[ Python 常見問題 ] Writing numerical values on the plot with Matplotlib

Source From Here
Question
Is it possible, with Matplotlib, to print the values of each point on the graph? For example, if I have:

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1. import numpy as np  
2. from matplotlib import pyplot as plt  
3.   
4. x = np.arange(0,10)  
5. y = np.array([5,3,4,2,7,5,4,6,3,2])  
6. plt.plot(x,y)  

How can I display y values on the plot (e.g. print a 5 near the (0,5) point, print a 3 near the (1,3) point, etc.)?

How-To
You can use the annotate command to place text annotations at any x and y values you want. To place them exactly at the data points you could do this:

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1. import numpy as np  
2. from matplotlib import pyplot as plt  
3.   
4. x = np.arange(10)  
5. y = np.array([5,3,4,2,7,5,4,6,3,2])  
6.   
7. fig = plt.figure()  
8. ax = fig.add_subplot(111)  
9. ax.set_ylim(0,10)  
10. plt.plot(x,y)  
11. for i,j in zip(x,y):  
12.     ax.annotate(str(j),xy=(i,j))  
13.   
14. plt.show()  

If you want the annotations offset a little, you could change the annotate line to something like:

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1. ax.annotate(str(j),xy=(i,j+0.5))