Use custom RNG for sketch path #5728

mdboom · 2015-12-23T14:07:28Z

This is an alternative to #5725.

jenshnielsen · 2015-12-23T14:11:37Z

👍 once we can use C++11 I would prefer to use stl random lib but this seems like a suitable solution at the moment

tacaswell · 2015-12-23T14:54:17Z

looks like xkcd tests are failing (as we changed the random number generator).

mdboom · 2015-12-23T14:55:52Z

Ah, of course. I'm not going to try to make it backward compatible, and just update the images :) Honestly, it's probably a good thing -- the C stdlib RNG doesn't guarantee any consistency across compilers anyway, but this should.

jenshnielsen · 2015-12-23T14:57:16Z

The xkcd test have always been failing for me on OSX so that seems likely. Would be great if this fixes that too.

tacaswell · 2015-12-23T14:57:29Z

👍 to not worrying about back compatibility here. I really really hope no one is relying on the details of the sketch path!

tacaswell · 2015-12-23T16:31:50Z

appveyor is not failing when it fails, but this is showing up, it used to just fail on pixel errors.

======================================================================
ERROR: matplotlib.tests.test_path.test_xkcd.test
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Python34_64\envs\test-environment\lib\site-packages\nose\case.py", line 198, in runTest
    self.test(*self.arg)
  File "c:\projects\matplotlib\lib\matplotlib\testing\decorators.py", line 54, in failer
    result = f(*args, **kwargs)
  File "c:\projects\matplotlib\lib\matplotlib\testing\decorators.py", line 232, in do_test
    figure.savefig(actual_fname, **self._savefig_kwarg)
  File "c:\projects\matplotlib\lib\matplotlib\figure.py", line 1698, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "c:\projects\matplotlib\lib\matplotlib\backend_bases.py", line 2230, in print_figure
    **kwargs)
  File "c:\projects\matplotlib\lib\matplotlib\backends\backend_agg.py", line 520, in print_png
    FigureCanvasAgg.draw(self)
  File "c:\projects\matplotlib\lib\matplotlib\backends\backend_agg.py", line 467, in draw
    self.figure.draw(self.renderer)
  File "c:\projects\matplotlib\lib\matplotlib\artist.py", line 62, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "c:\projects\matplotlib\lib\matplotlib\figure.py", line 1230, in draw
    self.patch.draw(renderer)
  File "c:\projects\matplotlib\lib\matplotlib\artist.py", line 62, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "c:\projects\matplotlib\lib\matplotlib\patches.py", line 536, in draw
    renderer.draw_path(gc, tpath, affine, rgbFace)
  File "c:\projects\matplotlib\lib\matplotlib\patheffects.py", line 110, in draw_path
    rgbFace)
  File "c:\projects\matplotlib\lib\matplotlib\patheffects.py", line 211, in draw_path
    Stroke.draw_path(self, renderer, gc, tpath, affine, rgbFace)
  File "c:\projects\matplotlib\lib\matplotlib\patheffects.py", line 200, in draw_path
    renderer.draw_path(gc0, tpath, trans, rgbFace)
  File "c:\projects\matplotlib\lib\matplotlib\backends\backend_agg.py", line 166, in draw_path
    self._renderer.draw_path(gc, path, transform, rgbFace)
OverflowError: In draw_path: Exceeded cell block limit

tacaswell · 2015-12-23T16:32:52Z

ex

FAIL: matplotlib.tests.test_path.test_xkcd.test
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Python34_64\envs\test-environment\lib\site-packages\nose\case.py", line 198, in runTest
    self.test(*self.arg)
  File "c:\projects\matplotlib\lib\matplotlib\testing\decorators.py", line 54, in failer
    result = f(*args, **kwargs)
  File "c:\projects\matplotlib\lib\matplotlib\testing\decorators.py", line 245, in do_test
    '(RMS %(rms).3f)'%err)
matplotlib.testing.exceptions.ImageComparisonFailure: images not close: C:\projects\matplotlib\result_images\test_path\xkcd.png vs. C:\projects\matplotlib\result_images\test_path\xkcd-expected.png (RMS 9.607)

from https://ci.appveyor.com/project/mdboom/matplotlib/build/1.0.338/job/nl9a32g98n9o9rov

tacaswell · 2015-12-26T18:53:48Z

src/path_converters.h

+    double get_double()
+    {
+        m_seed = (a * m_seed + c);
+        return (double)m_seed / (double)(1L << 32);


