Seamlessly run Python code from Vim in IPython, including executing individual code cells similar to Jupyter notebooks and MATLAB.

ipython-cell is especially suited for data exploration and visualization using Python. You can for example define a code cell that loads your input data, and another code cell to visualize the data. This plugin allows you to change and re-run the visualization part of your code without having to reload the data each time.

ipython-cell requires Vim or Neovim to be compiled with Python 2 or Python 3 support (+python or +python3 when running vim --version). If both Python versions are found, the plugin will prefer Python 3.

ipython-cell depends on vim-slime to send the code to IPython, see Installation instructions below.

Additionally, the cell execution feature requires Tkinter and a clipboard program to be installed. On Linux, the plugin supports xclip and xsel (preferring the former). On macOS, the plugin will use pbcopy. Windows systems are currently not supported. There is also a verbose version of the cell execution feature that does not require Tkinter or a clipboard program, see Usage.

It is easiest to install ipython-cell using a plugin manager (I personally recommend vim-plug). See respective plugin manager's documentation for more information about how to install plugins.

Plug 'jpalardy/vim-slime', { 'for': 'python' }
Plug 'hanschen/vim-ipython-cell', { 'for': 'python' }

Plugin 'jpalardy/vim-slime'
Plugin 'hanschen/vim-ipython-cell'

NeoBundle 'jpalardy/vim-slime', { 'on_ft': 'python' }
NeoBundle 'hanschen/vim-ipython-cell', { 'on_ft': 'python' }

call dein#add('jpalardy/vim-slime', { 'on_ft': 'python' })
call dein#add('hanschen/vim-ipython-cell', { 'on_ft': 'python' })

cd ~/.vim/bundle
git clone https://github.com/hanschen/vim-ipython-cell.git

ipython-cell sends code from Vim to IPython using vim-slime. For this to work, IPython has to be running in a terminal multiplexer like GNU Screen or tmux, or in a Vim or Neovim terminal. I personally use tmux, but you will find screen installed on most *nix systems.

It is recommended that you familiarize yourself with vim-slime first before using ipython-cell. Once you understand vim-slime, using ipython-cell will be a breeze.

ipython-cell does not define any key mappings by default, but comes with the commands listed below, which I recommend that you bind to key combinations of your likings. The Example Vim Configuration shows some examples of how this can be done.

Note that the cell execution feature copies your code to the system clipboard. You may want to avoid using this feature if your code contains sensitive data.

:IPythonCellExecuteCell

Execute the current code cell in IPython. Requires a clipboard program

:IPythonCellExecuteCellJump

Execute the current code cell in IPython, and jump to the next cell. Requires a clipboard program

:IPythonCellExecuteCellVerbose

Print and execute the current code cell in IPython. Verbose version of IPythonCellExecuteCell that works without a clipboard program.

:IPythonCellExecuteCellVerboseJump

Print and execute the current code cell in IPython, and jump to the next cell. Verbose version of IPythonCellExecuteCellJump that works without a clipboard program.

:IPythonCellRun

Run the whole script in IPython.

:IPythonCellRunTime

Run the whole script in IPython and time the execution.

:IPythonCellClear

Clear IPython screen.

:IPythonCellClose

Close all figure windows.

:IPythonCellPrevCell

Jump to the previous cell header.

:IPythonCellNextCell

Jump to the next cell header.

:IPythonCellPrevCommand

Run previous command.

:IPythonCellRestart

Restart IPython.

You may want to send other commands to IPython, such as %debug and exit. vim-slime makes it easy to send arbitrary text to IPython from Vim using the SlimeSend1 command, for example

:SlimeSend1 %debug

You can then bind these commands to key mappings, see Example Vim Configuration below.

Code cells are defined by either Vim marks or special text in the code, depending on if g:ipython_cell_delimit_cells_by is set to 'marks' or 'tags', respectively. The default is to use Vim marks (see :help mark in Vim).

The examples below show how code cell boundaries work.

Marks are depicted as letters in the left-most column.

                                   _
  | import numpy as np              | cell 1
  |                                _| 
a | numbers = np.arange(10)         | cell 2
  |                                 |
  |                                _|
b | for n in numbers:               | cell 3
  |     print(n)                   _|
c |     if n % 2 == 0:              | cell 4
  |         print("Even")           |
  |     else:                       |
  |         print("Odd")            |
  |                                _|
d | total = numbers.sum()           | cell 5
  | print("Sum: {}".format(total)) _|

Note that code cells can be defined inside statements such as for loops. IPython's %paste will automatically dedent the code before execution. However, if the code cell is defined inside e.g. a for loop, the code cell will not iterate over the loop.

