Uh oh!
There was an error while loading.Please reload this page.
- Notifications
You must be signed in to change notification settings - Fork7.9k
Open
Labels
Milestone
Description
Bug report
Bug summary
When calling Path.arc in a clockwise fashion (theta1 > theta2) , the angle wrapping results in drawing the arc over the opposing angle in a counterclockwise direction.
Code for reproduction
frommatplotlib.pathimportPathimportmatplotlibasmplimportnumpyasnp### Versionprint("MPL Version",mpl.__version__)### Demo the problemtheta1=-1theta2=1path=Path.arc(theta1,theta2)vrt=path.verticesprint(f"Counterclockwise:{len(vrt)} steps.")theta1=1theta2=-1path=Path.arc(theta1,theta2)vrt=path.verticesprint(f"Clockwise:{len(vrt)} steps.")### The following code demonstrates what is happening inside Path.arctheta1=-1.0theta2=1.0## Snippet from matplotlib.path.Path.arceta1=theta1eta2=theta2-360*np.floor((theta2-theta1)/360)# Ensure 2pi range is not flattened to 0 due to floating-point errors,# but don't try to expand existing 0 range.iftheta2!=theta1andeta2<=eta1:eta2+=360print(f"Counterclockwise: Input({theta1},{theta2}), Output({eta1},{eta2})")theta1=1.0theta2=-1.0eta1=theta1eta2=theta2-360*np.floor((theta2-theta1)/360)# Ensure 2pi range is not flattened to 0 due to floating-point errors,# but don't try to expand existing 0 range.iftheta2!=theta1andeta2<=eta1:eta2+=360print(f"Clockwise: Input({theta1},{theta2}), Output({eta1},{eta2})")
Actual outcome
MPL Version 3.0.3Counterclockwise: 7 steps.Clockwise: 49 steps.Counterclockwise: Input(-1.0, 1.0), Output(-1.0, 1.0)Clockwise: Input(1.0, -1.0), Output(1.0, 359.0)Expected outcome
The direction of the arc should not matter, either direction should draw an arc that covers 2 degrees, and the vertices generated by the function should go in the direction chosen by the user.
Proposed fix
For my purposes I fixed the problem by adding another condition into the angle wrapping logic.
eta1=theta1eta2=theta2-360*np.floor((theta2-theta1)/360)# Ensure 2pi range is not flattened to 0 due to floating-point errors,# but don't try to expand existing 0 range.iftheta2!=theta1andeta2<=eta1:eta2+=360# This is the new logiciftheta1>theta2:eta1+=360eta1,eta2=np.deg2rad([eta1,eta2])
This assures that directionality is kept and the correct angle is covered.
Matplotlib version
Probably irrelevant but:
- Operating system: Windows
- Matplotlib version: 3.0.3 (conda)
- Python version: 3.7.0 (conda)