NRWAL.handlers.equations.Equation

class Equation(eqn, name=None, default_variables=None)[source]

Bases: object

Class to handle and evaluate a single wind cost equation string.

Parameters:

eqn (str | int | float) – Cost equation in a string representation or a single number e.g.: “-34.80 * depth ** 2 + 207619.80 * depth + 221197699.89”
name (str | None) – Optional equation name / key for string formatting
default_variables (dict) – Optional dictionary of default variables accessible to this Equation object. These inputs can still be overwritten at runtime.

Methods

`eval`	Alias for evaluate().
`evaluate`	Evaluate the equation string and return the result
`is_equation`	Check if an expression is an equation to be handled by this framework.
`is_method`	Check if a string is a numpy/pandas or python builtin method
`is_num`	Check if a string is a number
`is_variable`	Check if a string is a variable name without any constants, operators, or arithmetic expressions
`parse_variables`	Parse variable names from an expression string.
`replace_equation`	Replace the expression of this equation with a new one.
`set_default_variables`	Set default variables available to this Equation object.
`verify_no_self_reference`	Verify that the equation does not reference itself.

Attributes

`ILLEGAL`
`default_variables`	Get a dictionary of default variables from a variables.yaml file accessible to this object
`full`	Get the full equation string without any pretty formatting.
`variables`	Get a unique sorted list names of all input variables that the Equation needs.

verify_no_self_reference()[source]

Verify that the equation does not reference itself.

Raises:: ValueError – If a reference to the equation name is found in its variables.

replace_equation(new_eqn)[source]

Replace the expression of this equation with a new one.

This method returns a new Equation instance that replaces the existing equation expression with the new one supplied by the user, keeping the equation name and default variables unchanged.

Parameters:: new_eqn (str) – String representation of the new Equation instance.
Returns:: Equation – A new Equation instance with the same name and default values as the old Equation but with the new equation expression.

__add__(other)[source]

Add another equation to this instance of Equation (self) and return a new Equation object that evaluates the sum of the two equations

Parameters:: other (Equation | str | int | float) – Another Equation object or simple string representation of an equation to add to this instance of Equation (self).
Returns:: out (Equation) – A new Equation instance with this instance of Equation (self) summed with the input Equation.

__mul__(other)[source]

Multiply another equation by this instance of Equation (self) and return a new Equation object that evaluates the product of the two equations

Parameters:: other (Equation | str | int | float) – Another Equation object or simple string representation of an equation to multiply by this instance of Equation (self).
Returns:: out (Equation) – A new Equation instance with this instance of Equation (self) multiplied by the input Equation.

set_default_variables(var_dict)[source]

Set default variables available to this Equation object.

Parameters:: var_dict (dict | None) – Default variables namespace. These variables can always be overwritten when Equation.evaluate() is called.

static is_num(s)[source]: Check if a string is a number

static is_method(s)[source]: Check if a string is a numpy/pandas or python builtin method

classmethod is_variable(s)[source]: Check if a string is a variable name without any constants, operators, or arithmetic expressions

property full: Get the full equation string without any pretty formatting.

property default_variables

Get a dictionary of default variables from a variables.yaml file accessible to this object

Returns:: dict

classmethod parse_variables(expression)[source]: Parse variable names from an expression string.

property variables

Get a unique sorted list names of all input variables that the Equation needs. This will return an empty list if the equation has no variables.

Returns:: list

classmethod is_equation(expression)[source]

Check if an expression is an equation to be handled by this framework.

Parameters:: expression (str | int | float) – Expression to be checked as an equation or not.
Returns:: check (bool) – True if the expression is an equation that can be handled by this framework.

eval(**kwargs)[source]: Alias for evaluate().

evaluate(**kwargs)[source]

Evaluate the equation string and return the result

Parameters:: kwargs (dict) – Keyword arguments setting variables of the equation. Note that this is **kwargs so this method can be run in either of these syntaxes:

Equation.evaluate(input1=10, input2=20) Equation.evaluate(**{‘input1’: 10, ‘input2’: 20})
Returns:: out (float | np.ndarray) – Evaluated output of this equation object.