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Vector #22435

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9d939f7
add Axes.vector
Feb 7, 2022
3ba7615
Merge branch 'matplotlib:main' into vector
kmdalton Feb 8, 2022
4371b2f
fix whitespace for flake8
Feb 9, 2022
021b62d
Merge branch 'matplotlib:main' into vector
kmdalton Feb 9, 2022
7f8eeb8
Merge branch 'vector' of ssh://github.com/kmdalton/matplotlib into ve…
Feb 9, 2022
c82b32e
fixed docstring indentation
Feb 9, 2022
2fdae0b
update vector signature
ianhi Jan 25, 2023
acbfee7
add set/get delta to FancyArrowPatch
ianhi Jan 25, 2023
91d7e51
fix: small bugfixes to vector logic
ianhi Jan 25, 2023
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39 changes: 39 additions & 0 deletions lib/matplotlib/axes/_axes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6777,6 +6777,45 @@ def hist(self, x, bins=None, range=None, density=False, weights=None,
else "list[Polygon]")
return tops, bins, cbook.silent_list(patch_type, patches)

def vector(self, dx, dy, x=0., y=0., **kwargs):
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@timhoffm timhoffm Feb 10, 2022

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Suggested change
def vector(self, dx, dy, x=0., y=0., **kwargs):
def vector(self, x, y, dx, dy, **kwargs):
  • We want to keep the API similar to arrow()
  • While from a mathemetical point of view, you can have a direction vector only specifying dx, dy; but we need to plot it somewhere and there is no reasonable default. I don't think there is a real use case where you are not interested how the arrow is positioned relative to other plot elements.
  • If you have all four parameters x, y, dx, dy is the natural order.

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@kmdalton kmdalton Feb 10, 2022

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This may be an peculiarity of my field, but crystallographers frequently plot arrows in the complex plane that are by default rooted at zero. As evidence that I am not alone, have a look at an image search for Argand diagram. From my perspective, x=y=0 is a sensible default. I can understand how this might not be universal.

I find vector(tail_x, tail_y, head_x, head_y, ...) is also a natural four-parameter representation. Is that one the table?

"""
Plot an arrow indicating a vector.

Parameters
----------
dx : float
The x-component of the vector
dy : float
The y-component of the vector
x : float (optional)
The x-coordinate of the vector's base if nonzero.
y : float (optional)
The y-coordinate of the vector's base if nonzero.

Other Parameters
----------------
**kwargs
`~matplotlib.patches.FancyArrowPatch` properties
"""
posA = (x, y)
posB = (x + dx, y + dy)

color = kwargs.pop("color", None)
if color is None:
color = self._get_lines.get_next_color()
vect = mpatches.FancyArrowPatch(posA, posB, color=color, **kwargs)
ms = vect._mutation_scale
stylekw = {
"head_length": kwargs.get("head_length", 12) / ms,
"head_width": kwargs.get("head_width", 12) / ms,
"tail_width": kwargs.get("tail_width", 4) / ms,
}
Comment on lines +6812 to +6817
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@ianhi ianhi Feb 9, 2022

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For context this numbers are based on how annotate styles it's arrows.

vect.set_arrowstyle(kwargs.get("arrowstyle", "simple"), **stylekw)
self.add_patch(vect)
self.update_datalim([posA, posB])
self._request_autoscale_view()
return vect

@_preprocess_data()
def stairs(self, values, edges=None, *,
orientation='vertical', baseline=0, fill=False, **kwargs):
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