the optional keywords 'head_pos' has been added to quiver. 'head_pos' can put the arrowhead at the tip tail or middle of the arrow shaft dictated by keywords matching 'pivot', or be passed a float in range 0-1 to specify the exact location on the arrow shaft.

PR Checklist

Has Pytest style unit tests
Code isFlake 8 compliant
New features are documented, with examples if plot related
Documentation is sphinx and numpydoc compliant
Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way

anntzer reviewed

Oct 9, 2019

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lib/matplotlib/quiver.py Outdated

		@@ -173,6 +174,15 @@

		'mid' is a synonym for 'middle'.

		head_pos : {'tail', 'mid', 'middle', 'tip'}, optional, default: 'tip'

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anntzerOct 9, 2019

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I would suggest having a single head_pos argument that takes either a string or a float, with "tail" synonymous to 0, "middle" synonymous to 0.5, and tip synonymous to 1 (or reverse 0 and 1 -- it's actually not clear from the docstring which is which).
Also perhaps the pivot kwarg should also gain the same functionality?

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PipGryllsOct 9, 2019

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I was following the style of pivot for similarity within the module. But in principle, I agree with you both should probably be more flexible. I am not sure however if the angles become significantly more complex if the pivot parameter is let loose.

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PipGryllsOct 9, 2019

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I have made the edits to head_pos and committed changes I have not edited pivot but this could be opened as a feature request should people actually want it.

anntzer reviewed

Oct 9, 2019

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lib/matplotlib/quiver.py Outdated

		if 0.0 < mid_scale < 1.0:
		self.mid_scale = mid_scale
		else:
		self.mid_scale = 0.5

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anntzerOct 9, 2019•
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please error out in that case ("Errors should never pass silently.")
... or perhaps it actually makes sense to allow arrowheads outside of the shaft?

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PipGryllsOct 9, 2019

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I was thinking about this perhaps they should be left to be as the user specified and throw instead a warning that the arrows will be off the shaft?
If I have more time I would also think about allowing this to be a 1D array to allow the arrowhead position on the shaft to convey extra information. This would be a reason for mid_scale and head_pos to stay independent I think as your other comment.

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timhoffmOct 9, 2019

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For now, I would just error out. We can always expand the functionality later on if there is demand.

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PipGryllsOct 9, 2019

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I have made the edits and committed changes

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timhoffm commentedOct 14, 2019

Please add E402 forquiver_head_pos_demo.py in.flake8.

timhoffm reviewed

Oct 15, 2019

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examples/images_contours_and_fields/quiver_head_pos_demo.pyShow resolvedHide resolved

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QuLogic commentedSep 25, 2020

The idea of this looks sound, and it doesn't appear that there's any opposition, but it seems to have been forgotten for a while. It now needs a rebase to fix conflicts, and there may be a few small typos to fix.

QuLogic added status: needs rebase New feature labels

Sep 25, 2020

PipGrylls added8 commits

September 25, 2020 08:41

modified quiver to allow for positioning of the arrowheads on the shaft

e89fc0f

adjusting example

e2808e8

removed mid_scale to add the feature to head pos, also made putting a…

a6fa90c

…n error outside the range thow a value error instead of defaulting to 0.5

added typecheck to headpos before doing GT/LT operation

24c4da8

resolving flake 8 issues

e66498a

removing debugging lines

aa44e32

added error to .flake8

ba6e421

heading marker length

1524d55

PipGrylls force-pushed thequiverdev branch from2b2f39a to1524d55Compare

September 25, 2020 07:44

PipGrylls added2 commits

September 25, 2020 08:58

Fixing line in quiver

621da10

Fixing flake errors

3c0088e

QuLogic reviewed

Sep 25, 2020

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examples/images_contours_and_fields/quiver_head_pos_demo.py OutdatedShow resolvedHide resolved

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lib/matplotlib/quiver.py OutdatedShow resolvedHide resolved

lib/matplotlib/quiver.py

Comment on lines -473 to +484

		self._axes = ax # The attr actually set by the Artist.axes property.
		self.ax = ax
		# modified quiver to allow for positioning of the arrowheads on the
		# shaft

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QuLogicSep 25, 2020

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I don't think this change is intentional

lib/matplotlib/quiver.py

		@@ -487,6 +498,25 @@ def __init__(self, ax, *args,
		self.angles = angles
		self.width = width

		# Checks the boundaries of mid_scale if outside range default of 0.5
		if (head_pos == 0.0) or (head_pos == "tail"):

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QuLogicSep 25, 2020

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There's no need to check both 0.0 and 'tail'. Instead, check for 'tail' (and the other strings), and sethead_pos = 0.0 as appropriate. Then do a final check for0.0 <= head_pos <= 1.0.

lib/matplotlib/quiver.py

		@@ -50,7 +50,8 @@
		arrow more pointed, reduce headwidth or increase headlength and
		headaxislength. To make the head smaller relative to the shaft,
		scale down all the head parameters. You will probably do best to leave
		minshaft alone.
		minshaft alone. To set the position of the arrowhead used head_pos and
		to exactly position the head on the shaft use mid_scale.

