Imbed matplotlib figure into iPython HTML

Question

I want to dynamically write and display HTML with a code cell in Jupyter Notebook. The objective is to generate the HTML to display table, div, img tags in some way I choose. I want to capture img data and place it where I want in this auto generated HTML.

So far I've figured out that I can do the following:

from IPython.core.display import HTML

HTML("<h1>Hello</h1>")

and get:

Hello

That's great. However, I want to be able to do this:

HTML("<h1>Hello</h1><hr/><img src='somestring'/>")

and get something similar to a Hello with a horizontal line and an image below it, where the image is the same one as below.

import pandas as pd
import numpy as np

np.random.seed(314)
df = pd.DataFrame(np.random.randn(1000, 2), columns=['x', 'y'])

df.plot.scatter(0, 1)

The result should look like this:

Question

What do I replace 'something' with in order to implement this? And more to the point, how do I get it via python?

I would have imagined there was an attribute on a figure object that would hold an serialized version of the image but I can't find it.

Answer 1

After some digging around. Credit to Dmitry B. for pointing me in the right direction.

Solution

from IPython.core.display import HTML
import binascii
from StringIO import StringIO
import matplotlib.pyplot as plt

# open IO object
sio = StringIO()

# generate random DataFrame
np.random.seed(314)
df = pd.DataFrame(np.random.randn(1000, 2), columns=['x', 'y'])

# initialize figure and axis
fig, ax = plt.subplots(1, 1)

# plot DataFrame
ax.scatter(df.iloc[:, 0], df.iloc[:, 1]);

# print raw canvas data to IO object
fig.canvas.print_png(sio)

# convert raw binary data to base64
# I use this to embed in an img tag
img_data = binascii.b2a_base64(sio.getvalue())

# keep img tag outter html in its own variable
img_html = '<img src="data:image/png;base64,{}&#10;">'.format(img_data)

HTML("<h1>Hello</h1><hr/>"+img_html)

I end up with:

Answer 2

from IPython.core.display import Image
import io

s = io.BytesIO()

# make your figure here

plt.savefig(s, format='png', bbox_inches="tight")
plt.close()

Image(s.getvalue())