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macOSでpythonを使えるようにした

Last updated at Posted at 2021-01-01

背景

macOS BigSurでpythonをつかおうとおもった。
(CuteRというコマンドを使いたかった:CuteRでQRコード画像をつくった

ところが、pipをつかうと

$ pip install
dyld: Library not loaded: /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
  Referenced from: /Library/Frameworks/Python.framework/Versions/3.6/Resources/Python.app/Contents/MacOS/Python
  Reason: image not found
Abort trap: 6

となってしまう。

$ python3でもおなじ。

基本的な方向性

macOS環境のPython:https://www.python.jp/install/macos/index.html

によると

  • macOSに入っているpythonを使おうとするな
  • Homebrewでインストールせよ
  • pip3でなくてpython3.9 -m pip xxxとせよ
  • venvなど仮想環境で動かせ

ということだそう。ここでは、上の3つまでやってみた。

作業ログ

$ brew updateすると、まずはgit - C ...をせよとのお達し。

$ brew update
Error: homebrew-core is a shallow clone. To `brew update` first run:
  git -C "/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core" fetch --unshallow

まずはfetchして、$ brew update

$ git -C "/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core" fetch --unshallow
remote: Enumerating objects: 690418, done.
remote: Counting objects: 100% (690359/690359), done.
remote: Compressing objects: 100% (233146/233146), done.
remote: Total 680792 (delta 450632), reused 674814 (delta 444788), pack-reused 
Receiving objects: 100% (680792/680792), 271.20 MiB | 14.34 MiB/s, done.
Resolving deltas: 100% (450632/450632), completed with 7510 local objects.
From https://github.com/Homebrew/homebrew-core
   baf6aab591..b293a33dd8 master     -> origin/master

$ brew update

pythonのインストール。

$ brew install python
Warning: python@3.9 3.9.1_3 is already installed, it's just not linked
You can use `brew link python@3.9` to link this version.

入っているらしい。リンクすればいいのね。

$ brew link python@3.9
Linking /usr/local/Cellar/python@3.9/3.9.1_3... 
Error: Could not symlink bin/2to3
Target /usr/local/bin/2to3
already exists. You may want to remove it:
  rm '/usr/local/bin/2to3'

To force the link and overwrite all conflicting files:
  brew link --overwrite python@3.9

To list all files that would be deleted:
  brew link --overwrite --dry-run python@3.9

ふむ、rmしてbrew linkね。

$ rm '/usr/local/bin/2to3'
$ brew link --overwrite python@3.9
Linking /usr/local/Cellar/python@3.9/3.9.1_3... 25 symlinks created

これをしたけど、

$ pip install 
$ python3

とすると、また冒頭と同じエラー。そうではなくて

$ python3.9
Python 3.9.1 (default, Dec 28 2020, 11:25:16) 
[Clang 12.0.0 (clang-1200.0.32.28)] on darwin
Type "help", "copyright", "credits" or "license" for more information.

いけたー! ということで、下記サイトを参考にしてpipを試す。
https://www.python.jp/install/macos/pip.html

$ python3.9 -m pip install pillow
Collecting pillow
  Downloading Pillow-8.0.1-cp39-cp39-macosx_10_10_x86_64.whl (2.2 MB)
     |████████████████████████████████| 2.2 MB 3.7 MB/s 
Installing collected packages: pillow
Successfully installed pillow-8.0.1
WARNING: You are using pip version 20.3.1; however, version 20.3.3 is available.
You should consider upgrading via the '/usr/local/opt/python@3.9/bin/python3.9 -m pip install --upgrade pip' command.

といわれるので、御意。

$ python3.9 -m pip install --upgrade pip
Requirement already satisfied: pip in /usr/local/lib/python3.9/site-packages (20.3.1)
Collecting pip
  Downloading pip-20.3.3-py2.py3-none-any.whl (1.5 MB)
     |████████████████████████████████| 1.5 MB 6.2 MB/s 
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 20.3.1
    Uninstalling pip-20.3.1:
      Successfully uninstalled pip-20.3.1
Successfully installed pip-20.3.3

上記サイトに従って、いったんpillowはアンインストール

$ python3.9 -m pip uninstall pillow
Found existing installation: Pillow 8.0.1
Uninstalling Pillow-8.0.1:
  Would remove:
    /usr/local/lib/python3.9/site-packages/PIL/*
    /usr/local/lib/python3.9/site-packages/Pillow-8.0.1.dist-info/*
Proceed (y/n)? y
  Successfully uninstalled Pillow-8.0.1

これでよいのだな。

感想

  • 「macOSに入っているpythonを使わない」というのがめちゃくちゃシンプルでスッキリした
  • ここでは書かなかったけれど、「venvを使う」というのもシンプルで、すごくスッキリした

リソース

macOS環境のPython:https://www.python.jp/install/macos/index.html
macOS環境のPython - pip :https://www.python.jp/install/macos/pip.html

ほとんど↑に書いてある。この記事はいわば「つくれぽ」。

環境

Python 3.9.1 (Dec 28 2020, 11:25:16)
macOS BigSur バージョン 11.1
MacBook Pro (13-inch, 2020, Four Thunderbolt 3 ports)

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