--- title: "Smoother Python with automatic imports | pyflyby" description: "This is not a flaky works half the time kind of plugin, it's a seriously smooth editing experience. I've just started using pyflyby, and it is solid so far...." date: 2021-12-20 published: true tags: - ipython - python - terminal template: blog-post --- This is not a flaky works half the time kind of plugin, it's a seriously smooth editing experience. I've just started using pyflyby, and it is solid so far. I have automatic imports on every save of a python file in neovim, and automatic imports on every command in ipython. I can't tell you how pumped I am for this, and how good its felt to use over the past few weeks. It's glorious. ## YouTube video _Listen to me rant on how great pyflyby is_ [https://youtu.be/2QW5DJiEJH4](https://youtu.be/2QW5DJiEJH4){.youtube-embed} Give the video a watch, I did not have noise-cancelling on in obs. My apologies for the background hum and the mic stand bumps. I did my best to fix them up. ## Installation _How to install pyflyby for automatic python imports_ pyflyby is hosted on pypi, so you can get it with pip. I have had no issues installing it on 3.8+ so far. ``` bash pip install pyflyby ``` ## Configuration setup with stow _always stow your dotfiles_ If you're going to configure any of your tools the first thing you should do is set it up with stow, seriously don't sleep on the stow. If you don't have stow installed or choose not to use stow you can skip this part. ``` bash cd ~/dotfiles mkdir ipython touch ipython/.pyflyby stow ipython ``` > Seriously don't sleep on the stow. ## How to Configure pyflyby _it's just a file full of import statements_ `pyflyby` is configured simply by putting all of your import statements that you want to automatically import into your `~/.pyflyby` file. You can `import pandas`, `from pandas import DataFrame`, or even `import pandas as pd`, and all of these will work pretty much as expected. ``` python # comments start with a # # import your favorite libraries import visidata as vd import fsspec import difflib import s3fs import seaborn as sns import plotly # also supports from imports from rich.layout import Layout from rich.live import Live # duplicates are allowed import plotly import plotly # duplicate names from different libraries are not allowed import copy from numpy import copy ``` > Add all the things you would like to be imported automatically, just as you > would import them. I went kinda crazy and added over 200 to mine based on > packages that I use. ## Commas are even supported _yep all the import styles are supported_ This following example will set up auto import for both DataFrame and Series, they will both work separately. I removed these from my config as I felt it was cleaner without, but it works with them. ``` python from pandas import DataFrame, Series ``` > Even imports with a comma will be treated separately. ## Jupyter note _Both work the same, use what your comfortable with_ I only really mention ipython here, but the same all applies to Jupyter as well. I just really like ipython itself, c'mon its right there in the terminal integrating with the rest of your terminal experience so well. ## Ipython setup _Automatically import python libraries in ipython with pyflyby_ The recommended way to set uppyflybyfrom the docs is to run the following magic command. This works well, but I want even less typing, I want pyflyby automatically installed and importing things without me even thinking about it. ``` python %load_ext pyflyby ``` ![basic example of pyflyby](https://images.waylonwalker.com/load_ext_pyflyby.gif) ## Ipython setup next level _automatically import modules in python **without %load_ext**_ I really want pyflyby to just work in every environment without me thinking much about it. I want it to load automatically, and even to attempt to install itself if it's missing. ``` python from IPython import get_ipython import subprocess ipython = get_ipython() try: ipython.magic("load_ext pyflyby") except ModuleNotFoundError: print("installing pyflyby") subprocess.Popen( ["pip", "install", "pyflyby"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, ).wait() ipython.magic("load_ext pyflyby") ``` > Note: if installation fails you will still make it into ipython, there will > just be a traceback to the failed command as you enter. I've had zero issues with this, but if there ever comes a time when it does not work in certain environments for you. I'd strongly suggest you to add this to a separate profile. Ipython-Config > Check out this article for a bit more in depth ipython configuration ## ipython auto import examples pyflyby can import all the various import types just fine. * import something * from module import something * import something as alias ``` python df = pd.read_csv("https://waylonwalker.com/cars.csv") [PYFLYBY] import pandas as pd ``` ## Getting Help Want help on something that you have in your pyflyby config, just give it the `?`, `??`, or `help` and pyflyby will import it for you. ``` python Popen? ``` Just Ask Ipython for help ## Autocomplete _This is next level python auto-import_ pyflyby even goes as far as helping tab completion. If you try to tab complete `Pop` it will complete to `Popen` without even adding `Popen` to your local namespace. If you ask for something inside of a module i.e. `requests.