U d@shddlZddlmZddlmZddlmZddlmZm Z ddl m Z ddl m Z Gdd d eZdS) N) constraints) Distribution) Independent)ComposeTransform Transform)_sum_rightmost)DictcseZdZUdZiZeeejfe d<dfdd Z dfdd Z ej dd d d Z ed d ZefddZefddZddZddZddZddZZS)TransformedDistributiona Extension of the Distribution class, which applies a sequence of Transforms to a base distribution. Let f be the composition of transforms applied:: X ~ BaseDistribution Y = f(X) ~ TransformedDistribution(BaseDistribution, f) log p(Y) = log p(X) + log |det (dX/dY)| Note that the ``.event_shape`` of a :class:`TransformedDistribution` is the maximum shape of its base distribution and its transforms, since transforms can introduce correlations among events. An example for the usage of :class:`TransformedDistribution` would be:: # Building a Logistic Distribution # X ~ Uniform(0, 1) # f = a + b * logit(X) # Y ~ f(X) ~ Logistic(a, b) base_distribution = Uniform(0, 1) transforms = [SigmoidTransform().inv, AffineTransform(loc=a, scale=b)] logistic = TransformedDistribution(base_distribution, transforms) For more examples, please look at the implementations of :class:`~torch.distributions.gumbel.Gumbel`, :class:`~torch.distributions.half_cauchy.HalfCauchy`, :class:`~torch.distributions.half_normal.HalfNormal`, :class:`~torch.distributions.log_normal.LogNormal`, :class:`~torch.distributions.pareto.Pareto`, :class:`~torch.distributions.weibull.Weibull`, :class:`~torch.distributions.relaxed_bernoulli.RelaxedBernoulli` and :class:`~torch.distributions.relaxed_categorical.RelaxedOneHotCategorical` arg_constraintsNcsRt|tr|g|_n:t|tr@tdd|Ds8td||_ntd||j|j}t |j}t |j}|j j }t ||krtd||| |}||} || kr| dt | |} || }||} | dkrt|| }||_|jj t||d} t || kstt || } |d| }|| d}tt|j|||ddS)Ncss|]}t|tVqdSN) isinstancer).0trP/tmp/pip-unpacked-wheel-ua33x9lu/torch/distributions/transformed_distribution.py 1sz3TransformedDistribution.__init__..z6transforms must be a Transform or a list of Transformsz2transforms must be a Transform or list, but was {}zHbase_distribution needs to have shape with size at least {}, but got {}.r validate_args)r r transformslistall ValueErrorformat batch_shape event_shapelenrdomain event_dimZ forward_shape inverse_shapeexpandr base_distcodomainmaxAssertionErrorsuperr __init__)selfZbase_distributionrrZ base_shapeZbase_event_dim transformZdomain_event_dimshapeZexpanded_base_shapebase_batch_shapeZreinterpreted_batch_ndimsrZcutrr __class__rrr%-s>              z TransformedDistribution.__init__cs|t|}t|}||j}t|jD]}||}q*|dt|t|j j}|j ||_ |j|_t t|j ||jdd|j |_ |S)NFr)Z_get_checked_instancer torchSizerreversedrrrr rr$r%_validate_args)r&rZ _instancenewr(rr)r*rrrQs    zTransformedDistribution.expandF)Z is_discretecCsF|js|jjS|jdj}t|j|jkrBt|t|j|j}|S)N) rr supportr!rrrrZ independent)r&r2rrrr2^s  zTransformedDistribution.supportcCs|jjSr )r has_rsample)r&rrrr3gsz#TransformedDistribution.has_rsamplec CsDt2|j|}|jD] }||}q|W5QRSQRXdS)a Generates a sample_shape shaped sample or sample_shape shaped batch of samples if the distribution parameters are batched. Samples first from base distribution and applies `transform()` for every transform in the list. N)r,Zno_gradr samplerr&Z sample_shapexr'rrrr4ks     zTransformedDistribution.samplecCs$|j|}|jD] }||}q|S)a$ Generates a sample_shape shaped reparameterized sample or sample_shape shaped batch of reparameterized samples if the distribution parameters are batched. Samples first from base distribution and applies `transform()` for every transform in the list. )r rsamplerr5rrrr7xs   zTransformedDistribution.rsamplecCs|jr||t|j}d}|}t|jD]D}||}||jj|j j7}|t | ||||jj}|}q,|t |j ||t|j j}|S)z Scores the sample by inverting the transform(s) and computing the score using the score of the base distribution and the log abs det jacobian. g)r/_validate_samplerrr.rinvrrr!rZlog_abs_det_jacobianr log_prob)r&valuerr:yr'r6rrrr:s     z TransformedDistribution.log_probcCs@d}|jD]}||j}q t|tr0|dkr0|S||ddS)zu This conditionally flips ``value -> 1-value`` to ensure :meth:`cdf` is monotone increasing. g?)rsignr int)r&r;r>r'rrr_monotonize_cdfs   z'TransformedDistribution._monotonize_cdfcCsL|jdddD]}||}q|jr2|j||j|}||}|S)z Computes the cumulative distribution function by inverting the transform(s) and computing the score of the base distribution. Nr1)rr9r/r r8cdfr@r&r;r'rrrrAs    zTransformedDistribution.cdfcCs.||}|j|}|jD] }||}q|S)z Computes the inverse cumulative distribution function using transform(s) and computing the score of the base distribution. )r@r icdfrrBrrrrCs     zTransformedDistribution.icdf)N)N)__name__ __module__ __qualname____doc__r rstrrZ Constraint__annotations__r%rZdependent_propertyr2propertyr3r,r-r4r7r:r@rArC __classcell__rrr*rr s  $       r )r,Ztorch.distributionsrZ torch.distributions.distributionrZtorch.distributions.independentrZtorch.distributions.transformsrrZtorch.distributions.utilsrtypingrr rrrrs