anomalous line segment in path rendering

To visualize trees, I'm creating Path objects that draw horizontal and
vertical lines between connected nodes. I make sure to end these
paths with a MOVETO code and the final vertex, and a STOP code and the
final vertex. But I consistently see an anomalous line segment
getting rendered, angling between two disconnected nodes. The problem
is intermittent - if I pan or zoom, the anomalous segment might go
away or change position. It's also consistent - if I create two plots
of the same tree structure, the anomalous segment appears in the same
way. I've tried different backends, all the same. The attached
screenshots illustrate the problem. In each case, a detail of the
tree is shown in the right pane. path-artefact.png shows the
anomalous segment angling across the view. Any ideas on why this
occurs? I'm using the latest matplotlib release.

Thanks
-Rick

path.png

path-artefact.png

To visualize trees, I'm creating Path objects that draw horizontal and
vertical lines between connected nodes. I make sure to end these
paths with a MOVETO code and the final vertex, and a STOP code and the
final vertex. But I consistently see an anomalous line segment
getting rendered, angling between two disconnected nodes. The problem
is intermittent - if I pan or zoom, the anomalous segment might go
away or change position. It's also consistent - if I create two plots
of the same tree structure, the anomalous segment appears in the same
way. I've tried different backends, all the same. The attached
screenshots illustrate the problem. In each case, a detail of the
tree is shown in the right pane. path-artefact.png shows the
anomalous segment angling across the view. Any ideas on why this
occurs? I'm using the latest matplotlib release.

Does it still happen if you turn off path simplification? E.g.

rcParams['path.simplify'] = False

Eric

···

On 05/28/2010 06:31 AM, Richard Ree wrote:

Thanks
-Rick

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To visualize trees, I'm creating Path objects that draw horizontal and
vertical lines between connected nodes. I make sure to end these
paths with a MOVETO code and the final vertex, and a STOP code and the
final vertex. But I consistently see an anomalous line segment
getting rendered, angling between two disconnected nodes. The problem
is intermittent - if I pan or zoom, the anomalous segment might go
away or change position. It's also consistent - if I create two plots
of the same tree structure, the anomalous segment appears in the same
way. I've tried different backends, all the same. The attached
screenshots illustrate the problem. In each case, a detail of the
tree is shown in the right pane. path-artefact.png shows the
anomalous segment angling across the view. Any ideas on why this
occurs? I'm using the latest matplotlib release.

Does it still happen if you turn off path simplification? E.g.

rcParams['path.simplify'] = False

Yes, this seems to fix it. Thanks!

-Rick

···

On Fri, May 28, 2010 at 12:02 PM, Eric Firing wrote:

On 05/28/2010 06:31 AM, Richard Ree wrote:

Eric

Thanks
-Rick

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Good. I think this is one of the path simplification problems that has already been fixed in svn by Mike D. If you can build from svn and try your program without turning path simplification off, then we could be sure.

Eric

···

On 05/28/2010 09:10 AM, Richard Ree wrote:

On Fri, May 28, 2010 at 12:02 PM, Eric Firing wrote:

On 05/28/2010 06:31 AM, Richard Ree wrote:

To visualize trees, I'm creating Path objects that draw horizontal and
vertical lines between connected nodes. I make sure to end these
paths with a MOVETO code and the final vertex, and a STOP code and the
final vertex. But I consistently see an anomalous line segment
getting rendered, angling between two disconnected nodes. The problem
is intermittent - if I pan or zoom, the anomalous segment might go
away or change position. It's also consistent - if I create two plots
of the same tree structure, the anomalous segment appears in the same
way. I've tried different backends, all the same. The attached
screenshots illustrate the problem. In each case, a detail of the
tree is shown in the right pane. path-artefact.png shows the
anomalous segment angling across the view. Any ideas on why this
occurs? I'm using the latest matplotlib release.

Does it still happen if you turn off path simplification? E.g.

rcParams['path.simplify'] = False

Yes, this seems to fix it. Thanks!

-Rick