black formatted codebase with pre-commit files

.pre-commit-config.yaml

@@ -0,0 +1,12 @@
+repos:
+  - repo: https://github.com/python/black
+    rev: 19.10b0
+    hooks:
+        - id: black
+          language_version: python3.7
+
+  - repo: https://gitlab.com/pycqa/flake8
+    rev: 3.7.7
+    hooks:
+        - id: flake8
+          args: [--append-config=tox.ini]

.travis.yml

@@ -86,8 +86,10 @@ jobs:
     - stage: Lint check
       python: "3.7"
       before_install: # Nothing to do
-      install: pip install flake8
-      script: flake8
+      install: pip install flake8 black
+      script:
+        - flake8 .
+        - black .
       after_success: # Nothing to do
 
     # GitHub Pages Deployment: https://docs.travis-ci.com/user/deployment/pages/

CONTRIBUTING.md

@@ -17,6 +17,47 @@ In both cases, you will also need to code some tests to ensure the correct behav
 
 New code should be compatible with Python 3.X versions. Once you finish implementing a feature or bugfix and tests, please run lint checking and tests:
 
+#### pre-commit
+To ensure the codebase complies with a style guide, we use [black](https://black.readthedocs.io/en/stable/) and [flake8](https://flake8.pycqa.org/en/latest/) to format and check codebase for compliance with PEP8. 
+
+To automate the process, we have configured the repo with [pre-commit hooks](https://pre-commit.com/) to use black to autoformat the staged files to ensure every commit complies with a style guide. This requires some setup, which is described below:
+
+1. Install pre-commit in your python environment.
+2. Run pre-commit install that configures a virtual environment to invoke black and flake8 on commits.
+
+```bash
+pip install pre-commit
+pre-commit install
+```
+
+3. When files are committed:
+    - If the stages files are not compliant with black, black will autoformat the staged files. If this were to happen, files should be staged and committed again. See example code below.
+    - If the staged files are not compliant with flake8, errors will be raised. These errors should be fixed and the files should be committed again. See example code below.
+
+```bash
+git add .
+git commit -m "Added awesome feature"
+# DONT'T WORRY IF ERRORS ARE RAISED.
+# YOUR CODE IS NOT COMPLIANT WITH FLAKE8 or BLACK
+# Fix any flake8 errors by following their suggestions
+# black will automatically format the files so they might look different, but you'll need to stage the files again for committing
+# After fixing any flake8 errors
+git add .
+git commit -m "Added feature"
+```
+
+#### Formatting Code without pre-commit
+If you choose not to use pre-commit, you can take advantage of IDE extensions configured to black format or invoke black manually to format files and commit them.
+
+```bash
+pip install black
+black .
+# This should autoformat the files
+git add .
+git commit -m "....."
+```
+
+
 #### Run lint checking
 ```bash
 flake8 ignite/ tests/ examples/

docs/source/conf.py

@@ -14,28 +14,29 @@
 #
 import os
 import sys
-sys.path.insert(0, os.path.abspath('../..'))
+
+sys.path.insert(0, os.path.abspath("../.."))
 import ignite
 import pytorch_sphinx_theme
 
 # -- Project information -----------------------------------------------------
 
-project = 'ignite'
-copyright = '2019, Torch Contributors'
-author = 'Torch Contributors'
+project = "ignite"
+copyright = "2019, Torch Contributors"
+author = "Torch Contributors"
 
 # The short X.Y version
 try:
-    version = os.environ['code_version']
-    if 'master' in version:
-        version = 'master (' + ignite.__version__ + ')'
+    version = os.environ["code_version"]
+    if "master" in version:
+        version = "master (" + ignite.__version__ + ")"
     else:
-        version = version.replace('v', '')
+        version = version.replace("v", "")
 except KeyError:
     version = ignite.__version__
 
 # The full version, including alpha/beta/rc tags
-release = 'master'
+release = "master"
 
 
 # -- General configuration ---------------------------------------------------
@@ -48,27 +49,27 @@
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
-    'sphinx.ext.autosummary',
-    'sphinx.ext.doctest',
