Switch to using black for code formatting

.pylintrc

@@ -74,7 +74,8 @@ disable=no-self-use,        # disabled as it is too verbose
     unnecessary-pass,   # allow for methods with just "pass", for clarity
     no-else-return,     # relax "elif" after a clause with a return
     docstring-first-line-empty, # relax docstring style
-    import-outside-toplevel
+    import-outside-toplevel,
+    bad-continuation, bad-whitespace # differences of opinion with black
 
 
 
@@ -215,7 +216,7 @@ max-nested-blocks=5
 [FORMAT]
 
 # Maximum number of characters on a single line.
-max-line-length=100
+max-line-length=105
 
 # Regexp for a line that is allowed to be longer than the limit.
 ignore-long-lines=^\s*(# )?<?https?://\S+>?$

CONTRIBUTING.md

@@ -33,6 +33,10 @@ please ensure that:
    make style 
    ```
    from the root of the Optimization repository clone for lint and style conformance checks.
+
+   If your code fails the local style checks (specifically the black
+   code formatting check) you can use `make black` to automatically
+   fix update the code formatting.
 
    For unit testing please see [Testing](#testing) section below.
 

Makefile

@@ -46,7 +46,10 @@ mypy:
 	mypy qiskit_optimization test tools
 
 style:
-	pycodestyle qiskit_optimization test tools
+	black --check qiskit_optimization test tools
+
+black:
+	black qiskit_optimization test tools
 
 test:
 	python -m unittest discover -v test

qiskit_optimization/__init__.py

@@ -87,8 +87,4 @@
 from .exceptions import QiskitOptimizationError
 from .problems.quadratic_program import QuadraticProgram
 
-__all__ = ['__version__',
-           'QuadraticProgram',
-           'QiskitOptimizationError',
-           'INFINITY'
-           ]
+__all__ = ["__version__", "QuadraticProgram", "QiskitOptimizationError", "INFINITY"]

qiskit_optimization/algorithms/__init__.py

@@ -62,29 +62,64 @@
 
 """
 
-from .admm_optimizer import ADMMOptimizer, ADMMOptimizationResult, ADMMState, ADMMParameters
+from .admm_optimizer import (
+    ADMMOptimizer,
+    ADMMOptimizationResult,
+    ADMMState,
+    ADMMParameters,
+)
 from .cobyla_optimizer import CobylaOptimizer
 from .cplex_optimizer import CplexOptimizer
-from .goemans_williamson_optimizer import (GoemansWilliamsonOptimizer,
-                                           GoemansWilliamsonOptimizationResult)
+from .goemans_williamson_optimizer import (
+    GoemansWilliamsonOptimizer,
+    GoemansWilliamsonOptimizationResult,
+)
 from .grover_optimizer import GroverOptimizer, GroverOptimizationResult
-from .minimum_eigen_optimizer import (MinimumEigenOptimizer, MinimumEigenOptimizationResult)
+from .minimum_eigen_optimizer import (
+    MinimumEigenOptimizer,
+    MinimumEigenOptimizationResult,
+)
 from .multistart_optimizer import MultiStartOptimizer
-from .optimization_algorithm import (OptimizationAlgorithm, OptimizationResult,
-                                     OptimizationResultStatus, SolutionSample)
-from .recursive_minimum_eigen_optimizer import (RecursiveMinimumEigenOptimizer,
-                                                RecursiveMinimumEigenOptimizationResult,
-                                                IntermediateResult)
+from .optimization_algorithm import (
+    OptimizationAlgorithm,
+    OptimizationResult,
+    OptimizationResultStatus,
+    SolutionSample,
+)
+from .recursive_minimum_eigen_optimizer import (
+    RecursiveMinimumEigenOptimizer,
+    RecursiveMinimumEigenOptimizationResult,
+    IntermediateResult,
+)
 from .slsqp_optimizer import SlsqpOptimizer, SlsqpOptimizationResult
-from .warm_start_qaoa_optimizer import (BaseAggregator, MeanAggregator, WarmStartQAOAFactory,
-                                        WarmStartQAOAOptimizer)
+from .warm_start_qaoa_optimizer import (
+    BaseAggregator,
+    MeanAggregator,
+    WarmStartQAOAFactory,
+    WarmStartQAOAOptimizer,
+)
 
-__all__ = ["ADMMOptimizer", "OptimizationAlgorithm", "OptimizationResult",
-           "OptimizationResultStatus", "BaseAggregator",
-           "CplexOptimizer", "CobylaOptimizer", "GoemansWilliamsonOptimizer",
-           "GoemansWilliamsonOptimizationResult", "GroverOptimizer", "GroverOptimizationResult",
-           "MeanAggregator",
-           "MinimumEigenOptimizer", "MinimumEigenOptimizationResult",
-           "RecursiveMinimumEigenOptimizer", "RecursiveMinimumEigenOptimizationResult",
-           "IntermediateResult", "SlsqpOptimizer", "SlsqpOptimizationResult", "SolutionSample",
-           "WarmStartQAOAOptimizer", "WarmStartQAOAFactory"]
+__all__ = [
+    "ADMMOptimizer",
+    "OptimizationAlgorithm",
+    "OptimizationResult",
+    "OptimizationResultStatus",
+    "BaseAggregator",
+    "CplexOptimizer",
+    "CobylaOptimizer",
+    "GoemansWilliamsonOptimizer",
+    "GoemansWilliamsonOptimizationResult",
+    "GroverOptimizer",
+    "GroverOptimizationResult",
+    "MeanAggregator",
+    "MinimumEigenOptimizer",
+    "MinimumEigenOptimizationResult",
+    "RecursiveMinimumEigenOptimizer",
+    "RecursiveMinimumEigenOptimizationResult",
+    "IntermediateResult",
+    "SlsqpOptimizer",
+    "SlsqpOptimizationResult",
+    "SolutionSample",
+    "WarmStartQAOAOptimizer",
+    "WarmStartQAOAFactory",
+]