lsst.pipe.tasks.dataFrameActions._evalColumnExpression Namespace Reference

Classes
class	ExpressionParser

Functions
Type[DataFrameAction]	makeColumnExpressionAction (str className, str expr, Optional[Mapping[str, Union[DataFrameAction, Type[DataFrameAction]]]] exprDefaults=None, str docstring=None)

Variables
dictionary	OPERATORS
dictionary	EXTRA_MATH = {"cos": cos, "sin": sin, "cosh": cosh, "sinh": sinh, "log": log}

Function Documentation

makeColumnExpressionAction()

Type[DataFrameAction] lsst.pipe.tasks.dataFrameActions._evalColumnExpression.makeColumnExpressionAction	(	str	className,
		str	expr,
		Optional[Mapping[str, Union[DataFrameAction, Type[DataFrameAction]]]]	exprDefaults = None,
		str	docstring = None
	)

Definition at line 83 of file _evalColumnExpression.py.

                               ) -> Type[DataFrameAction]:
    node = ast.parse(expr, mode='eval')
 
    # gather the specified names
    names: Set[str] = set()
    for elm in ast.walk(node):
        if isinstance(elm, ast.Name):
            names.add(elm.id)
 
    # remove the known Math names
    names -= EXTRA_MATH.keys()
 
    fields: Mapping[str, ConfigurableActionField] = {}
    for name in names:
        if exprDefaults is not None and (value := exprDefaults.get(name)) is not None:
            kwargs = {"default": value}
        else:
            kwargs = {}
        fields[name] = ConfigurableActionField(doc=f"expression action {name}", **kwargs)
 
    # skip flake8 on N807 because this is a stand alone function, but it is
    # intended to be patched in as a method on a dynamically generated class
    def __call__(self, df: pd.DataFrame, **kwargs) -> pd.Series:  # noqa: N807
        values_map = {}
        for name in fields:
            values_map[name] = getattr(self, name)(df, **kwargs)
 
        parser = ExpressionParser(**values_map)
        return parser.visit(node.body)
 
    # create the function to look up the columns for the dynamically created action
    def columns(self) -> Iterable[str]:
        for name in fields:
            yield from getattr(self, name).columns
 
    dct: MutableMapping[str, Any] = {"__call__": __call__, "columns": property(columns)}
    if docstring is not None:
        dct['__doc__'] = docstring
    dct.update(**fields)
 
    return type(className, (DataFrameAction, ), dct)

Variable Documentation

EXTRA_MATH

dictionary lsst.pipe.tasks.dataFrameActions._evalColumnExpression.EXTRA_MATH = {"cos": cos, "sin": sin, "cosh": cosh, "sinh": sinh, "log": log}

Definition at line 43 of file _evalColumnExpression.py.

OPERATORS

dictionary lsst.pipe.tasks.dataFrameActions._evalColumnExpression.OPERATORS

Initial value:

=  {ast.Add: op.add, ast.Sub: op.sub, ast.Mult: op.mul,
             ast.Div: op.truediv, ast.Pow: op.pow, ast.BitXor: op.xor,
             ast.USub: op.neg}

Definition at line 39 of file _evalColumnExpression.py.