-    'sphinx.ext.intersphinx',
-    'sphinx.ext.todo',
-    'sphinx.ext.coverage',
-    'sphinx.ext.mathjax',
-    'sphinx.ext.napoleon',
-    'sphinx.ext.viewcode'
+    "sphinx.ext.autosummary",
+    "sphinx.ext.doctest",
+    "sphinx.ext.intersphinx",
+    "sphinx.ext.todo",
+    "sphinx.ext.coverage",
+    "sphinx.ext.mathjax",
+    "sphinx.ext.napoleon",
+    "sphinx.ext.viewcode",
 ]
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
+templates_path = ["_templates"]
 
 # The suffix(es) of source filenames.
 # You can specify multiple suffix as a list of string:
 #
 # source_suffix = ['.rst', '.md']
-source_suffix = '.rst'
+source_suffix = ".rst"
 
 # The master toctree document.
-master_doc = 'index'
+master_doc = "index"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
@@ -83,25 +84,25 @@
 exclude_patterns = []
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = "sphinx"
 
 
 # -- Options for HTML output -------------------------------------------------
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'pytorch_sphinx_theme'
+html_theme = "pytorch_sphinx_theme"
 html_theme_path = [pytorch_sphinx_theme.get_html_theme_path()]
 
 html_theme_options = {
-    'canonical_url': 'https://pytorch.org/ignite/index.html',
-    'collapse_navigation': False,
-    'display_version': True,
-    'logo_only': True,
+    "canonical_url": "https://pytorch.org/ignite/index.html",
+    "collapse_navigation": False,
+    "display_version": True,
+    "logo_only": True,
 }
 
-html_logo = '_static/img/ignite-logo-dark.svg'
+html_logo = "_static/img/ignite-logo-dark.svg"
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
@@ -112,21 +113,21 @@
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static', '_templates/_static']
+html_static_path = ["_static", "_templates/_static"]
 
 html_context = {
-    'css_files': [
+    "css_files": [
         # 'https://fonts.googleapis.com/css?family=Lato',
         # '_static/css/pytorch_theme.css'
-        '_static/css/ignite_theme.css'
+        "_static/css/ignite_theme.css"
     ],
 }
 
 
 # -- Options for HTMLHelp output ---------------------------------------------
 
 # Output file base name for HTML help builder.
-htmlhelp_basename = 'ignitedoc'
+htmlhelp_basename = "ignitedoc"
 
 
 # -- Options for LaTeX output ------------------------------------------------
@@ -135,15 +136,12 @@
     # The paper size ('letterpaper' or 'a4paper').
     #
     # 'papersize': 'letterpaper',
-
     # The font size ('10pt', '11pt' or '12pt').
     #
     # 'pointsize': '10pt',
-
     # Additional stuff for the LaTeX preamble.
     #
     # 'preamble': '',
-
     # Latex figure (float) alignment
     #
     # 'figure_align': 'htbp',
@@ -153,19 +151,15 @@
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-    (master_doc, 'ignite.tex', 'ignite Documentation',
-     'Torch Contributors', 'manual'),
+    (master_doc, "ignite.tex", "ignite Documentation", "Torch Contributors", "manual"),
 ]
 
 
 # -- Options for manual page output ------------------------------------------
 
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
-man_pages = [
-    (master_doc, 'ignite', 'ignite Documentation',
-     [author], 1)
-]
+man_pages = [(master_doc, "ignite", "ignite Documentation", [author], 1)]
 
 
 # -- Options for Texinfo output ----------------------------------------------
@@ -174,9 +168,15 @@
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-    (master_doc, 'ignite', 'ignite Documentation',
-     author, 'ignite', 'One line description of project.',
-     'Miscellaneous'),
+    (
+        master_doc,
+        "ignite",
+        "ignite Documentation",
+        author,
+        "ignite",
+        "One line description of project.",
+        "Miscellaneous",
+    ),
 ]
 
 
@@ -185,7 +185,7 @@
 # -- Options for intersphinx extension ---------------------------------------
 
 # Example configuration for intersphinx: refer to the Python standard library.
-intersphinx_mapping = {'https://docs.python.org/': None}
+intersphinx_mapping = {"https://docs.python.org/": None}
 
 # -- Options for todo extension ----------------------------------------------
 

examples/contrib/cifar10/fastresnet.py

