python plt.show 关闭
在用python中的matplotlib 画图时，show（）函数总是要放在最后，且它阻止命令继续往下运行，直到1.0.1版本才支持多个show（）的使用。
想在显示图像后继续运行相关的处理命令，或者显示一副图像后关闭它，再显示第二幅图像。如下办法：
plt.close() will close current instance.
plt.close(2) will close figure 2
plt.close(plot1) will close figure with instance plot1
plt.close(‘all’) will close all fiures
Found here.
Remember that plt.show() is a blocking function, so in the example code you used above,plt.close() isn’t being executed until the window is closed, which makes it redundant.
You can use plt.ion() at the beginning of your code to make it non-blocking, although this has other implications.
总结如下例子：
import matplotlib.pyplot as plt
import time
plt.ion() #开启interactive mode
x = np.linspace(0, 50, 1000)
plt.figure(1) # 创建图表1
plt.plot(x, np.sin(x))
plt.draw()
time.sleep(5)
plt.close(1)
plt.figure(2) # 创建图表2
plt.plot(x, np.cos(x))
plt.draw()
time.sleep(5)
print ‘it is ok’
