Draggable annotations: documentation and bugreport

Hi, I just found out somewhere on the web that annotations can be set to be draggable by just doing:

plt.annotate(...).draggable()

This is absolutely amazing! But I don't think this is documented anywhere, while it should be (or did I miss it?).

At the same time the behaviour is not perfect: often after dragging one annotation when trying to drag another, the first one would be dragged in the same direction (e.g. I drag the second along x axis, the first one does the same). Sometimes I would get even three annotations moving when I drag one of them.

It is very loosely documented: http://matplotlib.org/examples/pylab_examples/annotation_demo3.html

Odd that it is not in the API docs...

True, if you carefully look into that example you can realize it...

I agree that it should be much better documented and no one can be blamed for missing it as is.

I only found it by git grep on the source

What do you think of the bug? Or is it not a bug?

@blink1073

That is probably a bug, it would be worth having a look at the draggable selection logic. @blink1073 has been doing some very interesting / cool work with selection areas, it would be interesting to see if you could re-use any of that to make draggable annotations work better?

@blink1073

I am not entirely certain, but I think annotations became draggable by
accident via the draggable legend feature. So I guess that that code never
really got fully tested in situations with multiple annotations. Some
example code would be useful. We can then see if it really is a bug or a
feature.

On Wed, Jan 13, 2016 at 8:55 AM, Thomas A Caswell notifications@github.com
wrote:

That is probably a bug, it would be worth having a look at the draggable
selection logic. @blink1073 https://github.com/blink1073 has been doing
some very interesting / cool work with selection areas, it would be
interesting to see if you could re-use any of that to make draggable
annotations work better?

—
Reply to this email directly or view it on GitHub
#5839 (comment)
.

Example code:

import numpy as np
import matplotlib.pyplot as plt
x = np.arange(10)
y = x**2
text = [str(i) for i in zip(x, y)]
plt.scatter(x, y)
for a, b, c in zip(x, y, text):
    plt.annotate(c, xy=(a, b), xytext=(a, b+2), arrowprops=dict(arrowstyle="->", color='r', lw=0.5)).draggable()
plt.show()

Try dragging the annotations. Happens randomly, I think, or at least I haven't noticed a pattern.

I've noticed this behavior too. It does seem mostly random, but I've been able to get repeatable behavior doing this:

add two draggable annotations
move the second
move the first --> the second will move with it

Oddly, if you type a command (I run in IPython with interactive on), it seems to break that link. With more annotations, I noticed that many can be linked and typing a command doesn't break all of them.

One other thing I noticed is that the second step above causes a new ._transform member of the first annotation to be created (I only compared id's of all .__dict__ members ... before and after).

I think the bug was fixed in #10776 (somewhat indirectly); the documentation request remains.

Turns out this is the curse of private base classes again

This issue has been marked "inactive" because it has been 365 days since the last comment. If this issue is still present in recent Matplotlib releases, or the feature request is still wanted, please leave a comment and this label will be removed. If there are no updates in another 30 days, this issue will be automatically closed, but you are free to re-open or create a new issue if needed. We value issue reports, and this procedure is meant to help us resurface and prioritize issues that have not been addressed yet, not make them disappear. Thanks for your help!

This is unfortunately still undocumented.

This issue has been marked "inactive" because it has been 365 days since the last comment. If this issue is still present in recent Matplotlib releases, or the feature request is still wanted, please leave a comment and this label will be removed. If there are no updates in another 30 days, this issue will be automatically closed, but you are free to re-open or create a new issue if needed. We value issue reports, and this procedure is meant to help us resurface and prioritize issues that have not been addressed yet, not make them disappear. Thanks for your help!

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Draggable annotations: documentation and bugreport #5839

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Draggable annotations: documentation and bugreport #5839

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tacaswell commented on Jan 12, 2016

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