tensorflow_probability/python/optimizer/differential_evolution.py
def _get_starting_population(initial_population,
                             initial_position,
                             population_size,
                             population_stddev,
                             seed):
  """Constructs the initial population.

  If an initial population is not already provided, this function constructs
  a population by adding random normal noise to the initial position.

  Args:
    initial_population: None or a list of `Tensor`s. The initial population.
    initial_position: None or a list of `Tensor`s. The initial position.
      If initial_population is None, this argument must not be None.
    population_size: Scalar integer `Tensor`. The number of members in the
      population. If the initial population is not None, this parameter is
      ignored.
    population_stddev: A positive scalar real `Tensor` of the same dtype
      as `initial_position` or `initial_population` (whichever is not None).
      This parameter is ignored if `initial_population`
      is specified. Used to generate the population from the
      `initial_position` by adding random normal noise with zero mean and
      the specified standard deviation.
    seed: Seed for random number generation.

  Returns:
    A list of `Tensor`s. The initial population.
  """
  if initial_population is not None:
    return [tf.convert_to_tensor(value=part) for part in initial_population]
  # Constructs the population by adding normal noise to the initial position.
  seed_stream = distributions.SeedStream(seed, salt='get_starting_population')
  population = []
  for part in initial_position:
    part = tf.convert_to_tensor(value=part)
    part_event_shape = tf.shape(input=part)
    # We only draw population_size-1 random vectors because we want to ensure
    # that the supplied position is part of the population. The first member
    # is set to be the initial_position.
    population_part_shape = tf.concat([[population_size-1],
                                       part_event_shape], axis=0)
    population_part = tf.random.normal(population_part_shape,
                                       stddev=population_stddev,
                                       dtype=part.dtype.base_dtype,
                                       seed=seed_stream())
    population_part += part
    population_part = tf.concat([[part], population_part], axis=0)
    population.append(population_part)
  return population
def _get_starting_population(initial_population,
                             initial_position,
                             population_size,
                             population_stddev,
                             seed):
  """Constructs the initial population.

  If an initial population is not already provided, this function constructs
  a population by adding random normal noise to the initial position.

  Args:
    initial_population: None or a list of `Tensor`s. The initial population.
    initial_position: None or a list of `Tensor`s. The initial position.
      If initial_population is None, this argument must not be None.
    population_size: Scalar integer `Tensor`. The number of members in the
      population. If the initial population is not None, this parameter is
      ignored.
    population_stddev: A positive scalar real `Tensor` of the same dtype
      as `initial_position` or `initial_population` (whichever is not None).
      This parameter is ignored if `initial_population`
      is specified. Used to generate the population from the
      `initial_position` by adding random normal noise with zero mean and
      the specified standard deviation.
    seed: Seed for random number generation.

  Returns:
    A list of `Tensor`s. The initial population.
  """
  if initial_population is not None:
    return [tf.convert_to_tensor(value=part) for part in initial_population]
  # Constructs the population by adding normal noise to the initial position.
  seed_stream = distributions.SeedStream(seed, salt='get_starting_population')
  population = []
  for part in initial_position:
    part = tf.convert_to_tensor(value=part)
    part_event_shape = tf.shape(input=part)
    # We only draw population_size-1 random vectors because we want to ensure
    # that the supplied position is part of the population. The first member
    # is set to be the initial_position.
    population_part_shape = tf.concat([[population_size-1],
                                       part_event_shape], axis=0)
    population_part = tf.random.normal(population_part_shape,
                                       stddev=population_stddev,
                                       dtype=part.dtype.base_dtype,
                                       seed=seed_stream())
    population_part += part
    population_part = tf.concat([[part], population_part], axis=0)
    population.append(population_part)
  return population
Constructs the initial population.

  If an initial population is not already provided, this function constructs
  a population by adding random normal noise to the initial position.

  Args:
    initial_population: None or a list of `Tensor`s. The initial population.
    initial_position: None or a list of `Tensor`s. The initial position.
      If initial_population is None, this argument must not be None.
    population_size: Scalar integer `Tensor`. The number of members in the
      population. If the initial population is not None, this parameter is
      ignored.
    population_stddev: A positive scalar real `Tensor` of the same dtype
      as `initial_position` or `initial_population` (whichever is not None).
      This parameter is ignored if `initial_population`
      is specified. Used to generate the population from the
      `initial_position` by adding random normal noise with zero mean and
      the specified standard deviation.
    seed: Seed for random number generation.

  Returns:
    A list of `Tensor`s. The initial population.