Output Error while generating large number of fine slices about gdspy

[heitzmann]

Which version of gdspy are you using? I'm guessing 1.2 or latter, because this looks like a precision error.
slice has a keyword argument precision that is set to 0.001 by default, which means all polygon vertices are aligned to a grid with 1e-3 spacing.

Try to run with:

result = gdspy.slice(polylist, (sl), 0, precision=1e-6)

to see if that solves the problem.

[srikanth1986]

Yes, That fixes it. I wasn't sure what the precision parameter was for. Maybe you can add that to the description here http://gdspy.readthedocs.io/en/latest/geometry.html#slice And thanks for the super quick reply!

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On Thu, Dec 28, 2017 at 5:29 PM, Lucas H. Gabrielli < ***@***.***> wrote: Which version of gdspy are you using? I'm guessing 1.2 or latter, because this looks like a precision error. slice has a keyword argument precision that is set to 0.001 by default, which means all polygon vertices are aligned to a grid with 1e-3 spacing. Try to run with: result = gdspy.slice(polylist, (sl), 0, precision=1e-6) to see if that solves the problem. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#36 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB7T5bs-X9PyuW3owFWhVlkvI_pWkaajks5tE4KKgaJpZM4ROPnG> .

[heitzmann]

Thanks! I missed that in the docs! Fixed in 5ca48f0.

[srikanth1986]

Although this has fixed the problem for me, I do have some concern about this solution. One, I was slicing at 0.01 intervals while the default precision was 0.001. The second being that, what you say should have resulted in an abrupt shift like a step function, but if you look at the right half of the images, the slices catch up with original in a rather smooth curve. Also I noticed the same thing happening in rectangles half as long as this where the slices at the left and right are aligned while those in the middle are not. Grid snapping doesn't explain this in my opinion.

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On Thu, Dec 28, 2017 at 5:40 PM, Lucas H. Gabrielli < ***@***.***> wrote: Thanks! I missed that in the docs! Fixed in 5ca48f0 <5ca48f0> . — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#36 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB7T5THWr0gLS55fvIX5N-YGqTOT5oYQks5tE4UygaJpZM4ROPnG> .

[heitzmann]

Indeed... that is an artifact of the combined effects of the grid snapping and the way slicing is performed: from left to right, one slice at a time.
To solve the issue I believe the _chop function in the C-extension should perform all chops (from the list of positions in a single run).
I'll reopen the issue until this can be implemented.

[heitzmann]

@srikanth1986 I believe changes in af0cbf3 solve this issue. I've tested your example and it works as expected for any precision setting.
Please let me know if you find any other issue.

(update: correct commit)

[srikanth1986]

Hi Lucas, How do I get this update for python on windows? I tried both pip install --upgrade gdspy and then downloaded the files and ran python setup.py install I still see the old output.

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On Fri, Dec 29, 2017 at 10:13 PM, Lucas H. Gabrielli < ***@***.***> wrote: @srikanth1986 <https://github.com/srikanth1986> I believe changes in 9a951ae <9a951ae> solve this issue. I've tested your example and it works as expected for any precision setting. Please let me know if you find any other issue. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#36 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB7T5XBYVovr9veJOyeKL4Zmg048UkThks5tFRaWgaJpZM4ROPnG> .

[heitzmann]

@srikanth1986 You can get the latest Windows builds from AppVeyor: https://ci.appveyor.com/project/heitzmann/gdspy
Just select the environment corresponding to your python version and platform, then go to the Artifacts tab and download the whl file.

[srikanth1986]

That works. Thank you very much!

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On Tue, Jan 2, 2018 at 3:36 PM, Lucas H. Gabrielli ***@***.*** > wrote: @srikanth1986 <https://github.com/srikanth1986> You can get the latest Windows builds from AppVeyor: https://ci.appveyor.com/projec t/heitzmann/gdspy Just select the environment corresponding to your python version and platform, then go to the Artifacts tab and download the whl file. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#36 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB7T5XWlbNNnJxwcJseSo0dpns_jV7zCks5tGf-zgaJpZM4ROPnG> .