Unable to send string version of DataFrame to pyperclip

Question

On Windows 10, under Anaconda, I've installed pyperclip so that I can copy content normally viewed in the Spyder console: conda install -c conda-forge pyperclip. Wihtout this, lengthy output scrolls off the top of the console terminal and is lost because of the limited capture depth.

As a test of correct functionality, the following allows me to paste the copied string "dog" into a Cygwin xterm:

import pyperclip as pc
pc.copy("dog")

To meet pyperclip's input requirements, I convert the sys.modules dict into a DataFrame DFstr, then export it to a string:

import pandas as pd
import sys
DFstr = pd.DataFrame( sys.modules.items(),
                      columns=["Local name", "Module"] ).to_string
DFstr # Show string content

   <bound method DataFrame.to_string of                     Local name                                             Module
   0                          sys                          <module 'sys' (built-in)>
   1                     builtins                     <module 'builtins' (built-in)>
   2            _frozen_importlib           <module 'importlib._bootstrap' (frozen)>
   3                         _imp                         <module '_imp' (built-in)>
   4                      _thread                      <module '_thread' (built-in)>
                          ...                                                ...
   1758               bs4.builder  <module 'bs4.builder' from 'C:\\Users\\User.Name...
   1759                       bs4  <module 'bs4' from 'C:\\Users\\User.Name\\anacon...
   1760         zmq.utils.garbage  <module 'zmq.utils.garbage' from 'C:\\Users\\U...
   1761  pandas.io.formats.string  <module 'pandas.io.formats.string' from 'C:\\U...
   1762    pandas.io.formats.html  <module 'pandas.io.formats.html' from 'C:\\Use...
   [1763 rows x 2 columns]>

However, DFstr fails to copy to the pyperclip "clipboard":

pc.copy(DFstr)

   Traceback (most recent call last):

   Cell In[49], line 1
     pc.copy(DFstr)

   File
   ~\anaconda3\envs\py39\lib\site-packages\pyperclip\__init__.py:463
   in copy_windows
     text = _stringifyText(text) # Converts non-str values to str.

   File
   ~\anaconda3\envs\py39\lib\site-packages\pyperclip\__init__.py:111
   in _stringifyText
     raise PyperclipException('only str, int, float, and bool values
        can be copied to the clipboard, not %s' % (text.__class__.__name__))

   PyperclipException:
   only str, int, float, and bool values
   can be copied to the clipboard, not method

What can I do to trace down the problem?

Answer 1

As per the error message, DFstr is a method, which pyperclip.copy() will not accept. The reason why it is a method instead of a string is because it was assigned DataFrame.to_string instead of DataFrame.to_string(). The former is a method, whereas the latter is an invocation of method to_string(), which returns a string [1].

When invoking a class/object method with zero arguments, some languages will allow you to dispense with the brackets () for enclosing arguments, but not Python. It doesn't interpret bracket-less function names as invocations, but rather, as referring to the functions/methods themselves.

Notes

[1] See help(pd.DataFrame.to_string).