How to make IPython notebook matplotlib plot inline

I used %matplotlib inline in the first cell of the notebook and it works. I think you should try:

%matplotlib inline

import matplotlib
import numpy as np
import matplotlib.pyplot as plt

You can also always start all your IPython kernels in inline mode by default by setting the following config options in your config files:

c.IPKernelApp.matplotlib=<CaselessStrEnum>
  Default: None
  Choices: ['auto', 'gtk', 'gtk3', 'inline', 'nbagg', 'notebook', 'osx', 'qt', 'qt4', 'qt5', 'tk', 'wx']
  Configure matplotlib for interactive use with the default matplotlib backend.

If your matplotlib version is above 1.4, it is also possible to use

IPython 3.x and above

%matplotlib notebook

import matplotlib.pyplot as plt

older versions

%matplotlib nbagg

import matplotlib.pyplot as plt

Both will activate the nbagg backend, which enables interactivity.

Ctrl + Enter

%matplotlib inline

Magic Line :D

See: Plotting with Matplotlib.