如何在Jupyter Lab上使用“异步小部件"?

问题描述

我正在尝试复制官方的异步小部件-示例在jupyter 实验室上，但await永远不会继续.

I'm trying to reproduce the official Asynchronous Widgets-Example on jupyter lab, but the await never continues.

1. docker run --rm -p 8888:8888 -e JUPYTER_ENABLE_LAB=yes jupyter/datascience-notebook start-notebook.sh --NotebookApp.token=''
2. firefox 0.0.0.0:8888
3. 创建一个新的python3笔记本
4. 创建一个单元格并在下面输入代码
5. 运行单元格
6. 移动滑块

1. docker run --rm -p 8888:8888 -e JUPYTER_ENABLE_LAB=yes jupyter/datascience-notebook start-notebook.sh --NotebookApp.token=''
2. firefox 0.0.0.0:8888
3. create a new python3 notebook
4. create a cell and enter the code below
5. run cell
6. move slider

单元格的代码

%gui asyncio

import asyncio
def wait_for_change(widget, value):
    future = asyncio.Future()
    def getvalue(change):
        # make the new value available
        future.set_result(change.new)
        widget.unobserve(getvalue, value)
    widget.observe(getvalue, value)
    return future

from ipywidgets import IntSlider
slider = IntSlider()

async def f():
    for i in range(10):
        print('did work %s'%i)
        #x = await asyncio.sleep(1)
        x = await wait_for_change(slider, 'value')
        print('async function continued with value %s'%x)
asyncio.ensure_future(f())
#task = asyncio.create_task(f())
slider

预期结果

单元格输出

Expected result

The cell outputs

did work 0
async function continued with value 1
did work 1
async function continued with value 2
[...]

实际输出

第一个did work 0

• 我专门讲的是jupyter 实验室，而不是普通的jupyter笔记本

• I'm specifically talking about jupyter lab and not about regular jupyter notebooks

没有错误消息或任何东西.预期的输出不会发生

There is no error-message or anything. The expected output just doesn't happen

最小的asyncio示例在jupyter实验室中有效:

The minimal asyncio-example does work in jupyter lab:

import asyncio
async def main():
    print('hello')
    await asyncio.sleep(1)
    print('world')
await main()

• ，当您省去-e JUPYTER_ENABLE_LAB=yes时，会得到没有jupyter实验室的常规jupyter笔记本，并且会发生预期的结果.

  • when you leave out the -e JUPYTER_ENABLE_LAB=yes, then you get a regular jupyter notebook without jupyter lab and the expected result happens.

    这不是不是重复的 ipywidgets小部件值保持不变或 Jupyter Interactive Widget无法正确执行，因为这些问题包括jupyter lab或asyncio

    this is not a duplicate of ipywidgets widgets values not changing or Jupyter Interactive Widget not executing properly, because these questions nether include jupyter lab nor asyncio

    推荐答案

    实际上可以，但是jupyter会丢失打印输出.尝试以下代码:

    Actually it works, but jupyter lose print output.Try this code:

    from IPython.display import display
    import ipywidgets as widgets
    
    out = widgets.Output()
    
    import asyncio
    def wait_for_change(widget, value):
        future = asyncio.Future()
        def getvalue(change):
            # make the new value available
            future.set_result(change.new)
            widget.unobserve(getvalue, value)
        widget.observe(getvalue, value)
        return future
    
    
    
    from ipywidgets import IntSlider
    slider = IntSlider()
    
    # Now the key: the container is displayed (while empty) in the main thread
    async def f():
        for i in range(10):
            out.append_stdout('did work %s'%i)
            x = await wait_for_change(slider, 'value')
            out.append_stdout('async function continued with value %s'%x)
    asyncio.ensure_future(f())
    
    display(slider)
    display(out)
    

    您可以在此处找到更多详细信息: https://github. com/jupyter-widgets/ipywidgets/issues/2567#issuecomment-535971252

    You can find more details here: https://github.com/jupyter-widgets/ipywidgets/issues/2567#issuecomment-535971252

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