filter

FilterExpr

Bases: ABC

Expression to be used in a Filter transform.

get() abstractmethod

Get the polars expression for this filter.

Source code in src/flowcean/transforms/filter.py

@abstractmethod
def get(self) -> pl.Expr:
    """Get the polars expression for this filter."""

Filter(expression)

Bases: Transform

Filter an environment based on one or multiple expressions.

This transform allows to filter an environment based on or multiple boolean expressions. Assuming the input environment is given by

t	N	x
1	10	0
2	12	1
3	5	2
4	15	1
5	17	0

The following transformation can be used to filter the environment so that the result contains only records where x=1:

    Filter("x == 1")

The result dataset after applying the transform will be

t	N	x
2	15	1
4	12	1

To only get records where x=1 and t > 3 the filter expression

Filter(And(["x == 1", "t > 3"]))

can be used.

To filter all records where x=1 and t > 3 or N < 15 use

Filter(And(["x == 1", Or(["t > 3", "N < 15"])]))

Initializes the Filter transform.

Parameters:

Name	Type	Description	Default
expression	str | FilterExpr	String or filter expression used to filter the environment. Records that do not match the expression are discarded. Standard comparison and mathematical operations are supported within the expressions. Features can be accessed by there name.	required

Source code in src/flowcean/transforms/filter.py

def __init__(
    self,
    expression: str | FilterExpr,
) -> None:
    """Initializes the Filter transform.

    Args:
        expression: String or filter expression used to filter the
            environment. Records that do not match the expression are
            discarded. Standard comparison and mathematical operations are
            supported within the expressions. Features can be accessed by
            there name.
    """
    if isinstance(expression, str):
        self.predicate = str_to_pl(expression)
    else:
        self.predicate = expression()