


from __future__ import annotations

import math
from collections import Counter
from string import ascii_lowercase







def SCREAMING_SNAKE_CASE	(			__lowerCAmelCase				)    ->				None:
  snake_case__				,				snake_case__						= analyze_text(__lowerCAmelCase				)
  snake_case__						= list(''' ''' + ascii_lowercase				)
  # what is our total sum of probabilities.
  snake_case__						= sum(single_char_strings.values()				)

  # one length string
  snake_case__						= 0
  # for each alpha we go in our dict and if it is in it we calculate entropy
  for ch in my_alphas:
    if ch in single_char_strings:
      snake_case__						= single_char_strings[ch]
      snake_case__						= my_str / all_sum
      my_fir_sum += prob * math.loga(__lowerCAmelCase				)  # entropy formula.

    # print entropy
  print(F"""{round(-1 * my_fir_sum				):.1f}"""				)

  # two len string
  snake_case__						= sum(two_char_strings.values()				)
  snake_case__						= 0
  # for each alpha (two in size) calculate entropy.
  for cha in my_alphas:
    for cha in my_alphas:
      snake_case__						= cha + cha
      if sequence in two_char_strings:
        snake_case__						= two_char_strings[sequence]
        snake_case__						= int(__lowerCAmelCase				) / all_sum
        my_sec_sum += prob * math.loga(__lowerCAmelCase				)

    # print second entropy
  print(F"""{round(-1 * my_sec_sum				):.1f}"""				)

  # print the difference between them
  print(F"""{round((-1 * my_sec_sum) - (-1 * my_fir_sum)				):.1f}"""				)







def SCREAMING_SNAKE_CASE	(			__lowerCAmelCase				)    ->				tuple[dict, dict]:
  snake_case__						= Counter()  # type: ignore
  snake_case__						= Counter()  # type: ignore
  single_char_strings[text[-1]] += 1

  # first case when we have space at start.
  two_char_strings[" " + text[0]] += 1
  for i in range(0							,   len(__lowerCAmelCase				) - 1				):
    single_char_strings[text[i]] += 1
    two_char_strings[text[i : i + 2]] += 1
  return single_char_strings, two_char_strings







def SCREAMING_SNAKE_CASE	(			)    ->				int:
  import doctest

  doctest.testmod()
  # text = (
  #     "Had repulsive dashwoods suspicion sincerity but advantage now him. Remark "
  #     "easily garret nor nay. Civil those mrs enjoy shy fat merry. You greatest "
  #     "jointure saw horrible. He private he on be imagine suppose. Fertile "
  #     "beloved evident through no service elderly is. Blind there if every no so "
  #     "at. Own neglected you preferred way sincerity delivered his attempted. To "
  #     "of message cottage windows do besides against uncivil.  Delightful "
  #     "unreserved impossible few estimating men favourable see entreaties. She "
  #     "propriety immediate was improving. He or entrance humoured likewise "
  #     "moderate. Much nor game son say feel. Fat make met can must form into "
  #     "gate. Me we offending prevailed discovery. "
  # )

  # calculate_prob(text)


if __name__ == "__main__":
   main()





import numpy as np
import torch
from torch.nn import CrossEntropyLoss
from transformers import AutoModelForCausalLM, AutoTokenizer

import datasets
from datasets import logging


lowerCamelCase__							:						Any							     =   """\

"""

lowerCamelCase__							:						List[str]							     =   """
Perplexity (PPL) is one of the most common metrics for evaluating language models.
It is defined as the exponentiated average negative log-likelihood of a sequence.

For more information, see https://huggingface.co/docs/transformers/perplexity
"""

lowerCamelCase__							:						Any							     =   """
Args:
    model_id (str): model used for calculating Perplexity
            NOTE: Perplexity can only be calculated for causal language models.
                    This includes models such as gpt2, causal variations of bert,
                    causal versions of t5, and more (the full list can be found
                    in the AutoModelForCausalLM documentation here:
                    https://huggingface.co/docs/transformers/master/en/model_doc/auto#transformers.AutoModelForCausalLM )

    input_texts (list of str): input text, each separate text snippet
        is one list entry.
    batch_size (int): the batch size to run texts through the model. Defaults to 16.
    add_start_token (bool): whether to add the start token to the texts,
        so the perplexity can include the probability of the first word. Defaults to True.
    device (str): device to run on, defaults to 'cuda' when available
Returns:
    perplexity: dictionary containing the perplexity scores for the texts
        in the input list, as well as the mean perplexity. If one of the input texts is
        longer than the max input length of the model, then it is truncated to the
        max length for the perplexity computation.
Examples:
    Example 1:
        >>> perplexity = datasets.load_metric(\"perplexity\")
        >>> input_texts = [\"lorem ipsum\", \"Happy Birthday!\", \"Bienvenue\"]
        >>> results = perplexity.compute(model_id='gpt2',
        ...                              add_start_token=False,
        ...                              input_texts=input_texts) # doctest:+ELLIPSIS
        >>> print(list(results.keys()))
        ['perplexities', 'mean_perplexity']
        >>> print(round(results[\"mean_perplexity\"], 2))
        78.22
        >>> print(round(results[\"perplexities\"][0], 2))
        11.11

