Use black Python format

azure-pipelines.yml

@@ -106,6 +106,10 @@ jobs:
     - bash: yarn
       displayName: 'Install Deps'
 
+    - bash: python -m pip install "black==20.8b1" flake8-black
+      condition: and(succeeded(), ne(variables['python.version'], '2.7'))
+      displayName: 'Install Python deps'
+
     - bash: yarn build_python  --ci $(python_flag) $(manylinux_flag)
       displayName: 'build'
       env:
@@ -248,7 +252,7 @@ jobs:
         displayName: "Which python"
 
       - script: |
-          python -m pip install delocate wheel numpy "pyarrow>=0.16.0,<1"
+          python -m pip install delocate wheel numpy "black==20.8b1" flake8-black "pyarrow>=0.16.0,<1"
         displayName: "Python deps"
 
       - script: npm install -g yarn

docker/python/manylinux2010/Dockerfile

@@ -36,10 +36,10 @@ RUN cp -arf /opt/python/cp38-cp38/* /usr/local/
 ENV PATH=/usr/local/bin:$PATH
 
 # Install dependencies
-RUN python2.7 -m pip install numpy scipy pybind11 cython codecov mock flake8 pytest pytest-cov traitlets ipywidgets faker psutil
-RUN python3.6 -m pip install numpy scipy pybind11 cython codecov mock flake8 pytest pytest-cov traitlets ipywidgets faker psutil
-RUN python3.7 -m pip install numpy scipy pybind11 cython codecov mock flake8 pytest pytest-cov traitlets ipywidgets faker psutil
-RUN python3.8 -m pip install numpy scipy pybind11 cython codecov mock flake8 pytest pytest-cov traitlets ipywidgets faker psutil
+RUN python2.7 -m pip install numpy scipy pybind11 cython codecov mock pytest pytest-cov traitlets ipywidgets faker psutil
+RUN python3.6 -m pip install numpy scipy pybind11 cython codecov mock black>=20 flake8-black pytest pytest-cov traitlets ipywidgets faker psutil
+RUN python3.7 -m pip install numpy scipy pybind11 cython codecov mock black>=20 flake8-black pytest pytest-cov traitlets ipywidgets faker psutil
+RUN python3.8 -m pip install numpy scipy pybind11 cython codecov mock black>=20 flake8-black pytest pytest-cov traitlets ipywidgets faker psutil
 
 # Install Auditwheel - not available on Python 2
 RUN python3.6 -m pip install --ignore-installed auditwheel

docker/python/manylinux2014/Dockerfile

@@ -34,9 +34,9 @@ RUN cp -arf /opt/python/cp38-cp38/* /usr/local/
 ENV PATH=/usr/local/bin:$PATH
 
 # Install dependencies
-RUN python3.6 -m pip install numpy scipy pybind11 cython codecov mock flake8 pytest pytest-cov traitlets ipywidgets faker psutil
-RUN python3.7 -m pip install numpy scipy pybind11 cython codecov mock flake8 pytest pytest-cov traitlets ipywidgets faker psutil
-RUN python3.8 -m pip install numpy scipy pybind11 cython codecov mock flake8 pytest pytest-cov traitlets ipywidgets faker psutil
+RUN python3.6 -m pip install numpy scipy pybind11 cython codecov mock "black==20.8b1" flake8-black pytest pytest-cov traitlets ipywidgets faker psutil
+RUN python3.7 -m pip install numpy scipy pybind11 cython codecov mock "black==20.8b1" flake8-black pytest pytest-cov traitlets ipywidgets faker psutil
+RUN python3.8 -m pip install numpy scipy pybind11 cython codecov mock "black==20.8b1" flake8-black pytest pytest-cov traitlets ipywidgets faker psutil
 
 # Install Auditwheel - not available on Python 2
 RUN python3.6 -m pip install --ignore-installed auditwheel

package.json

@@ -118,17 +118,17 @@
         "clean": "node scripts/clean.js",
         "start": "lerna run start --stream --scope",
         "precommit": "npm run lint",
-        "lint": "npm-run-all lint:* lint_python",
+        "lint": "npm-run-all lint:*",
         "lint:eslint": "eslint \"packages/*/src/**/*.js\" \"packages/*/test/**/*.js\" \"examples/*/*.js\"",
         "lint_:tslint": "eslint \"packages/*/src/**/*.ts\" \"packages/*/test/**/*.ts\" \"examples/*/*.ts\"",
-        "lint_python": "node scripts/lint_python.js",
+        "lint:python": "node scripts/lint_python.js",
         "fix:es": "npm run lint:eslint -- --fix",
         "fix:md": "prettier docs/md/*.md --prose-wrap=always --write",
         "fix:cpp": "node scripts/fix_cpp.js",
         "fix:less": "prettier --tab-width 4 --write packages/**/src/less/*.less",
         "fix:html": "html-beautify packages/**/src/html/*.html -r",
         "fix:json": "prettier --tab-width 4 --write **/package.json",
-        "fix_python": "node scripts/lint_python.js --fix",
+        "fix:python": "node scripts/lint_python.js --fix",
         "fix": "npm-run-all --silent fix:*",
         "toggle_puppeteer": "node scripts/toggle_puppeteer.js",
         "version": "python3 python/perspective/scripts/write_version.py && git add python/perspective/perspective/core/_version.py"

