Example for using cursor_data #12451
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| return ', '.join("Line('%s')" % line.get_label() for line in data) | ||
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| Line2D.mouseover = True |
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I'd rather you monkeypatch just the line instances that get returned by ax.plot; monkeypatching the classes themselves is a bit too global for me :)
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That would add the trouble of binding a method to an existing object. It makes it even more complicated to understand what's going on:
import matplotlib.pyplot as plt
import types
def patch_line(line):
"""Monkeypatch a line to show it's label on mouse-over."""
def lines_under_cursor(self, event):
"""
Return a list of lines under the cursor for the given MouseMove event.
"""
if not event.inaxes:
return []
return [line for line in event.inaxes.lines if line.contains(event)[0]]
def format_lines(self, data):
"""Convert a list of lines to a comma-separted string."""
return ', '.join("Line('%s')" % line.get_label() for line in data)
line.mouseover = True
line.get_cursor_data = types.MethodType(lines_under_cursor, line)
line.format_cursor_data = types.MethodType(format_lines, line)
fig, ax = plt.subplots()
l1, = ax.plot([1, 3, 2], label="Label 1", lw=3)
l2, = ax.plot([2, 1, 3], label="Label 2", lw=3)
patch_line(l1)
patch_line(l2)
plt.show()
Of course, you could bind a pure function in this case because self is not used, but that would lose generality.
Still not convinced that this monkey-patching is actually recommendable.
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Indeed, I would personally just bind free functions that don't take self as first argument. Doing it as suggested in your example is definitely overkill (as a side note, you can do line.get_cursor_data = get_cursor_data.__get__(type(line), line) which is a bit simpler IMO for the cases where you need it, or even just bind a partial() object... (there isn't much to gain by exactly binding a bound method)).
I'm not going to lose sleep over this specific example either way.
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Would it be more appropriate to subclass, such as:
class LabelShowingLine(Line2D):
def get_cursor_data(self, event):
...
def format_cursor_data(self, data):
...
ax.plot([1, 3, 2], label="Label 1", lw=3, cls=LabelShowingLine)
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l, = ax.plot(...)
l.__class__ = LabelShowingLine
hehe...
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FWIW this is how I would do it:
for line in ax.lines:
line.lines_under_cursor = lambda event: (
# Return a list of lines under the cursor for the given MouseEvent.
[line for line in event.inaxes.lines if line.contains(event)[0]]
if event.inaxes else [])
line.format_lines = lambda data: (
# Convert a list of lines into a comma-separated string.
", ".join("Line({!r})".format(line.get_label())) for line in data)
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I've come to the conclusion that monkeypatching is not a reasonable way to officially extend a library. I don't want to advertise it. After all, the gained feature is quite specialized and not something we need to provide as a core extensibility of matplotlib. #12463 is a stripped down version of this to just document the parameter type. Please feel free to reopen if there is a general consensus that we want people to monkeypatch matplotlib. |
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I actually think the example is fine, but am not going to lose sleep over whether to document it. |
PR Summary
Continues #12427, in particular #12427 (comment).