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From b..@apache.org
Subject zeppelin git commit: ZEPPELIN-1318 - Add support for matplotlib displaying png images in python interpreter
Date Sun, 14 Aug 2016 02:28:45 GMT
Repository: zeppelin
Updated Branches:
  refs/heads/master 100b97821 -> 8b40268d1

ZEPPELIN-1318 - Add support for matplotlib displaying png images in python interpreter

### What is this PR for?
This PR adds support for plotting png images using the matplotlib helper function within a
python interpreter (eg `z.show()`). The primary motivation for this is due to the overhead
incurred from svg images, which can lag the notebooks if multiple, complicated images are
generated (for example, multiple filled contour plots). png images are more lightweight, but
of course come at a cost of image quality due to them being raster rather than vector like
svg. The support for png images is incorporated through the use of a new optional argument
to `z.show` called `fmt` which can be one of `'svg'` or `'png'`. The same code that is currently
used in show is used for svg images while the code for png images relies on converting the
image directly to a byte array and then entering the decoded byte string directly into an
HTML image tag. Currently `fmt` defaults to `'png'` but I think we should consider discussing
the pros and cons of each option in this PR.

### What type of PR is it?

### What is the Jira issue?

### How should this be tested?
In a notebook cell, enter:
import matplotlib.pyplot as plt
import numpy as np

z.show(plt, fmt=fmt)
Where `fmt` may be one of `'svg'` or `'png'`, and any other input should result in a `ValueError`.
I would also recommend testing the example in the screenshot below.

### Screenshots (if appropriate)
![zeppelin plot](https://puu.sh/qzc4t/b8fcfe856e.png)

### Questions:
* Does the licenses files need update? No
* Is there breaking changes for older versions? No
* Does this needs documentation? Yes (if the changes to the `help()` docstring are not sufficient)

Author: Alex Goodman <agoodm@users.noreply.github.com>

Closes #1329 from agoodm/ZEPPELIN-1318 and squashes the following commits:

2e9ce4c [Alex Goodman] Update python.md
1efa0c9 [Alex Goodman] ZEPPELIN-1318 - Add support for png images in z.show()

Project: http://git-wip-us.apache.org/repos/asf/zeppelin/repo
Commit: http://git-wip-us.apache.org/repos/asf/zeppelin/commit/8b40268d
Tree: http://git-wip-us.apache.org/repos/asf/zeppelin/tree/8b40268d
Diff: http://git-wip-us.apache.org/repos/asf/zeppelin/diff/8b40268d

Branch: refs/heads/master
Commit: 8b40268d1665f9b5238fb1ee15846f25de8d1634
Parents: 100b978
Author: Alex Goodman <agoodm@users.noreply.github.com>
Authored: Fri Aug 12 21:42:48 2016 -0700
Committer: Alexander Bezzubov <bzz@apache.org>
Committed: Sun Aug 14 11:28:38 2016 +0900

 docs/interpreter/python.md             |  6 +++---
 python/src/main/resources/bootstrap.py | 24 ++++++++++++++++++------
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/docs/interpreter/python.md b/docs/interpreter/python.md
index dc10a75..4aa3468 100644
--- a/docs/interpreter/python.md
+++ b/docs/interpreter/python.md
@@ -87,7 +87,7 @@ print("".join(z.checkbox("f3", [("o1","1"), ("o2","2")],["1"])))
 ## Matplotlib integration
  The python interpreter can display matplotlib graph with the function `z.show()`.
- You need to have matplotlib module installed and a XServer running to use this functionality
+ You need to have matplotlib module installed and a XServer running to use this functionality!
@@ -97,12 +97,12 @@ plt.figure()
-z.show function can take optional parameters to adapt graph width and height
+The `z.show()` function can take optional parameters to adapt graph dimensions (width and
height) as well as output format (png or optionally svg).
 z.show(plt, width='50px')
-z.show(plt, height='150px')
+z.show(plt, height='150px', fmt='svg')
 <img class="img-responsive" src="../assets/themes/zeppelin/img/docs-img/pythonMatplotlib.png"

diff --git a/python/src/main/resources/bootstrap.py b/python/src/main/resources/bootstrap.py
index 889b456..9e93839 100644
--- a/python/src/main/resources/bootstrap.py
+++ b/python/src/main/resources/bootstrap.py
@@ -19,6 +19,7 @@
 # Remove interactive mode displayhook
 import sys
 import signal
+import base64
     import StringIO as io
@@ -69,10 +70,10 @@ def help():
  <div><br/> z.show function can take optional parameters
- to adapt graph width and height</div>
+ to adapt graph dimensions (width and height) and format (png or svg)</div>
  <div><b>example </b>:
- z.show(plt,height='150px') </pre></div>
+ z.show(plt,height='150px', fmt='svg') </pre></div>
  <h3>Pandas DataFrame</h3>
  <div> You need to have Pandas module installed
@@ -163,13 +164,24 @@ class PyZeppelinContext(object):
         body_buf.close(); header_buf.close()
-    def show_matplotlib(self, p, width="100%", height="100%", **kwargs):
+    def show_matplotlib(self, p, width="100%", height="100%",
+                        fmt='png', **kwargs):
         """Matplotlib show function
         img = io.StringIO()
-        p.savefig(img, format="svg")
-        html = "%html <div style='width:{width};height:{height}'>{image}<div>"
-        print(html.format(width=width, height=height, image=img.getvalue()))
+        if fmt == 'png':
+            p.savefig(img, format=fmt)
+            html = "%html <img src={img} width={width}, height={height}>"
+            img_str = "data:image/png;base64,"
+            img_str += base64.b64encode(img.getvalue().strip())
+        elif fmt == 'svg':
+            p.savefig(img, format=fmt)
+            html = "%html <div style='width:{width};height:{height}'>{img}<div>"
+            img_str = img.getvalue()
+        else:
+            raise ValueError("fmt must be 'png' or 'svg'")
+        print(html.format(width=width, height=height, img=img_str))

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