telemin telemin - 2 months ago 8
Python Question

Matplotlib and Ipython-notebook: Displaying exactly the figure that will be saved

I am using ipython-notebook a lot at the moment for numerical analysis and plotting of data. In the process of preparing publication quality plots there is a lot of tweaking to get the layout just right, however I can't get ipython/matplotlib to show me what I will be saving in the browser. Making the process more painful than it should be because I have to keep opening the new output file to check it.

Is there a way to get the image that is displayed inline to be the same as the image that is saved?

Example as follows, facecolor='gray' for clarity:

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

fig = plt.figure(figsize=(6,4),facecolor='gray')
ax = fig.add_axes([0.1, 0.1, 0.8, 0.8])
x = np.linspace(0,2*np.pi,1000)
y = np.sin(x)
ax.plot(x,y,label=r'$\sin(x)$')
ax.set_xlim(0,2*np.pi)
ax.set_ylim(-1.2,1.2)
ax.set_xlabel(r'$x$')
ax.set_ylabel(r'$y$')
ax.legend(loc='upper right', frameon=False)
fig.savefig('mypath.png',dpi=300, facecolor='gray')
plt.show()


Note here I have explicity chosen my axes dimensions so that they are equidistant from the two sides of the resulting image. This is respected in the saved image, but ignored in the image shown in the notebook:

Notebook displayed image:

Notebook displayed image

Savefig image:

enter image description here

Answer

As noted by @andrew, the ipython magics are enforcing bbox_inches='tight' by default. This can be overridden using other magics as explained in the ipython documentation:

%matplotlib inline
%config InlineBackend.print_figure_kwargs = {'bbox_inches':None}

produces an inline image identical to that produced by savefig.