pandas-method-chaining

pandas-method-chaining is a plugin for flake8 that provides method chaining linting for pandas code.

It is a fork from pandas-vet. The global framework of pandas-vet has been reused. All rules have been fully rewritten and adapted to pandas method chaining, except the one dealing with the use of inplace=True.

Motivation

The source of motivation is to help pandas users to write method chaining code style.

Why a fork? The original pandas-vet includes rules which don't deal with method chaining, and some of them are not compatible with this style (e.g. PD005 and PD006 using operators instead of methods).

A source of inspiration was Matt Harrisson's book Effective Pandas.

Limits

• False positives may occur: e.g., either non pandas statements matching the rules, or intentional style of the programmer.
• Output messages could be improved: e.g., either too general, or not adapted to specific cases.

Installation

pandas-method-chaining is a plugin for flake8. If you don't have flake8 already, it will install automatically when you install pandas-method-chaining.

For the moment, the plugin is on github only and can be installed, in a dedicated environment, after cloning the repo by:

$ pip install -e .

When this plugin meets its users, it will be added to PyPI to ease the installation.

Usage

Once installed successfully in an environment that also has flake8 installed, pandas-method-chaining should run using:

$ flake8 python_script.py --select=PMC

Contributors

Contributors from pandas-vet

• https://github.com/deppen8/pandas-vet#contributors

Other contributor

• fran6w

List of warnings

Except PMC001 which uses a should, other warnings use a could.

PMC001 usage of inplace=True should be avoided

PMC002 reassignment using call could be replaced by method chaining

PMC003 reassignment using subscript could be replaced by method chaining

PMC004 assignment using subscript could be replaced by assign()

PMC005 assignment using attribute could be replaced by assign()

PMC006 assignment of index or columns could be replaced by rename()

PMC007 selection reusing a variable could be performed with a lambda