report.Expression

class Expression

Bases: GenericOperation

Represents a mathematical expression to be evaluated on simulation result data.

This operation allows for defining and calculating custom expressions using variables extracted from simulation results. The results of the expression evaluation can be added as a new column to a dataframe for further analysis.

Example

expr = Expression(expr=”totalCD * area”) result = expr.calculate(data, case, cases, variables, new_variable_name)

Raises:

• ValueError – If variables in the expression are missing from the dataframe or if the expression cannot be evaluated due to syntax or other issues.

• NotImplementedError – If the data type is unsupported by the calculate method.

Attributes

expr: str

The mathematical expression to evaluate. It should be written in a syntax compatible with the numexpr library, using variable names that correspond to columns in the dataframe or user-defined variables.

Additional Constructors

classmethod from_file(filename)

Loads a Flow360BaseModel from .json, or .yaml file.

Parameters:

filename (str) – Full path to the .yaml or .json file to load the Flow360BaseModel from.

Returns:

An instance of the component class calling load.

Return type:

Flow360BaseModel

Example

>>> params = Flow360BaseModel.from_file(filename='folder/sim.json') 

Methods

classmethod get_variables(expr)

Parses the given expression and returns a set of variable names used in it.

classmethod evaluate_expression(df, expr, variables, new_variable_name, case)

Evaluates the given expression on the provided dataframe, using the specified variables. The result is added as a new column in the dataframe.

Parameters:

variables (List[Variable])

calculate(data, case, cases, variables, new_variable_name)

Executes the expression evaluation for the given simulation data and returns the result.

help(methods=False)

Prints message describing the fields and methods of a Flow360BaseModel.

Parameters:

methods (bool = False) – Whether to also print out information about object’s methods.

Return type:

None

Example

>>> params.help(methods=True) 

to_file(filename, **kwargs)

Exports Flow360BaseModel instance to .json or .yaml file

Parameters:

filename (str) – Full path to the .json or .yaml or file to save the Flow360BaseModel to.

Return type:

None

Example

>>> params.to_file(filename='folder/flow360.json')