IPython笔记本 - 提前退出单元格

I'd like to programmatically exit a cell early in IPython Notebook. exit(0), however, kills the kernel.

我想以编程方式在IPython Notebook早期退出单元格。但是,exit(0)会杀死内核。

Whats the proper way to do this? I'd prefer not to split the cell or manually halt execution.

什么是正确的方法呢?我不想拆分单元格或手动停止执行。

3 个解决方案

#1

Slightly more "proper" options:

略微更“适当”的选择:

This will get you out of all but the worst try/except blocks.

除了最差的try / except块之外,这将使你脱离所有。

raise KeyboardInterrupt

A little cleaner version of yours:

你的一个更干净的版本:

assert(False)

or simply:

raise

if you want to save a couple keystrokes.

如果你想节省一些按键。

#2

This is far from "proper" but one way to exit early is to create a runtime error. So instead of returning early from a script cleanly with exit(0) one can return uncleanly with something like

这远非“正确”,但提前退出的一种方法是创建运行时错误。因此,不是通过exit(0)干净地从脚本返回,而是可以使用类似的东西不清楚地返回

print(variable_to_query)
() + 1

which will run the code up until this point (completing the print statement) and then fail.

这将运行代码直到这一点(完成print语句)然后失败。

#3

I'm reposting my answer from here because the solution should apply to your question as well. It will...

我在这里重新发布我的答案,因为解决方案也适用于你的问题。它会...

not kill the kernel on exit

退出时不要杀死内核

not display a full traceback (no traceback for use in IPython shell)

不显示完整的回溯(没有在IPython shell中使用的回溯)

not force you to entrench code with try/excepts

不要强迫你用try / excepts来修改代码

work with or without IPython, without changes in code

使用或不使用IPython,无需更改代码

Just import 'exit' from the code beneath into your jupyter notebook (IPython notebook) and calling 'exit()' should work. It will exit and letting you know that...

只需从下面的代码中导入'退出'进入你的jupyter笔记本(IPython笔记本)并调用'exit()'就行了。它会退出并让你知道......

 An exception has occurred, use %tb to see the full traceback.

 IpyExit

"""
# ipython_exit.py
Allows exit() to work if script is invoked with IPython without
raising NameError Exception. Keeps kernel alive.

Use: import variable 'exit' in target script with
     'from ipython_exit import exit'    
"""

import sys
from io import StringIO
from IPython import get_ipython


class IpyExit(SystemExit):
    """Exit Exception for IPython.

    Exception temporarily redirects stderr to buffer.
    """
    def __init__(self):
        # print("exiting")  # optionally print some message to stdout, too
        # ... or do other stuff before exit
        sys.stderr = StringIO()

    def __del__(self):
        sys.stderr.close()
        sys.stderr = sys.__stderr__  # restore from backup


def ipy_exit():
    raise IpyExit


if get_ipython():    # ...run with IPython
    exit = ipy_exit  # rebind to custom exit
else:
    exit = exit      # just make exit importable

#1