gluonts.mx.distribution.dirichlet_multinomial module#
- class gluonts.mx.distribution.dirichlet_multinomial.DirichletMultinomial(dim: int, n_trials: int, alpha: typing.Union[mxnet.ndarray.ndarray.NDArray, mxnet.symbol.symbol.Symbol], float_type: typing.Type = <class 'numpy.float32'>)[source]#
Bases:
gluonts.mx.distribution.distribution.Distribution
Dirichlet-Multinomial distribution, specified by the concentration vector alpha of length dim, and a number of trials n_trials. https://en.wikipedia.org/wiki/Dirichlet-multinomial_distribution.
The Dirichlet-Multinomial distribution is a discrete multivariate probability distribution, a sample (or observation) x = (x_0,…, x_{dim-1}) must satisfy:
sum_k x_k = n_trials and for all k, x_k is a non-negative integer.
Such a sample can be obtained by first drawing a vector p from a Dirichlet(alpha) distribution, then x is drawn from a Multinomial(p) with n trials.
- Parameters
dim – Dimension of any sample
n_trials – Number of trials
alpha – concentration vector, of shape (…, dim)
F – A module that can either refer to the Symbol API or the NDArray API in MXNet
- property F#
- arg_names: Tuple#
- property batch_shape: Tuple#
Layout of the set of events contemplated by the distribution.
Invoking sample() from a distribution yields a tensor of shape batch_shape + event_shape, and computing log_prob (or loss more in general) on such sample will yield a tensor of shape batch_shape.
This property is available in general only in mx.ndarray mode, when the shape of the distribution arguments can be accessed.
- property event_dim: int#
Number of event dimensions, i.e., length of the event_shape tuple.
This is 0 for distributions over scalars, 1 over vectors, 2 over matrices, and so on.
- property event_shape: Tuple#
Shape of each individual event contemplated by the distribution.
For example, distributions over scalars have event_shape = (), over vectors have event_shape = (d, ) where d is the length of the vectors, over matrices have event_shape = (d1, d2), and so on.
Invoking sample() from a distribution yields a tensor of shape batch_shape + event_shape.
This property is available in general only in mx.ndarray mode, when the shape of the distribution arguments can be accessed.
- is_reparameterizable = False#
- log_prob(x: Union[mxnet.ndarray.ndarray.NDArray, mxnet.symbol.symbol.Symbol]) Union[mxnet.ndarray.ndarray.NDArray, mxnet.symbol.symbol.Symbol] [source]#
Compute the log-density of the distribution at x.
- Parameters
x – Tensor of shape (*batch_shape, *event_shape).
- Returns
Tensor of shape batch_shape containing the log-density of the distribution for each event in x.
- Return type
Tensor
- property mean: Union[mxnet.ndarray.ndarray.NDArray, mxnet.symbol.symbol.Symbol]#
Tensor containing the mean of the distribution.
- sample(num_samples: typing.Optional[int] = None, dtype=<class 'numpy.float32'>) Union[mxnet.ndarray.ndarray.NDArray, mxnet.symbol.symbol.Symbol] [source]#
Draw samples from the distribution.
If num_samples is given the first dimension of the output will be num_samples.
- Parameters
num_samples – Number of samples to to be drawn.
dtype – Data-type of the samples.
- Returns
A tensor containing samples. This has shape (*batch_shape, *eval_shape) if num_samples = None and (num_samples, *batch_shape, *eval_shape) otherwise.
- Return type
Tensor
- property variance: Union[mxnet.ndarray.ndarray.NDArray, mxnet.symbol.symbol.Symbol]#
Tensor containing the variance of the distribution.
- class gluonts.mx.distribution.dirichlet_multinomial.DirichletMultinomialOutput(dim: int, n_trials: int)[source]#
Bases:
gluonts.mx.distribution.distribution_output.DistributionOutput
- args_dim: Dict[str, int]#
- distr_cls: type#
- distribution(distr_args, loc=None, scale=None) gluonts.mx.distribution.distribution.Distribution [source]#
Construct the associated distribution, given the collection of constructor arguments and, optionally, a scale tensor.
- Parameters
distr_args – Constructor arguments for the underlying Distribution type.
loc – Optional tensor, of the same shape as the batch_shape+event_shape of the resulting distribution.
scale – Optional tensor, of the same shape as the batch_shape+event_shape of the resulting distribution.
- domain_map(F, alpha_vector)[source]#
Converts arguments to the right shape and domain.
The domain depends on the type of distribution, while the correct shape is obtained by reshaping the trailing axis in such a way that the returned tensors define a distribution of the right event_shape.
- property event_shape: Tuple#
Shape of each individual event contemplated by the distributions that this object constructs.