ipython: how to set terminal width

After some digging through the code, it appears that the variable you're looking for is numpy.core.arrayprint._line_width, which is 75 by default. Setting it to 160 worked for me:

>>> numpy.zeros((2, 20))
array([[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0., 0.,  0.,  0.,  0.],
       [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.]])

The function used by default for array formatting is numpy.core.numeric.array_repr, although you can change this with numpy.core.numeric.set_string_function.

You can see your current line width with

numpy.get_printoptions()['linewidth']

and set it with

numpy.set_printoptions(linewidth=160)

Automatically set printing width

If you'd like the terminal width to be set automatically, you can have Python execute a startup script. So create a file ~/.python_startup.py or whatever you want to call it, with this inside it:

# Set the printing width to the current terminal width for NumPy.
#
# Note: if you change the terminal's width after starting Python,
#       it will not update the printing width.
from os import getenv
terminal_width = getenv('COLUMNS')
try:
    terminal_width = int(terminal_width)
except (ValueError, TypeError):
    print('Sorry, I was unable to read your COLUMNS environment variable')
    terminal_width = None

if terminal_width is not None and terminal_width > 0:
    from numpy import set_printoptions
    set_printoptions(linewidth = terminal_width)

del terminal_width

and to have Python execute this every time, open your ~/.bashrc file, and add

# Instruct Python to execute a start up script
export PYTHONSTARTUP=$HOME/.python_startup.py
# Ensure that the startup script will be able to access COLUMNS
export COLUMNS

To automatically resize both numpy and IPython whenever your window size changes, add the following to your ipython_config.py:

import IPython
import signal
import shutil
import sys
try:
    import numpy as np
except ImportError:
    pass

c = get_config()

def update_terminal_width(*ignored):
    """Resize the IPython and numpy printing width to match the terminal."""
    w, h = shutil.get_terminal_size()

    config = IPython.get_ipython().config
    config.PlainTextFormatter.max_width = w - 1
    shell = IPython.core.interactiveshell.InteractiveShell.instance()
    shell.init_display_formatter()

    if 'numpy' in sys.modules:
        import numpy as np
        np.set_printoptions(linewidth=w - 5)

# We need to configure IPython here differently because get_ipython() does not
# yet exist.
w, h = shutil.get_terminal_size()
c.PlainTextFormatter.max_width = w - 1
if 'numpy' in sys.modules:
    import numpy as np
    np.set_printoptions(linewidth=w - 5)

signal.signal(signal.SIGWINCH, update_terminal_width)

If you want to delay loading numpy until necessary, look at Post import hooks in Python 3 for a solution.

If you're not using IPython, put the above in your PYTHONSTARTUP file and remove the IPython-specific lines.