How to show matplotlib plots?

Question

I am sure the configuration of matplotlib for python is correct since I have used it to plot some figures.

But today it just stop working for some reason. I tested it with really simple code like:

import matplotlib.pyplot as plt
import numpy as np
x = np.arange(0, 5, 0.1)
y = np.sin(x)
plt.plot(x, y)

There's no error but just no figure shown up.

I am using python 2.6, Eclipse in Ubuntu

Answer 1

In matplotlib you have two main options:

1. Create your plots and draw them at the end:

   import matplotlib.pyplot as plt
   
   plt.plot(x, y)
   plt.plot(z, t)
   plt.show()
   

2. Create your plots and draw them as soon as they are created:

   import matplotlib.pyplot as plt
   from matplotlib import interactive
   interactive(True)
   
   plt.plot(x, y)
   raw_input('press return to continue')
   
   plt.plot(z, t)
   raw_input('press return to end')
   

Answer 2

You must use plt.show() at the end in order to see the plot

Answer 3

In case anyone else ends up here using Jupyter Notebooks, you just need

%matplotlib inline

Purpose of "%matplotlib inline"

Answer 4

Save the plot as png

plt.savefig("temp.png")

Answer 5

plt.plot(X,y) function just draws the plot on the canvas. In order to view the plot, you have to specify plt.show() after plt.plot(X,y). So,

import matplotlib.pyplot as plt
X = //your x
y = //your y
plt.plot(X,y)
plt.show()

Answer 6

You have to use show() methode when you done all initialisations in your code in order to see the complet version of plot:

import matplotlib.pyplot as plt

plt.plot(x, y)
................
................
plot.show()