Jagged plot in macosx backend

Tony_S_Yu2 · January 12, 2009, 7:59pm

There appears to be a bug in the macosx backend. When I plot large numbers with small variations in the value, the numbers seem to be coarsely rounded off. This bug doesn't appear with other backends (I tried WxAgg and TkAgg). Below is a simple script showing the problem and the resulting plot on the macosx backend.

Thanks,
-Tony

Mac OS X 10.5.6
Matplotlib svn r6779

···

#~~~~~~~~

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 1)
plt.plot(x, x + 1e6)
plt.show()

Michiel_de_Hoon · January 13, 2009, 4:05pm

This is indeed a bug. In some places in the code, I was casting from double to float (which is used by Mac OS X quartz internally) too soon. This created a roundoff error, which shows up as the jagged plot. I am preparing a patch and will submit it as soon as possible.
Thanks for reporting this bug.

--Michiel.

···

--- On Mon, 1/12/09, Tony Yu <tsyu80@...149...> wrote:

From: Tony Yu <tsyu80@...149...>
Subject: [matplotlib-devel] Jagged plot in macosx backend
To: "matplotlib development list" <matplotlib-devel@lists.sourceforge.net>
Date: Monday, January 12, 2009, 2:59 PM
There appears to be a bug in the macosx backend. When I plot
large numbers with small variations in the value, the
numbers seem to be coarsely rounded off. This bug
doesn't appear with other backends (I tried WxAgg and
TkAgg). Below is a simple script showing the problem and the
resulting plot on the macosx backend.

Thanks,
-Tony

Mac OS X 10.5.6
Matplotlib svn r6779

#~~~~~~~~

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 1)
plt.plot(x, x + 1e6)
plt.show()------------------------------------------------------------------------------
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Michiel_de_Hoon · January 16, 2009, 3:59pm

I've written a patch that fixes this bug; see

https://sourceforge.net/tracker/?func=detail&atid=560722&aid=2508440&group_id=80706

--Michiel

···

--- On Mon, 1/12/09, Tony Yu <tsyu80@...149...> wrote:

From: Tony Yu <tsyu80@...149...>
Subject: [matplotlib-devel] Jagged plot in macosx backend
To: "matplotlib development list" <matplotlib-devel@lists.sourceforge.net>
Date: Monday, January 12, 2009, 2:59 PM
There appears to be a bug in the macosx backend. When I plot
large numbers with small variations in the value, the
numbers seem to be coarsely rounded off. This bug
doesn't appear with other backends (I tried WxAgg and
TkAgg). Below is a simple script showing the problem and the
resulting plot on the macosx backend.

Thanks,
-Tony

Mac OS X 10.5.6
Matplotlib svn r6779

#~~~~~~~~

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 1)
plt.plot(x, x + 1e6)
plt.show()------------------------------------------------------------------------------
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Jeff_Whitaker1 · January 16, 2009, 4:13pm

Michiel de Hoon wrote:

I've written a patch that fixes this bug; see

https://sourceforge.net/tracker/?func=detail&atid=560722&aid=2508440&group_id=80706

--Michiel

Just commited your patch (SVN r6787) - thanks Michiel.

-Jeff

···

--- On Mon, 1/12/09, Tony Yu <tsyu80@...149...> wrote:

From: Tony Yu <tsyu80@...149...>
Subject: [matplotlib-devel] Jagged plot in macosx backend
To: "matplotlib development list" <matplotlib-devel@lists.sourceforge.net>
Date: Monday, January 12, 2009, 2:59 PM
There appears to be a bug in the macosx backend. When I plot
large numbers with small variations in the value, the
numbers seem to be coarsely rounded off. This bug
doesn't appear with other backends (I tried WxAgg and
TkAgg). Below is a simple script showing the problem and the
resulting plot on the macosx backend.

Thanks,
-Tony

Mac OS X 10.5.6
Matplotlib svn r6779

#~~~~~~~~

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 1)
plt.plot(x, x + 1e6)
plt.show()------------------------------------------------------------------------------
This SF.net email is sponsored by:
SourcForge Community
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