Is double 32 or 64bits? I wonder if this is what is causing the test failure on windows (in that this is no longer scaled [-1, 1] on all platforms?

double is 64 bits, so it looks to me like this should yield numbers from 0 to (2^32-1)/2^32. I can imagine the result of the division could differ depending on whether it is done using plain double-precision, or using extra-width floating point registers. Use of denormalized numbers is another option. There are compiler switches that can affect floating point results, so the same code on the same hardware can yield different results depending on the compiler and its options. Maybe this is what is happening here?

I think the 1L needs to be 1LL to ensure it is 64 bits.

It should be scaled [0, 1) on all platforms, since the seed is an unsigned int. I think @efiring is right here, that it should be 1LL. Let's try that and run it over the Windows tests.

That would certainly be consistent with a Linux vs. Windows problem. On a 64-bit machine, 1L is 64-bits on Linux and 32-bits on Windows. 1LL is 64 bits on both.

Sorry to spam -- reading further, however, the test failures on Windows are prior to this change, right? That could easily be explained by using the C stdlib RNG which varies entirely from platform to platform. This should (and seemingly does) address that problem by using exactly one RNG implementation everywhere.

Use custom RNG for sketch path

Use custom RNG for sketch path Conflicts: lib/matplotlib/tests/baseline_images/test_path/xkcd.pdf lib/matplotlib/tests/baseline_images/test_path/xkcd.png lib/matplotlib/tests/baseline_images/test_path/xkcd.svg Resolved all by copying binaries from master branch

tacaswell · 2015-12-29T19:52:12Z

backported as 3be4490

Use custom RNG for sketch path

c1c639a

mdboom added this to the Critical bugfix release (1.5.1) milestone Dec 23, 2015

mdboom added the status: needs review label Dec 23, 2015

mdboom added 2 commits December 23, 2015 09:20

Fix constants

9bce658

fix comment

f656043

mdboom added 2 commits December 23, 2015 10:03

Fix sign of seed

b447284

Update test images

de35cc2

tacaswell mentioned this pull request Dec 25, 2015

Windows test failures on appveyor #5748

Closed

tacaswell reviewed Dec 26, 2015
View reviewed changes

Use 1LL to avoid overflow

adafb96

tacaswell added a commit that referenced this pull request Dec 29, 2015

Merge pull request #5728 from mdboom/local-random

1446c69

Use custom RNG for sketch path

tacaswell merged commit 1446c69 into matplotlib:master Dec 29, 2015

tacaswell removed the status: needs review label Dec 29, 2015

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Use custom RNG for sketch path #5728

Use custom RNG for sketch path #5728

mdboom commented Dec 23, 2015

jenshnielsen commented Dec 23, 2015

tacaswell commented Dec 23, 2015

mdboom commented Dec 23, 2015

jenshnielsen commented Dec 23, 2015

tacaswell commented Dec 23, 2015

tacaswell commented Dec 23, 2015

tacaswell commented Dec 23, 2015

tacaswell Dec 26, 2015

efiring Dec 26, 2015

efiring Dec 28, 2015

mdboom Dec 29, 2015

mdboom Dec 29, 2015

mdboom Dec 29, 2015

tacaswell commented Dec 29, 2015

Use custom RNG for sketch path #5728

Use custom RNG for sketch path #5728

Conversation

mdboom commented Dec 23, 2015

jenshnielsen commented Dec 23, 2015

tacaswell commented Dec 23, 2015

mdboom commented Dec 23, 2015

jenshnielsen commented Dec 23, 2015

tacaswell commented Dec 23, 2015

tacaswell commented Dec 23, 2015

tacaswell commented Dec 23, 2015

tacaswell Dec 26, 2015

Choose a reason for hiding this comment

efiring Dec 26, 2015

Choose a reason for hiding this comment

efiring Dec 28, 2015

Choose a reason for hiding this comment

mdboom Dec 29, 2015

Choose a reason for hiding this comment

mdboom Dec 29, 2015

Choose a reason for hiding this comment

mdboom Dec 29, 2015

Choose a reason for hiding this comment

tacaswell commented Dec 29, 2015