在IPython中分页标准输出 [英] Paging stdout output in IPython

问题描述

是否可以在（交互式）IPython会话中通过寻呼机传递 stdout 输出，例如 less ？如果是这样，怎么样？

例如，在

 在[1]中：来自some_module import function_that_prints_a_lot 
 
在[2]中：function_that_prints_a_lot（）
 
 ...所有内容都滚动... 
  

我想翻页 stdout 输出 function_that_prints_a_lot 。

另一个例子：

 在[1]中：％运行script_that_prints_a_lot.py 
  

我查看了IPython

分页输出

您可以使用magin ％page

 ％page -r< variablename> 
  

https://ipython.readthedocs.io/en/stable/interactive/magics.html#magic-page

或者你可以从IPython.core导入页面使用Ipython代码

  
 page.page （变量）
  

有关详细信息，请参阅以下内容

PS：一些有用的主题

如何从Python函数调用中捕获stdout输出？

如何在python中重定向函数的打印输出

https://github.co m / ipython / ipython / wiki / Cookbook：-sending-built-in-help-to-the pager

重载打印python

Is it possible in an (interactive) IPython session to pass the stdout output through a pager, like less? If so, how?

For example, in

In [1]: from some_module import function_that_prints_a_lot

In [2]: function_that_prints_a_lot()

... everything scrolls away ...

I would like to page through the stdout output of function_that_prints_a_lot.

Another example:

In [1]: %run script_that_prints_a_lot.py

I've looked through IPython magic commands but didn't find any solution.

解决方案

As discussed in chat there is no simple way of doing this. Since the function prints the values, the only thing you can do is Capture output + Then page output. There are few issues on jupyter that you might be interested in

https://github.com/jupyter/notebook/issues/2049

https://github.com/ipython/ipython/issues/6516

Capturing output

Output capturing can be done multiple ways

1. Overload Print Method

import sys
data = ""
def myprint(value, *args, sep=' ', end='\n', file=sys.stdout, flush=False):
    global data
    current_text = value + " ".join(map(str, args)) + "\n"
    data += current_text

original_print = print
print = myprint

def testing():
    for i in range(1,1000):
        print ("i =", i)

testing()

original_print("The output from testing function is", data)

2. Capture output using StringIO

from cStringIO import StringIO
import sys

class Capturing(list):
    def __enter__(self):
        self._stdout = sys.stdout
        sys.stdout = self._stringio = StringIO()
        return self
    def __exit__(self, *args):
        self.extend(self._stringio.getvalue().splitlines())
        del self._stringio    # free up some memory
        sys.stdout = self._stdout

Usage:

with Capturing() as output:
    do_something(my_object)

3. Capture output using redirect_stdout

import io
from contextlib import redirect_stdout

f = io.StringIO()
with redirect_stdout(f):
    do_something(my_object)
out = f.getvalue()

4. Capture using %%capture magic command

Paging Output

You can use magin %page

%page -r <variablename>

https://ipython.readthedocs.io/en/stable/interactive/magics.html#magic-page

Or you can use Ipython code

from IPython.core import page
page.page(variable)

For more details refer to below

PS: Some helpful threads

How to capture stdout output from a Python function call?

How can I redirect print output of a function in python

https://github.com/ipython/ipython/wiki/Cookbook:-Sending-built-in-help-to-the-pager

overload print python

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