In the example above, executing cell 4 after cell 3 will only print Odd once because IPython will execute the following code:

for n in numbers:
    print(n)

for cell 3, followed by

if n % 2 == 0:
    print("Even")
else:
    print("Odd")

for cell 4. The for statement is no longer included for cell 4.

You must therefore be careful when defining code cells inside statements.

Using ## to define cell boundaries.

                                   _
import numpy as np                  | cell 1
                                   _|
## Setup                            | cell 2
                                    |
numbers = np.arange(10)             |
                                   _|
## Print numbers                    | cell 3
                                    |
for n in numbers:                   |
    print(n)                        |
                                   _|
    ## Odd or even                  | cell 4
                                    |
    if n % 2 == 0:                  |
        print("Even")               |
    else:                           |
        print("Odd")                |
                                   _|
## Print sum                        | cell 5
                                    |
total = numbers.sum()               |
print("Sum: {}".format(total))      |
print("Done.")                     _|

See note in the previous section about defining code cells inside statements (such as cell 4 inside the for loop in the example above).

g:ipython_cell_delimit_cells_by

Specify if cells should be delimited by 'marks' or 'tags'. Default: 'marks'

g:ipython_cell_tag

If cells are delimited by tags, specify the format of the tags. Default: '##'

g:ipython_cell_valid_marks

If cells are delimited by marks, specify which marks to use. Default: 'abcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'

Here's an example of how to configure your .vimrc to use this plugin. Adapt it to suit your needs.

" Load plugins using vim-plug
call plug#begin('~/.vim/plugged')
Plug 'jpalardy/vim-slime', { 'for': 'python' }
Plug 'hanschen/vim-ipython-cell', { 'for': 'python' }
call plug#end()

"------------------------------------------------------------------------------
" slime configuration 
"------------------------------------------------------------------------------
" always use tmux
let g:slime_target = 'tmux'

" fix paste issues in ipython
let g:slime_python_ipython = 1

" always send text to the top-right pane in the current tmux tab without asking
let g:slime_default_config = {
            \ 'socket_name': get(split($TMUX, ','), 0),
            \ 'target_pane': '{top-right}' }
let g:slime_dont_ask_default = 1

"------------------------------------------------------------------------------
" ipython-cell configuration
"------------------------------------------------------------------------------
" Use '##' to define cells instead of using marks
let g:ipython_cell_delimit_cells_by = 'tags'

" Keyboard mappings. <Leader> is \ (backslash) by default

" map <Leader>r to run script
nnoremap <Leader>r :IPythonCellRun<CR>

" map <Leader>R to run script and time the execution
nnoremap <Leader>R :IPythonCellRunTime<CR>

" map <Leader>c to execute the current cell
nnoremap <Leader>c :IPythonCellExecuteCell<CR>

" map <Leader>C to execute the current cell and jump to the next cell
nnoremap <Leader>C :IPythonCellExecuteCellJump<CR>

" map <Leader>l to clear IPython screen
nnoremap <Leader>l :IPythonCellClear<CR>

" map <Leader>x to close all Matplotlib figure windows
nnoremap <Leader>x :IPythonCellClose<CR>

" map [c and ]c to jump to the previous and next cell header
nnoremap [c :IPythonCellPrevCell<CR>
nnoremap ]c :IPythonCellNextCell<CR>

" map <Leader>h to send the current line or current selection to IPython
nmap <Leader>h <Plug>SlimeLineSend
xmap <Leader>h <Plug>SlimeRegionSend

" map <Leader>p to run the previous command
nnoremap <Leader>p :IPythonCellPrevCommand<CR>

" map <Leader>Q to restart ipython
nnoremap <Leader>Q :IPythonCellRestart<CR>

" map <Leader>d to start debug mode
nnoremap <Leader>d :SlimeSend1 %debug<CR>

" map <Leader>q to exit debug mode or IPython
nnoremap <Leader>q :SlimeSend1 exit<CR>

Note that the mappings as defined here work only in normal mode (see :help mapping in Vim for more information).

Moreover, these mappings will be defined for all file types, not just Python files. If you want to define these mappings for only Python files, you can put the mappings in ~/.vim/after/ftplugin/python.vim for Vim (or ~/.config/nvim/after/ftplugin/python.vim for Neovim).

