采样器基类
Sampler class
keras_nlp.samplers.Sampler(temperature=1.0)
Base sampler class.
Arguments
- temperature: float. optional. Used to control the
randomness of the sampling. The higher the temperature, the
more diverse the samples. Defaults to
1.0.
Call arguments
{{call_args}}
This base class can be extended to implement different auto-regressive
sampling methods. To do so, override the get_next_token() method, which
computes the next token based on a probability distribution over all
possible vocab entries.
Example
causal_lm = keras_nlp.models.GPT2CausalLM.from_preset("gpt2_base_en")
# Greedy search with some tokens forbidden.
class CustomSampler(keras_nlp.samplers.Sampler):
def __init__(self, forbidden_tokens, **kwargs):
super().__init__(**kwargs)
self.forbidden_tokens = forbidden_tokens
def get_next_token(self, probs):
batch_size, vocab_size = keras.ops.shape(probs)
for id in self.forbidden_tokens:
update = keras.ops.zeros((batch_size, 1))
probs = keras.ops.slice_update(probs, (0, id), update)
return keras.ops.argmax(probs, axis=-1)
# 257 = "a" with a leading space, 262 = "the" with a leading space.
causal_lm.compile(sampler=CustomSampler(forbidden_tokens=[257, 262]))
causal_lm.summary()
causal_lm.generate(["That's strange"])
get_next_token method
Sampler.get_next_token(probabilities)
Get the next token. Arguments
- probabilities: a Tensor, the probability distribution for next token over all vocab tokens.
Get the next token based on given probability distribution over tokens. Subclasses must implement this method.