用于Matplotlib交互的IPython Notebook小部件 [英] IPython Notebook widgets for Matplotlib interactivity
问题描述
我想使用ipython notebook小部件为内联matplotlib图添加一定程度的交互性。
I would like to use the ipython notebook widgets to add some degree of interactivity to inline matplotlib plots.
一般情况下，情节可能很重，我只想更新情节的特定元素。我知道小部件内置的限制功能有助于不会泛滥内核，但是当情节需要30秒时，我不想等待这么长时间来更新一行。
In general the plot can be quite heavy and I want to only update a specific element of the plot. I understand that widgets have a throttling feature built-in that helps to don't flood the kernel, but when the plot takes let say 30s I don't want to wait so long just to update a line.
通过阅读示例笔记本，我能够创建一个基本示例，其中我将一个十字光标（由2个滑块驱动）添加到mpl轴。
By reading the example notebooks I was able to create a basic example in which I add a cross cursor (driven by 2 sliders) to a mpl axis.
问题是图形显示两次。这是代码（单元格1）：
The problem is that the figure is displayed twice. Here is the code (cell 1):
fig, ax = plt.subplots()
ax.plot([3,1,2,4,0,5,3,2,0,2,4])
...数字显示...，单元格2（编辑：感谢Thomas K的改进）：
... figure displayed ..., cell 2 (edit: thanks Thomas K for the improvement):
vline = ax.axvline(1)
hline = ax.axhline(0.5)
def set_cursor(x, y):
vline.set_xdata((x, x))
hline.set_ydata((y, y))
display(fig)
最后（单元格3）：
interact(set_cursor, x=(1, 9, 0.01), y=(0, 5, 0.01))
再次显示小部件的数字。
shows again the figure with the widgets.
所以问题是：
- 如何禁止显示第一个数字？
- 是正确的做法还是有更好的方法？
编辑
根据这个笔记本，允许禁止数字显示
I found an ipython config knob that, according to this notebook, allows inhibiting the figure display
%config InlineBackend.close_figures = False
虽然示例笔记本有效，但我无法弄清楚如何单独使用此选项（没有链接示例中提供的上下文管理器类）隐藏图形显示。
While the example notebook works, I can't figure out how to use this option by itself (without the context manager class provided in the linked example) to hide a figure display.
编辑2
我找到了<$ c的一些文档 $ c> InlineBackend.close_figures 可配置。
I found some documentation of the InlineBackend.close_figures configurable.
编辑3
由@shadanan回答触发，我想澄清一下我的目的是将光标添加到现有图形，而不是在每个光标移动时从头开始重绘图形。合并单个单元格中的3个单元格：
Triggered by @shadanan answer, I want to clarify that my purpose is to add a cursor to an existing figure without redrawing the plot from scratch at each cursor movement. Merging the 3 cells in a single cell:
fig, ax = plt.subplots()
ax.plot([3,1,2,4,0,5,3,2,0,2,4])
vline = ax.axvline(1)
hline = ax.axhline(0.5)
def set_cursor(x, y):
vline.set_xdata((x, x))
hline.set_ydata((y, y))
display(fig)
interact(set_cursor, x=(1, 9, 0.01), y=(0, 5, 0.01))
它应该有效，但事实并非如此。第一次执行单元格时，它显示了2个数字。小部件交互后，仅显示1个数字。这是一种奇怪的行为，需要像@shadanan回答中所示的解决方法。 ipython开发者可以对此发表评论吗？这是一个错误吗？
it "should" work but it doesn't. The first time the cell is executed it shows 2 figures. After widget interaction only 1 figure is displayed. This is the "strange behavior" that requires a workaround like the one shown in @shadanan answer. Can an ipython dev comment on this? Is it a bug?
推荐答案
解决方案结果非常简单。为了避免显示第一个数字，我们只需要在交互调用之前添加 close（）调用。
The solution turns out to be really simple. To avoid showing the first figure we just need to add a close() call before the interact call.
回顾问题的例子，像这样的单元格将正确显示一个交互式数字（而不是两个）：
Recalling the example of the question, a cell like this will correctly show a single interactive figure (instead of two):
fig, ax = plt.subplots()
ax.plot([3,1,2,4,0,5,3,2,0,2,4])
plt.close(fig)
vline = ax.axvline(1)
hline = ax.axhline(0.5)
def set_cursor(x, y):
vline.set_xdata((x, x))
hline.set_ydata((y, y))
display(fig)
interact(set_cursor, x=(1, 9, 0.01), y=(0, 5, 0.01))
更简洁的方法是定义函数 add_cursor （在单独的单元格或脚本中）：
A cleaner approach is defining the function add_cursor (in a separate cell or script):
def add_cursor(fig, ax):
plt.close(fig)
vline = ax.axvline(1, color='k')
hline = ax.axhline(0.5, color='k')
def set_cursor(x, y):
vline.set_xdata((x, x))
hline.set_ydata((y, y))
display(fig)
interact(set_cursor, x=ax.get_xlim(), y=ax.get_ylim())
然后在我们想要添加交互式光标时调用它：
and then call it whenever we want to add an interactive cursor:
fig, ax = plt.subplots()
ax.plot([3,1,2,4,0,5,3,2,0,2,4])
add_cursor(fig, ax)
这篇关于用于Matplotlib交互的IPython Notebook小部件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
