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ColossalAI/colossalai/inference/logit_processors.py

92 lines
2.6 KiB

import torch
import torch.nn.functional as F
_LOGIT_PROCESSOR_MAP = {}
def register_logit_processor(process_type):
"""
register flops computation function for operation.
"""
def register(func):
global _LOGIT_PROCESSOR_MAP
_LOGIT_PROCESSOR_MAP[process_type] = func
return func
return register
@register_logit_processor("temperature")
def temperature_logit_process(logits, temperature: float):
"""
apply temperature scaling.
"""
if not isinstance(temperature, float) or not (0.0 < temperature <= 1.0):
except_msg = f"'temperature={temperature}' should be a strictly positive float, less than or equal to 1.0 and greater than 0."
if temperature == 0.0:
except_msg += "if you want to use greedy decoding strategies, set `do_sample=False`."
raise ValueError(except_msg)
return logits if temperature == 1.0 else logits / temperature
@register_logit_processor("top_k")
def top_k_logit_processor(logits, top_k: int):
"""
top_k logit processor
"""
if not isinstance(top_k, int) or top_k <= 0:
raise ValueError(f"`top_k` should be a strictly positive integer, but got {top_k}.")
indices_to_remove = logits < torch.topk(logits, top_k)[0][..., -1, None]
logits[indices_to_remove] = -float("inf")
return logits
@register_logit_processor("top_p")
def top_p_logit_processor(logits, top_p: float):
"""
top_p logit processor
"""
if top_p < 0 or top_p > 1.0:
raise ValueError(f"`top_p` should be a float > 0 and < 1, but got {top_p}.")
sorted_logits, sorted_indices = torch.sort(logits, descending=True)
cumulative_probs = torch.cumsum(F.softmax(sorted_logits, dim=-1), dim=-1)
sorted_indices_to_remove = cumulative_probs > top_p
sorted_indices_to_remove = torch.roll(sorted_indices_to_remove, 1, -1)
sorted_indices_to_remove[..., 0] = 0
indices_to_remove = sorted_indices_to_remove.scatter(dim=1, index=sorted_indices, src=sorted_indices_to_remove)
logits[indices_to_remove] = -float("inf")
return logits
def logit_processor(processor: str, logits, attrs):
"""
do logit process for given logits.
Args:
processor(str): the type of logit processor
logits(torch.Tensor): input logits
attrs(dict): attrs of the logit processor
Returns:
logits after process
"""
if processor not in _LOGIT_PROCESSOR_MAP:
return logits
else:
func = _LOGIT_PROCESSOR_MAP[processor]
try:
logits = func(logits, attrs)
except Exception:
return logits
return logits