`, then it will import requests. ``` python # does not populate the namespace Pop # !!does populate the local namespace requests. ``` ## What happens when a module is not installed _ModuleNotFoundError_ When you are in an environment where you do not have a module installed that is in your pyflyby config, it will throw a `ModuleNotFoundError` when it tries to import, and it will not import or try to install for you. You will have to change environments or install that module. ``` python ❯ pd? [PYFLYBY] import pandas as pd [PYFLYBY] Error attempting to 'import pandas as pd': ModuleNotFoundError: No module named 'pandas' [PYFLYBY] Traceback (most recent call last): [PYFLYBY] File "/home/u_walkews/.local/lib/python3.8/site-packages/pyflyby/_autoimp.py", line 1610, in _try_import [PYFLYBY] exec_(stmt, scratch_namespace) [PYFLYBY] File "", line 1, in [PYFLYBY] ModuleNotFoundError: No module named 'pandas' Object `pd` not found. ❯ df = pd.read_csv("https://waylonwalker.com/cars.csv") :1 in NameError: name 'pd' is not defined ``` ## nvim pyflyby setup _automatically importing python modules in vim, neovim, nvim_ This is by far the best part of this article. It makes development so fluid. It's not necessarily all about the speed. It really helps you move at the speed of your thoughts, without needing to worry about imports. Remembering where deeply nested modules are does not need to be a thing. ``` vim function! s:PyPreSave() Black endfunction function! s:PyPostSave() execute "silent !tidy-imports --black --quiet --replace-star-imports --action REPLACE " . bufname("%") execute "e" endfunction :command! PyPreSave :call s:PyPreSave() :command! PyPostSave :call s:PyPostSave() augroup waylonwalker autocmd! autocmd bufwritepre *.py execute 'PyPreSave' autocmd bufwritepost *.py execute 'PyPostSave' autocmd bufwritepost .tmux.conf execute ':!tmux source-file %' autocmd bufwritepost .tmux.local.conf execute ':!tmux source-file %' autocmd bufwritepost *.vim execute ':source %' augroup end ``` ![running pyflyby on save in nvim](https://images.waylonwalker.com/pyflyby-nvim.gif) ## refactoring _This is where it really shines_ This setup really shines when you are refactoring. You can freely move modules and classes around without worrying about bringing imports with them. Often when refactoring some modules from one file to another the most tedious part is editing the imports. Often you can't even grab whole lines because there are several imports and some are needed in both places but not all. pyflyby handles all this like a champ. ![simple refactoring example with pyflyby](https://images.waylonwalker.com/pyflyby-refactoring.gif) ## Where to install for vim _just make sure the tidy-imports command is available to vim_ pyflyby goes into the environment that you have active at the time that you start neovim. Typically, this is the virtual environment that I am using for the project I am editing. ## What gets imported/removed _only give me what I actually use_ Anything within the base config of pyflyby or your own config specified in `~/.pyflyby` will get automatically imported if it is used within the file/console. If you are working in a file, and stop using a module, it will automatically get removed. * Anything that is used, and found in the config is added * Anything that is unused gets removed ## Where does it put imports _after the last import_ `pyflyby` does not sort imports into paragraphs or by category. When it needs to add new imports. It will find the last paragraph of imports in your file, add the new one, and sort that paragraph alphabetically. ``` python from collections import Counter import requests from plugins.custom_seo import post_render # <-- pyflyby will put the import here ``` ## What about isort _put those imports where they go_ I did not like that I was getting pre-commit issues when using pyflyby, so I added isort to my chain of autocommands to automatically run isort and make my pre-commit happy. ``` vim function! s:PyPostSave() execute "silent !tidy-imports --black --quiet --replace-star-imports --action REPLACE " . bufname("%") execute "silent !isort " . bufname("%") execute "e" endfunction ``` Let's write some code ``` python def get(): """ Get all the posts from waylonwalker.com. Yes theres an rss feed, you should be subscribed if your not already. Oh, and we don't need no stinkin error handing because it's always live """ r = requests.get("https://waylonwalker.com/rss.xml") return r.content ``` Save it and pyflyby will inject requests into our file automatically, no need to type that out anymore. ``` python import requests def get(): """ Get all the posts from waylonwalker.com. Yes theres an rss feed, you should be subscribed if your not already. Oh, and we don't need no stinkin error handing because it's always live """ r = requests.get("https://waylonwalker.com/rss.xml") return r.content ``` ## What about **init** / api's _careful to fill in the `__all__` like you are supposed to_ Files such as **init**.py often import things they do not need, this is simply there for a convenience of the library user and to make the api cleaner. These type of modules should implement a `__all__` list of all the unused things that are imported according to pep8. Pyflyby will remove any unused modules unless they are in the `__all__` list. ``` python # snippet from kedro.extras.datasets.pandas __all__ = [ "CSVDataSet", "ExcelDataSet", "FeatherDataSet", "GBQTableDataSet", "ExcelDataSet", "AppendableExcelDataSet", "HDFDataSet", "JSONDataSet", "ParquetDataSet", "SQLQueryDataSet", "SQLTableDataSet", ] ``` ![pyflyby in **init** files](https://images.waylonwalker.com/pyflyby-__all__.gif) ## py command _one liners that need imports_ pyflyby also comes with a cli command to run one liners. It's pretty genius, I'm sure I will find a use or two for it, but so far it's been more of a novelty for me. ``` bash py help pd py help pd.DataFrame py pd.read_csv 'https://waylonwalker.com/cars.csv' ``` ![pyflyby's py command can run one liners from bash or zsh even with imports](https://images.waylonwalker.com/pyflyby-py.gif) ## Links * [pyflyby repo](https://github.com/deshaw/pyflyby) * [docs](https://deshaw.github.io/pyflyby/) * [My YouTube Video for pyflyby](https://youtu.be/2QW5DJiEJH4) * [configuring ipython](https://waylonwalker.com/ipython-config/) * [asking ipython for help??](https://waylonwalker.com/ipython-help/) * [sample data I used with pandas](https://waylonwalker.com/cars.csv) * [my rss feed](https://waylonwalker.com/rss.xml)