@@ -1,4 +1,3 @@
-
 # Network from https://github.com/davidcpage/cifar10-fast
 # Adapted to python < 3.6
 
@@ -9,8 +8,7 @@ def fastresnet():
     return FastResnet()
 
 
-def batch_norm(num_channels, bn_bias_init=None, bn_bias_freeze=False,
-               bn_weight_init=None, bn_weight_freeze=False):
+def batch_norm(num_channels, bn_bias_init=None, bn_bias_freeze=False, bn_weight_init=None, bn_weight_freeze=False):
     m = nn.BatchNorm2d(num_channels)
     if bn_bias_init is not None:
         m.bias.data.fill_(bn_bias_init)
@@ -32,10 +30,9 @@ def seq_conv_bn(in_channels, out_channels, conv_kwargs, bn_kwargs):
     if "bias" not in conv_kwargs:
         conv_kwargs["bias"] = False
     return nn.Sequential(
-        nn.Conv2d(in_channels, out_channels,
-                  kernel_size=3, **conv_kwargs),
+        nn.Conv2d(in_channels, out_channels, kernel_size=3, **conv_kwargs),
         batch_norm(out_channels, **bn_kwargs),
-        nn.ReLU(inplace=True)
+        nn.ReLU(inplace=True),
     )
 
 
@@ -47,24 +44,19 @@ def conv_bn_elu(in_channels, out_channels, conv_kwargs, bn_kwargs, alpha=1.0):
     if "bias" not in conv_kwargs:
         conv_kwargs["bias"] = False
     return nn.Sequential(
-        nn.Conv2d(in_channels, out_channels,
-                  kernel_size=3, **conv_kwargs),
+        nn.Conv2d(in_channels, out_channels, kernel_size=3, **conv_kwargs),
         batch_norm(out_channels, **bn_kwargs),
-        nn.ELU(alpha=alpha, inplace=True)
+        nn.ELU(alpha=alpha, inplace=True),
     )
 
 
 class Flatten(nn.Module):
-
     def forward(self, x):
         return x.view(x.size(0), x.size(1))
 
 
 class FastResnet(nn.Module):
-
-    def __init__(self, conv_kwargs=None, bn_kwargs=None,
-                 conv_bn_fn=seq_conv_bn,
-                 final_weight=0.125):
+    def __init__(self, conv_kwargs=None, bn_kwargs=None, conv_bn_fn=seq_conv_bn, final_weight=0.125):
         super(FastResnet, self).__init__()
 
         conv_kwargs = {} if conv_kwargs is None else conv_kwargs
@@ -75,34 +67,22 @@ def __init__(self, conv_kwargs=None, bn_kwargs=None,
         self.layer1 = nn.Sequential(
             conv_bn_fn(64, 128, conv_kwargs, bn_kwargs),
             nn.MaxPool2d(kernel_size=2),
-            IdentityResidualBlock(128, 128, conv_kwargs, bn_kwargs, conv_bn_fn=conv_bn_fn)
+            IdentityResidualBlock(128, 128, conv_kwargs, bn_kwargs, conv_bn_fn=conv_bn_fn),
         )
 
-        self.layer2 = nn.Sequential(
-            conv_bn_fn(128, 256, conv_kwargs, bn_kwargs),
-            nn.MaxPool2d(kernel_size=2)
-        )
+        self.layer2 = nn.Sequential(conv_bn_fn(128, 256, conv_kwargs, bn_kwargs), nn.MaxPool2d(kernel_size=2))
 
         self.layer3 = nn.Sequential(
             conv_bn_fn(256, 512, conv_kwargs, bn_kwargs),
             nn.MaxPool2d(kernel_size=2),
-            IdentityResidualBlock(512, 512, conv_kwargs, bn_kwargs, conv_bn_fn=conv_bn_fn)
+            IdentityResidualBlock(512, 512, conv_kwargs, bn_kwargs, conv_bn_fn=conv_bn_fn),
         )
 
-        self.head = nn.Sequential(
-            nn.AdaptiveMaxPool2d(1),
-            Flatten(),
-        )
+        self.head = nn.Sequential(nn.AdaptiveMaxPool2d(1), Flatten(),)
 
         self.final_weight = final_weight
 
-        self.features = nn.Sequential(
-            self.prep,
-            self.layer1,
-            self.layer2,
-            self.layer3,
-            self.head
-        )
+        self.features = nn.Sequential(self.prep, self.layer1, self.layer2, self.layer3, self.head)
 
         self.classifier = nn.Linear(512, 10, bias=False)
 
@@ -115,9 +95,7 @@ def forward(self, x):
 
 
 class IdentityResidualBlock(nn.Module):
-
-    def __init__(self, in_channels, out_channels, conv_kwargs, bn_kwargs,
-                 conv_bn_fn=seq_conv_bn):
+    def __init__(self, in_channels, out_channels, conv_kwargs, bn_kwargs, conv_bn_fn=seq_conv_bn):
         super(IdentityResidualBlock, self).__init__()
         self.conv1 = conv_bn_fn(in_channels, out_channels, conv_kwargs, bn_kwargs)
         self.conv2 = conv_bn_fn(out_channels, out_channels, conv_kwargs, bn_kwargs)