add pre-commit

.flake8

@@ -0,0 +1,5 @@
+[flake8]
+ignore = E203, E266, E501, W503, F403, F401, C901
+max-line-length = 127
+max-complexity = 10
+select = B,C,E,F,W,T4,B9

.github/workflows/python-lint.yml

@@ -0,0 +1,34 @@
+name: Python Linting
+
+on:
+  pull_request:
+    branches:
+      - main
+      - master
+
+jobs:
+  flake8:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.8'
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install flake8
+
+    - name: Pre-Commit
+      uses: pre-commit/[email protected]
+
+    - name: Run flake8
+      run: |
+        # stop the build if there are Python syntax errors or undefined names
+        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
+        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics

.pre-commit-config.yaml

@@ -0,0 +1,47 @@
+# Ignore test linting to avoid conflicting changes to version stability.
+exclude: |
+    (?x)^(
+      demo_data/|
+      templates/|
+      static/|
+      fig/|
+    )
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.1.0
+    hooks:
+      - id: check-added-large-files
+      - id: check-ast
+      - id: check-byte-order-marker
+      - id: check-case-conflict
+      - id: check-json
+      - id: check-merge-conflict
+      - id: check-symlinks
+      - id: check-yaml
+        args: ["--unsafe"]
+      - id: destroyed-symlinks
+      - id: detect-private-key
+      - id: end-of-file-fixer
+      - id: requirements-txt-fixer
+      - id: trailing-whitespace
+      - id: fix-encoding-pragma
+        args: [--remove]
+      - id: mixed-line-ending
+        args: [--fix=lf]
+  - repo: https://github.com/pycqa/flake8
+    rev: 3.7.9
+    hooks:
+      - id: flake8
+  - repo: https://github.com/psf/black
+    rev: 22.3.0
+    hooks:
+      - id: black
+  - repo: https://github.com/codespell-project/codespell
+    rev: v2.2.4
+    hooks:
+      - id: codespell
+        exclude: >
+          (?x)^(
+              .*\.json|.*\.ipynb
+          )$
+        args: [--check-filenames, -L=fpt, '--ignore-regex=.{1024}|.*codespell-ignore.*']