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Genetic generators

Bases: Generator

Source code in xopt/generators/ga/cnsga.py
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class CNSGAGenerator(Generator):
    name = "cnsga"
    supports_multi_objective: bool = True
    population_size: int = Field(64, description="Population size")
    crossover_probability: confloat(ge=0, le=1) = Field(
        0.9, description="Crossover probability"
    )
    mutation_probability: confloat(ge=0, le=1) = Field(
        1.0, description="Mutation probability"
    )
    population_file: Optional[str] = Field(
        None, description="Population file to load (CSV format)"
    )
    output_path: Optional[str] = Field(
        None, description="Output path for population " "files"
    )
    _children: List[Dict] = PrivateAttr([])
    _offspring: Optional[pd.DataFrame] = PrivateAttr(None)
    population: Optional[pd.DataFrame] = Field(None)

    model_config = ConfigDict(extra="allow")

    def __init__(self, **kwargs):
        super().__init__(**kwargs)

        self._loaded_population = (
            None  # use these to generate children until the first pop is made
        )

        # DEAP toolbox (internal)
        self._toolbox = cnsga_toolbox(self.vocs, selection="auto")

        if self.population_file is not None:
            self.load_population_csv(self.population_file)

        if self.output_path is not None:
            assert os.path.isdir(self.output_path), "Output directory does not exist"

        # if data is not None:
        #    self.population = cnsga_select(data, n_pop, vocs, self.toolbox)

    def create_children(self) -> List[Dict]:
        # No population, so create random children
        if self.population is None:
            # Special case when pop is loaded from file
            if self._loaded_population is None:
                return self.vocs.random_inputs(self.n_pop, include_constants=False)
            else:
                pop = self._loaded_population
        else:
            pop = self.population

        # Use population to create children
        inputs = cnsga_variation(
            pop,
            self.vocs,
            self._toolbox,
            crossover_probability=self.crossover_probability,
            mutation_probability=self.mutation_probability,
        )
        return inputs.to_dict(orient="records")

    def add_data(self, new_data: pd.DataFrame):
        if new_data is not None:
            self._offspring = pd.concat([self._offspring, new_data])

            # Next generation
            if len(self._offspring) >= self.n_pop:
                candidates = pd.concat([self.population, self._offspring])
                self.population = cnsga_select(
                    candidates, self.n_pop, self.vocs, self._toolbox
                )

                if self.output_path is not None:
                    self.write_offspring()
                    self.write_population()

                self._children = []  # reset children
                self._offspring = None  # reset offspring

    def generate(self, n_candidates) -> list[dict]:
        """
        generate `n_candidates` candidates

        """

        # Make sure we have enough children to fulfill the request
        while len(self._children) < n_candidates:
            self._children.extend(self.create_children())

        return [self._children.pop() for _ in range(n_candidates)]

    def write_offspring(self, filename=None):
        """
        Write the current offspring to a CSV file.

        Similar to write_population
        """
        if self._offspring is None:
            logger.warning("No offspring to write")
            return

        if filename is None:
            filename = f"{self.name}_offspring_{xopt.utils.isotime(include_microseconds=True)}.csv"
            filename = os.path.join(self.output_path, filename)

        self._offspring.to_csv(filename, index_label="xopt_index")

    def write_population(self, filename=None):
        """
        Write the current population to a CSV file.

        Similar to write_offspring
        """
        if self.population is None:
            logger.warning("No population to write")
            return

        if filename is None:
            filename = f"{self.name}_population_{xopt.utils.isotime(include_microseconds=True)}.csv"
            filename = os.path.join(self.output_path, filename)

        self.population.to_csv(filename, index_label="xopt_index")

    def load_population_csv(self, filename):
        """
        Read a population from a CSV file.
        These will be reverted back to children for re-evaluation.
        """
        pop = pd.read_csv(filename, index_col="xopt_index")
        self._loaded_population = pop
        # This is a list of dicts
        self._children = self.vocs.convert_dataframe_to_inputs(
            pop[self.vocs.variable_names], include_constants=False
        ).to_dict(orient="records")
        logger.info(f"Loaded population of len {len(pop)} from file: {filename}")

    @property
    def n_pop(self):
        """
        Convenience name for `options.population_size`
        """
        return self.population_size

n_pop property

Convenience name for options.population_size

generate(n_candidates)

generate n_candidates candidates

Source code in xopt/generators/ga/cnsga.py
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def generate(self, n_candidates) -> list[dict]:
    """
    generate `n_candidates` candidates

    """

    # Make sure we have enough children to fulfill the request
    while len(self._children) < n_candidates:
        self._children.extend(self.create_children())

    return [self._children.pop() for _ in range(n_candidates)]

load_population_csv(filename)

Read a population from a CSV file. These will be reverted back to children for re-evaluation.

Source code in xopt/generators/ga/cnsga.py
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def load_population_csv(self, filename):
    """
    Read a population from a CSV file.
    These will be reverted back to children for re-evaluation.
    """
    pop = pd.read_csv(filename, index_col="xopt_index")
    self._loaded_population = pop
    # This is a list of dicts
    self._children = self.vocs.convert_dataframe_to_inputs(
        pop[self.vocs.variable_names], include_constants=False
    ).to_dict(orient="records")
    logger.info(f"Loaded population of len {len(pop)} from file: {filename}")

write_offspring(filename=None)

Write the current offspring to a CSV file.

Similar to write_population

Source code in xopt/generators/ga/cnsga.py
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def write_offspring(self, filename=None):
    """
    Write the current offspring to a CSV file.

    Similar to write_population
    """
    if self._offspring is None:
        logger.warning("No offspring to write")
        return

    if filename is None:
        filename = f"{self.name}_offspring_{xopt.utils.isotime(include_microseconds=True)}.csv"
        filename = os.path.join(self.output_path, filename)

    self._offspring.to_csv(filename, index_label="xopt_index")

write_population(filename=None)

Write the current population to a CSV file.

Similar to write_offspring

Source code in xopt/generators/ga/cnsga.py
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def write_population(self, filename=None):
    """
    Write the current population to a CSV file.

    Similar to write_offspring
    """
    if self.population is None:
        logger.warning("No population to write")
        return

    if filename is None:
        filename = f"{self.name}_population_{xopt.utils.isotime(include_microseconds=True)}.csv"
        filename = os.path.join(self.output_path, filename)

    self.population.to_csv(filename, index_label="xopt_index")