Add Pixel CNN++ distribution.

This is a Keras implementation of Pixel CNN++ by Salimans et al. (2017) (https://pdfs.semanticscholar.org/9e90/6792f67cbdda7b7777b69284a81044857656.pdf).

PiperOrigin-RevId: 284616801

Author: emilyfertig

LICENSE

@@ -201,3 +201,219 @@ Copyright 2018 The TensorFlow Probability Authors.  All rights reserved.
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+

tensorflow_probability/python/distributions/BUILD

@@ -93,6 +93,7 @@ py_library(
         ":onehot_categorical",
         ":pareto",
         ":pert",
+        ":pixel_cnn",
         ":plackett_luce",
         ":poisson",
         ":poisson_lognormal",
@@ -1043,6 +1044,27 @@ py_library(
     ],
 )
 
+py_library(
+    name = "pixel_cnn",
+    srcs = ["pixel_cnn.py"],
+    deps = [
+        ":categorical",
+        ":distribution",
+        ":independent",
+        ":logistic",
+        ":mixture_same_family",
+        ":quantized_distribution",
+        ":transformed_distribution",
+        # numpy dep,
+        # tensorflow dep,
+        "//tensorflow_probability/python/bijectors:shift",
+        "//tensorflow_probability/python/internal:prefer_static",
+        "//tensorflow_probability/python/internal:reparameterization",
+        "//tensorflow_probability/python/internal:tensorshape_util",
+        "//tensorflow_probability/python/layers:weight_norm",
+    ],
+)
+
 py_library(
     name = "plackett_luce",
     srcs = ["plackett_luce.py"],
@@ -2277,6 +2299,19 @@ py_test(
     ],
 )
 
+py_test(
+    name = "pixel_cnn_test",
+    size = "large",
+    srcs = ["pixel_cnn_test.py"],
+    shard_count = 8,
+    deps = [
+        # numpy dep,
+        # tensorflow dep,
+        "//tensorflow_probability",
+        "//tensorflow_probability/python/internal:test_util",
+    ],
+)
+
 py_test(
     name = "poisson_test",
     size = "small",

tensorflow_probability/python/distributions/__init__.py

@@ -79,6 +79,7 @@
 from tensorflow_probability.python.distributions.onehot_categorical import OneHotCategorical
 from tensorflow_probability.python.distributions.pareto import Pareto
 from tensorflow_probability.python.distributions.pert import PERT
+from tensorflow_probability.python.distributions.pixel_cnn import PixelCNN
 from tensorflow_probability.python.distributions.plackett_luce import PlackettLuce
 from tensorflow_probability.python.distributions.poisson import Poisson
 from tensorflow_probability.python.distributions.poisson_lognormal import PoissonLogNormalQuadratureCompound
@@ -184,6 +185,7 @@
     'LogitNormal',
     'NegativeBinomial',
     'Normal',
+    'PixelCNN',
     'Poisson',
     'PoissonLogNormalQuadratureCompound',
     'ProbitBernoulli',