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QuLogicSep 25, 2020

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What ismid_scale? It doesn't appear to be part of this PR.

lib/matplotlib/quiver.py

		Y[:, 6] = np.ones(np.shape(Y[:, 6])) * 0.5
		Y[:, 5:-1] *= -1
		else:
		raise ValueError("'head_pos' must be "

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QuLogicSep 25, 2020

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This has already been checked earlier, so no need to do so again.

PipGryllsand others added6 commits

September 28, 2020 07:43

Update examples/images_contours_and_fields/quiver_head_pos_demo.py

4e160ed

Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>

Update lib/matplotlib/quiver.py

a41ab8d

Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>

Update lib/matplotlib/quiver.py

93d8691

Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>

Update lib/matplotlib/quiver.py

670c203

Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>

removing 'mid scale

5490235

removing fixing commit

d975772

dopplershift requested changes

Sep 28, 2020

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lib/matplotlib/quiver.py

		self.head_pos = 1.0
		elif (head_pos == "mid") or (head_pos == "middle"):
		self.head_pos = 0.5
		elif type(head_pos) == float:

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dopplershiftSep 28, 2020

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If you combine this into:

elif type(head_pos)==floatand0.0<head_pos<1.0:

then you only need the single finalelse to raiseValueError.

lib/matplotlib/quiver.py

		"or a string in {'tail', 'middle', 'tip'}")
		else:
		raise ValueError("'head_pos' must be "
		"a value in the bounds 0head_pos<1,"

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Typo: "0head_pos<1,"

jklymak added status: needs revision and removed status: needs rebase labels

Dec 3, 2020

jklymak marked this pull request as draft

December 3, 2020 15:29

github-actionsbot added the status: needs rebase label

Oct 18, 2022

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github-actionsbot commentedJun 28, 2023

Since this Pull Request has not been updated in 60 days, it has been marked "inactive." This does not mean that it will be closed, though it may be moved to a "Draft" state. This helps maintainers prioritize their reviewing efforts. You can pick the PR back up anytime - please ping us if you need a review or guidance to move the PR forward! If you do not plan on continuing the work, please let us know so that we can either find someone to take the PR over, or close it.

github-actionsbot added the status: inactiveMarked by the “Stale” Github Action label

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melissawm commentedJun 28, 2023

Hi@PipGrylls - are you interested in picking this back up? If you need help with the rebase or moving forward, please let us know!

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PipGrylls commentedJun 28, 2023 via email

Hi,I won’t be picking this back up. I tried to fix the issues when I first pushed, happy for anyone to fix the minor bugs and finish the PR.Philip (Pip) Grylls, Dr***@***.*** ***@***.***>

…

On 28 Jun 2023, at 14:14, Melissa Weber Mendonça ***@***.***> wrote: Hi@PipGrylls <https://github.com/PipGrylls> - are you interested in picking this back up? If you need help with the rebase or moving forward, please let us know! — Reply to this email directly, view it on GitHub <#15396 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AFOHDM273V7SQ5PFVLDL3XLXNQU2PANCNFSM4I63XHEQ>. You are receiving this because you were mentioned.

rcomer added status: orphaned PR and removed status: inactiveMarked by the “Stale” Github Action labels

Jun 28, 2023

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New feature status: needs rebase status: needs revision status: orphaned PR

8 participants

		@@ -50,7 +50,8 @@
		arrow more pointed, reduce headwidth or increase headlength and
		headaxislength. To make the head smaller relative to the shaft,
		scale down all the head parameters. You will probably do best to leave
		minshaft alone.
		minshaft alone. To set the position of the arrowhead used head_pos and
		to exactly position the head on the shaft use mid_scale.

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PipGrylls commentedOct 9, 2019• editedLoading Uh oh!There was an error while loading.Please reload this page.

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QuLogic commentedSep 25, 2020

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PipGrylls commentedOct 9, 2019•
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anntzerOct 9, 2019•
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