flax.linen.while_loop#
- flax.linen.while_loop(cond_fn, body_fn, mdl, init, carry_variables=False, broadcast_variables=True, split_rngs=FrozenDict({}))[source]#
Lifted version of jax.lax.while_loop.
The lifted scope is passed to cond_fn and body_fn. Broadcasted variables are immutable. The carry variable are mutable but cannot change shape and dtype. This also means you cannot initialize variables inside the body. Consider calling body_fn once manually before calling while_loop if variable initialization is required.
Example:
>>> import flax.linen as nn >>> import jax, jax.numpy as jnp >>> class WhileLoopExample(nn.Module): ... @nn.compact ... def __call__(self, x): ... def cond_fn(mdl, c): ... return mdl.variables['state']['acc'] < 10 ... def body_fn(mdl, c): ... acc = mdl.variable('state', 'acc', lambda: jnp.array(0)) ... acc.value += 1 ... y = nn.Dense(c.shape[-1])(c) ... return y ... c = x ... if self.is_mutable_collection('params'): ... return body_fn(self, c) ... else: ... return nn.while_loop(cond_fn, body_fn, self, c, ... carry_variables='state') >>> k = jax.random.key(0) >>> x = jnp.ones((2, 2)) >>> intial_vars = WhileLoopExample().init(k, x) >>> result, state = WhileLoopExample().apply(intial_vars, x, mutable=['state'])
- Parameters
cond_fn – Should return True as long as the loop should continue.
body_fn – The body of the while loop.
mdl – The Module which should be lifted into the loop.
init – The initial state passed to the loop
carry_variables – collections that are carried through the loop and are therefore mutable (default: none).
broadcast_variables – collections that are closed over and are therefore read-only (default: all collections)
split_rngs – Split PRNG sequences will be different for each loop iterations. If split is False the PRNGs will be the same across iterations.
- Returns
The final state after executing the while loop.