If you come from the MATLAB world, you may want e.g. F5 to save and run the script regardless if you are in insert or normal mode, F6 to execute the current cell, and F7 to execute the current cell and jump to the next cell:

" map <F5> to save and run script
nnoremap <F5> :w<CR>:IPythonCellRun<CR>
inoremap <F5> <C-o>:w<CR><C-o>:IPythonCellRun<CR>

" map <F6> to evaluate current cell without saving
nnoremap <F6> :IPythonCellExecuteCell<CR>
inoremap <F6> <C-o>:IPythonCellExecuteCell<CR>

" map <F7> to evaluate current cell and jump to next cell without saving
nnoremap <F7> :IPythonCellExecuteCellJump<CR>
inoremap <F7> <C-o>:IPythonCellExecuteCellJump<CR>

Some features of ipython-cell use one of the following clipboard programs:

• Linux: xclip (preferred) or xsel.
• macOS: pbcopy (installed by default).
• Windows: not supported.

The IPythonCellExecuteCell and IPythonCellExecuteCellJump commands do not work, but other commands such as IPythonCellRun work. Why?

First, make sure you have Tkinter installed (otherwise you will get an error message) and a supported clipboard program. Also make sure your DISPLAY variable is correct, see next question. If you cannot install the requirements but still want to use the cell execution feature, you can try the verbose versions IPythonCellExecuteCellVerbose and IPythonCellExecuteCellVerboseJump.

IPythonCellExecuteCell and IPythonCellExecuteCellJump do not execute the correct code cell, or I get an error about 'can't open display', 'could not open display', 'could not connect to display', or something similar, what do I do?

Make sure your DISPLAY environment variable is correct, especially after re-attaching a screen or tmux session. In tmux you can update the DISPLAY variable with the following command:

eval $(tmux showenv -s DISPLAY)

Should I use 'marks' or 'tags' to define cells?

This depends on personal preference. I used to use 'tags' because they are similar to MATLAB's %% code sections. 'tags' are nice if you want the cells to be saved together with your files, and may be easier to start with. I switched to 'marks' after discovering that I can show the marks in the left-most column. I find 'marks' to be more flexible because you can add and change cells without changing the code, which is nice when your code is under version control.

How do I show the marks in the left-most column?

Use the vim-signature plugin: https://github.com/kshenoy/vim-signature

How to send only the current line or selected lines to IPython?

Use the features provided by vim-slime, see the Example Vim Configuration for an example. The default mapping C-c C-c (hold down Ctrl and tap the C key twice) will send the current paragraph or the selected lines to IPython. See :help slime for more information, in particular the documentation about <Plug>SlimeRegionSend and <Plug>SlimeLineSend.

Why do I get "name 'plt' is not defined" when I try to close figures?

ipython-cell assumes that you have imported matplotlib.pyplot as plt in IPython. If you prefer to import matplotlib.pyplot differently, you can achieve the same thing using vim-slime, for example by adding the following to your .vimrc:

nnoremap <Leader>x :SlimeSend1 matplotlib.pyplot.close('all')<CR>

How can I send other commands to IPython, e.g. '%who'?

You can easily send arbitrary commands to IPython using the :SlimeSend1 command provided by vim-slime, e.g. :SlimeSend1 %who, and map these commands to key combinations.

Why does this plugin not work inside a virtual environment?

If you use Neovim, make sure you have the neovim Python package installed.

Why isn't this plugin specific to Python by default? In other words, why do I have to add all this extra stuff to make this plugin Python-specific?

This plugin was created with Python and IPython in mind, but I don't want to restrict the plugin to Python by design. Instead, I have included examples of how to use plugin managers to specify that the plugin should be loaded only for Python files and how to create Python-specific mappings. If someone wants to use this plugin for other filetypes, they can easily do so.

Why is this plugin written in Python instead of pure Vimscript?

Because I feel more comfortable with Python and don't have the motivation to learn Vimscript for this plugin. If someone implements a pure Vimscript version, I would be happy to consider to merge it.

• tslime_ipython - Similar to ipython-cell but with some small differences. For example, tslime_ipython pastes the whole code that's sent to IPython to the input line, while ipython-cell uses IPython's %paste -q command to make the execution less verbose.
• vim-ipython - Advanced two-way integration between Vim and IPython. I never got it to work as I want, i.e., don't show the code that's executed but show the output from the code, which is why I created this simpler plugin.
• vim-tmux-navigator - Seamless navigation between Vim splits and tmux panes.
• vim-signature - Display marks in the left-hand column.

ipython-cell was heavily inspired by tslime_ipython. The code logic to determine which Python version to use was taken from YouCompleteMe.