python/perspective/bench/__init__.py

@@ -8,4 +8,4 @@
 
 from bench import Benchmark, Suite, Runner
 
-__all__ = ["Benchmark", "Suite", "Runner"]
+__all__ = ["Benchmark", "Suite", "Runner"]

python/perspective/bench/bench.py

@@ -14,8 +14,13 @@
 import tornado
 from datetime import datetime
 from timeit import timeit
-sys.path.insert(1, os.path.join(os.path.dirname(__file__), '..'))
-from perspective import Table, PerspectiveManager, PerspectiveTornadoHandler  # noqa: E402
+
+sys.path.insert(1, os.path.join(os.path.dirname(__file__), ".."))
+from perspective import (
+    Table,
+    PerspectiveManager,
+    PerspectiveTornadoHandler,
+)  # noqa: E402
 
 logging.basicConfig(level=logging.INFO)
 
@@ -36,27 +41,26 @@ def virtualenv_exists(self):
 
     def activate_virtualenv(self):
         """Activates the virtualenv at `VIRTUALENV_PATH`."""
-        logging.info(
-            "Activating virtualenv at: `{}`".format(self._virtualenv_path))
+        logging.info("Activating virtualenv at: `{}`".format(self._virtualenv_path))
         subprocess.check_output(
-            "source {}/bin/activate".format(self._virtualenv_path),
-            shell=True)
+            "source {}/bin/activate".format(self._virtualenv_path), shell=True
+        )
         self._is_activated = True
 
     def create_virtualenv(self):
         """Clears the folder and creates a new virtualenv at
         `self._virtualenv_path`."""
         if self.virtualenv_exists():
-            logging.ERROR("Virtualenv already exists at: `{0}`".format(self._virtualenv_path))
+            logging.ERROR(
+                "Virtualenv already exists at: `{0}`".format(self._virtualenv_path)
+            )
             return
         logging.info("Creating virtualenv at: `{}`".format(self._virtualenv_path))
         venv.create(self._virtualenv_path, clear=True, with_pip=True)
 
     def deactivate_virtualenv(self):
         if self.virtualenv_exists() and self._is_activated:
-            subprocess.check_output(
-                "deactivate",
-                shell=True)
+            subprocess.check_output("deactivate", shell=True)
             logging.info("Virtualenv deactivated!")
             self._is_activated = False
 
@@ -67,7 +71,7 @@ class BenchmarkTornadoHandler(tornado.web.RequestHandler):
     def set_default_headers(self):
         self.set_header("Access-Control-Allow-Origin", "*")
         self.set_header("Access-Control-Allow-Headers", "x-requested-with")
-        self.set_header('Access-Control-Allow-Methods', 'POST, GET, OPTIONS')
+        self.set_header("Access-Control-Allow-Methods", "POST, GET, OPTIONS")
 
     def get(self):
         self.render("benchmark_hosted.html")
@@ -125,7 +129,8 @@ def register_benchmarks(self):
         This function must be implemented in all child classes of `Suite.`
         """
         raise NotImplementedError(
-                "Must implement `register_benchmarks` to run benchmark suite.")
+            "Must implement `register_benchmarks` to run benchmark suite."
+        )
 
     def before_all(self):
         pass
@@ -191,14 +196,17 @@ def host_results(self):
             return
         MANAGER = PerspectiveManager()
         MANAGER.host_table("benchmark_results", self._table)
-        application = tornado.web.Application([
-            (r"/", BenchmarkTornadoHandler),
-            # create a websocket endpoint that the client Javascript can access
-            (r"/websocket", PerspectiveTornadoHandler, {
-                "manager": MANAGER,
-                "check_origin": True
-            })
-        ])
+        application = tornado.web.Application(
+            [
+                (r"/", BenchmarkTornadoHandler),
+                # create a websocket endpoint that the client Javascript can access
+                (
+                    r"/websocket",
+                    PerspectiveTornadoHandler,
+                    {"manager": MANAGER, "check_origin": True},
+                ),
+            ]
+        )
         self._HOSTING = True
         application.listen(8888)
         logging.critical("Displaying results at http://localhost:8888")
@@ -221,22 +229,25 @@ def run_method(self, func, *args, **kwargs):
         `ITERATIONS`, returning a result row that can be fed into Perspective.
         """
         overall_result = {
-            k.replace("__BENCH__", ""):
-                v for (k, v) in func.__dict__.items() if "__BENCH__" in k
+            k.replace("__BENCH__", ""): v
+            for (k, v) in func.__dict__.items()
+            if "__BENCH__" in k
         }
 
         result = timeit(func, number=Runner.ITERATIONS) / Runner.ITERATIONS
         overall_result["__TIME__"] = result
         return overall_result
 
     def print_result(self, result):
-        print("{}::{} ({}):{:30}{:>30}".format(
-            result["group"],
-            result["name"],
-            result["version"],
-            "",
-            result["__TIME__"],
-        ))
+        print(
+            "{}::{} ({}):{:30}{:>30}".format(
+                result["group"],
+                result["name"],
+                result["version"],
+                "",
+                result["__TIME__"],
+            )
+        )
 
     def run(self, version):
         """Runs each benchmark function from the suite for n `ITERATIONS`,