    Example 2:
        >>> perplexity = datasets.load_metric(\"perplexity\")
        >>> input_texts = datasets.load_dataset(\"wikitext\",
        ...                                     \"wikitext-2-raw-v1\",
        ...                                     split=\"test\")[\"text\"][:50] # doctest:+ELLIPSIS
        [...]
        >>> input_texts = [s for s in input_texts if s!='']
        >>> results = perplexity.compute(model_id='gpt2',
        ...                              input_texts=input_texts) # doctest:+ELLIPSIS
        >>> print(list(results.keys()))
        ['perplexities', 'mean_perplexity']
        >>> print(round(results[\"mean_perplexity\"], 2))
        60.35
        >>> print(round(results[\"perplexities\"][0], 2))
        81.12
"""
@datasets.utils.file_utils.add_start_docstrings(_DESCRIPTION   ,_KWARGS_DESCRIPTION				)
class 		__magic_name__						(datasets.Metric				):





     '''simple docstring'''



     def 	SCREAMING_SNAKE_CASE__						(					self:int   ):
       return datasets.MetricInfo(
           description=_DESCRIPTION     ,		citation=_CITATION     ,		inputs_description=_KWARGS_DESCRIPTION     ,		features=datasets.Features(
               {
                   '''input_texts''': datasets.Value('''string'''   ),
               }   )     ,		reference_urls=['''https://huggingface.co/docs/transformers/perplexity''']     ,		)







     def 	SCREAMING_SNAKE_CASE__						(					self:List[Any]     ,		_a:int     ,		_a:List[Any]     ,		_a:int = 16     ,		_a:bool = True     ,		_a:Any=None   ):
       if device is not None:
         assert device in ["gpu", "cpu", "cuda"], "device should be either gpu or cpu."
         if device == "gpu":
           snake_case__						= '''cuda'''
       else:
         snake_case__						= '''cuda''' if torch.cuda.is_available() else '''cpu'''

       snake_case__						= AutoModelForCausalLM.from_pretrained(_a   )
       snake_case__						= model.to(_a   )

       snake_case__						= AutoTokenizer.from_pretrained(_a   )

       # if batch_size > 1 (which generally leads to padding being required), and
       # if there is not an already assigned pad_token, assign an existing
       # special token to also be the padding token
       if tokenizer.pad_token is None and batch_size > 1:
         snake_case__						= list(tokenizer.special_tokens_map_extended.values()   )
         # check that the model already has at least one special token defined
         assert (
             len(_a   ) > 0
         ), "If batch_size > 1, model must have at least one special token to use for padding. Please use a different model or set batch_size=1."
         # assign one of the special tokens to also be the pad token
         tokenizer.add_special_tokens({'''pad_token''': existing_special_tokens[0]}   )

       if add_start_token:
         # leave room for <BOS> token to be added:
         assert (
             tokenizer.bos_token is not None
         ), "Input model must already have a BOS token if using add_start_token=True. Please use a different model, or set add_start_token=False"
         snake_case__						= model.config.max_length - 1
       else:
         snake_case__						= model.config.max_length

       snake_case__						= tokenizer(
           _a     ,		add_special_tokens=_a     ,		padding=_a     ,		truncation=_a     ,		max_length=_a     ,		return_tensors='''pt'''     ,		return_attention_mask=_a     ,		).to(_a   )

       snake_case__						= encodings['''input_ids''']
       snake_case__						= encodings['''attention_mask''']

       # check that each input is long enough:
       if add_start_token:
         assert torch.all(torch.ge(attn_masks.sum(1   )     ,		1   )   ), "Each input text must be at least one token long."
       else:
         assert torch.all(
             torch.ge(attn_masks.sum(1   )     ,		2   )   ), "When add_start_token=False, each input text must be at least two tokens long. Run with add_start_token=True if inputting strings of only one token, and remove all empty input strings."

       snake_case__						= []
       snake_case__						= CrossEntropyLoss(reduction='''none'''   )

       for start_index in logging.tqdm(range(0     ,		len(_a   )     ,		_a   )   ):
         snake_case__						= min(start_index + batch_size     ,		len(_a   )   )
         snake_case__						= encoded_texts[start_index:end_index]
         snake_case__						= attn_masks[start_index:end_index]

         if add_start_token:
           snake_case__						= torch.tensor([[tokenizer.bos_token_id]] * encoded_batch.size(dim=0   )   ).to(_a   )
           snake_case__						= torch.cat([bos_tokens_tensor, encoded_batch]     ,		dim=1   )
           snake_case__						= torch.cat(
               [torch.ones(bos_tokens_tensor.size()     ,		dtype=torch.intaa   ).to(_a   ), attn_mask]     ,		dim=1   )

         snake_case__						= encoded_batch

         with torch.no_grad():
           snake_case__						= model(_a     ,		attention_mask=_a   ).logits

         snake_case__						= out_logits[..., :-1, :].contiguous()
         snake_case__						= labels[..., 1:].contiguous()
         snake_case__						= attn_mask[..., 1:].contiguous()

         snake_case__						= torch.expa(
             (loss_fct(shift_logits.transpose(1     ,		2   )     ,		_a   ) * shift_attention_mask_batch).sum(1   )
             / shift_attention_mask_batch.sum(1   )   )

         ppls += perplexity_batch.tolist()

       return {"perplexities": ppls, "mean_perplexity": np.mean(_a   )}

