Class Distribution

tensorflow/python/ops/distributions/distribution.py:280–1323

A generic probability distribution base class. `Distribution` is a base class for constructing and organizing properties (e.g., mean, variance) of random variables (e.g, Bernoulli, Gaussian). #### Subclassing Subclasses are expected to implement a leading-underscore version of the same-

@six.add_metaclass(_DistributionMeta)
@tf_export(v1=["distributions.Distribution"])
class Distribution(_BaseDistribution):
  """A generic probability distribution base class.

  `Distribution` is a base class for constructing and organizing properties
  (e.g., mean, variance) of random variables (e.g, Bernoulli, Gaussian).

  #### Subclassing

  Subclasses are expected to implement a leading-underscore version of the
  same-named function. The argument signature should be identical except for
  the omission of `name="..."`. For example, to enable `log_prob(value,
  name="log_prob")` a subclass should implement `_log_prob(value)`.

  Subclasses can append to public-level docstrings by providing
  docstrings for their method specializations. For example:

  ```python
  @util.AppendDocstring("Some other details.")
  def _log_prob(self, value):
    ...
  ```

  would add the string "Some other details." to the `log_prob` function
  docstring. This is implemented as a simple decorator to avoid python
  linter complaining about missing Args/Returns/Raises sections in the
  partial docstrings.

  #### Broadcasting, batching, and shapes

  All distributions support batches of independent distributions of that type.
  The batch shape is determined by broadcasting together the parameters.

  The shape of arguments to `__init__`, `cdf`, `log_cdf`, `prob`, and
  `log_prob` reflect this broadcasting, as does the return value of `sample` and
  `sample_n`.

  `sample_n_shape = [n] + batch_shape + event_shape`, where `sample_n_shape` is
  the shape of the `Tensor` returned from `sample_n`, `n` is the number of
  samples, `batch_shape` defines how many independent distributions there are,
  and `event_shape` defines the shape of samples from each of those independent
  distributions. Samples are independent along the `batch_shape` dimensions, but
  not necessarily so along the `event_shape` dimensions (depending on the
  particulars of the underlying distribution).

  Using the `Uniform` distribution as an example:

  ```python
  minval = 3.0
  maxval = [[4.0, 6.0],
            [10.0, 12.0]]

  # Broadcasting:
  # This instance represents 4 Uniform distributions. Each has a lower bound at
  # 3.0 as the `minval` parameter was broadcasted to match `maxval`'s shape.
  u = Uniform(minval, maxval)

  # `event_shape` is `TensorShape([])`.
  event_shape = u.event_shape