pass to CSGLD kernel directly (#459)

blackjax-devs · Apr 13, 2023 · 53c83d1 · 53c83d1
1 parent 7100bca
commit 53c83d1
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Showing 3 changed files with 20 additions and 8 deletions.
diff --git a/blackjax/kernels.py b/blackjax/kernels.py
@@ -668,9 +668,12 @@ class csgld:
 
     Parameters
     ----------
-    logdensity_estimator_fn
+    logdensity_estimator
         A function that returns an estimation of the model's logdensity given
         a position and a batch of data.
+    gradient_estimator
+        A function that takes a position, a batch of data and returns an estimation
+        of the gradient of the log-density at this position.
     zeta
         Hyperparameter that controls the geometric property of the flattened
         density. If `zeta=0` the function reduces to the SGLD step function.
@@ -700,7 +703,8 @@ class csgld:
 
     def __new__(  # type: ignore[misc]
         cls,
-        logdensity_estimator_fn: Callable,
+        logdensity_estimator: Callable,
+        gradient_estimator: Callable,
         zeta: float = 1,
         temperature: float = 0.01,
         num_partitions: int = 512,
@@ -722,7 +726,8 @@ def step_fn(
             return step(
                 rng_key,
                 state,
-                logdensity_estimator_fn,
+                logdensity_estimator,
+                gradient_estimator,
                 minibatch,
                 step_size_diff,
                 step_size_stoch,

diff --git a/blackjax/sgmcmc/csgld.py b/blackjax/sgmcmc/csgld.py
@@ -64,7 +64,8 @@ def kernel(num_partitions=512, energy_gap=10, min_energy=0) -> Callable:
     def one_step(
         rng_key: PRNGKey,
         state: ContourSGLDState,
-        logdensity_estimator_fn: Callable,
+        logdensity_estimator: Callable,
+        gradient_estimator: Callable,
         minibatch: PyTree,
         step_size_diff: float,  # step size for Langevin diffusion
         step_size_stoch: float = 1e-3,  # step size for stochastic approximation
@@ -95,9 +96,12 @@ def one_step(
             State of the pseudo-random number generator.
         state
             Current state of the CSGLD sampler
-        logdensity_estimator_fn
+        logdensity_estimator
             Function that returns an estimation of the value of the density
             function at the current position.
+        gradient_estimator
+            A function that takes a position, a batch of data and returns an estimation
+            of the gradient of the log-density at this position.
         minibatch
             Minibatch of data.
         step_size_diff
@@ -123,7 +127,7 @@ def one_step(
             / energy_gap
         )
 
-        logprob_grad = jax.grad(logdensity_estimator_fn)(position, minibatch)
+        logprob_grad = gradient_estimator(position, minibatch)
         position = integrator(
             rng_key,
             position,
@@ -133,7 +137,7 @@ def one_step(
         )
 
         # Update the stochastic approximation to the energy histogram
-        neg_logprob = -logdensity_estimator_fn(position, minibatch)
+        neg_logprob = -logdensity_estimator(position, minibatch)
         idx = jax.lax.min(
             jax.lax.max(
                 jax.lax.floor((neg_logprob - min_energy) / energy_gap + 1).astype(

diff --git a/tests/mcmc/test_sampling.py b/tests/mcmc/test_sampling.py
@@ -249,7 +249,10 @@ def test_linear_regression_contour_sgld(self):
         logdensity_fn = blackjax.sgmcmc.logdensity_estimator(
             self.logprior_fn, self.loglikelihood_fn, data_size
         )
-        csgld = blackjax.csgld(logdensity_fn)
+        grad_fn = blackjax.sgmcmc.grad_estimator(
+            self.logprior_fn, self.loglikelihood_fn, data_size
+        )
+        csgld = blackjax.csgld(logdensity_fn, grad_fn)
 
         _, rng_key = jax.random.split(rng_key)
         data_batch = X_data[:100, :]