Using Pylint in Ipython (Jupyter-Notebook)

Question

I want to run Pylint or any equivalent while using Jupyter-Notebook. Is there a way to install and run Pylint this way?

Answer 1

pycodestyle is an equivalent of pylint for Jupyter Notebook which is able to check your code against the PEP8 style guide.

First, you need to install the pycodestyle in jupyter notebook by typing this command,

!pip install pycodestyle pycodestyle_magic

Run this command in a cell of jupyter notebook. After successful installation, you have to load the magic in a Jupyter Notebook cell like this,

%load_ext pycodestyle_magic

Then, you have to use pycodestyle in a cell in which you want to investigate your code against PEP8 standards.

Below are some examples for more and clear understanding,

%%pycodestyle
a=1

Output: pycodestyle will give you this message,

2:2: E225 missing whitespace around operator

Another example,

%%pycodestyle
def square_of_number(
     num1, num2, num3, 
     num4):
    return num1**2, num2**2, num3**2, num4**2

Output:

2:1: E302 expected 2 blank lines, found 0
3:23: W291 trailing whitespace

Answer 2

I suggest you consider the nbQA tool:

pip install nbqa pylint
nbqa pylint my_notebook.ipynb

Besides pylint, nbqa makes it easy to run several other formatter and linter tools and is easy to integrate into your development workflow via their dedicated pre-commit hooks.

Answer 3

To answer the question more specifically in regards to pylint. One relatively simple way to achieve that in a development / ci environment (i.e. command line) is to convert the notebook to Python and then run the linting.

Let's assume you have notebooks in the ./notebooks folder and you have the jupyter and pylint command in the path, you could run the following:

jupyter nbconvert \
    --to=script \
    --output-dir=/tmp/converted-notebooks/ \
    ./notebooks/*.ipynb
pylint /tmp/converted-notebooks/*.py

You might want to configure pylint, as the notebook style is slightly different to a general Python module.

Some rules that you might want to disable:

• pointless-statement
• expression-not-assigned
• trailing-newlines
• wrong-import-position
• redefined-outer-name
• invalid-name

It also appears that the maximum number of characters in a cell (before horizontal scrolling) is 116 but that might depend on other factors.

(These options can for example be configured using the --max-line-length and --disable pylint arguments, or via the .pylintrc file)