabel(rectsTest2) 

autolabel(rectsTest3) 

autolabel(rectsTest4) 

autolabel(rectsTest5) 

plt.savefig('C:/Users/XX/Desktop/test.png',format='png', bbox_inches='tight', transparent=True, dpi=600)# bbox_inches='tight'