eval.py

#!/usr/bin/env python3
import argparse
import re
from typing import Dict

import torch
from datasets import Audio, Dataset, load_dataset, load_metric

from transformers import AutoFeatureExtractor, pipeline

import re
from num2words import num2words


def log_results(result: Dataset, args: Dict[str, str]):
    """DO NOT CHANGE. This function computes and logs the result metrics."""

    log_outputs = args.log_outputs
    dataset_id = "_".join(args.dataset.split("/") + [args.config, args.split])

    # load metric
    wer = load_metric("wer")
    cer = load_metric("cer")

    # compute metrics
    wer_result = wer.compute(references=result["target"], predictions=result["prediction"])
    cer_result = cer.compute(references=result["target"], predictions=result["prediction"])

    # print & log results
    result_str = f"WER: {wer_result}\n" f"CER: {cer_result}"
    print(result_str)

    with open(f"{dataset_id}_eval_results.txt", "w") as f:
        f.write(result_str)

    # log all results in text file. Possibly interesting for analysis
    if log_outputs is not None:
        pred_file = f"log_{dataset_id}_predictions.txt"
        target_file = f"log_{dataset_id}_targets.txt"

        with open(pred_file, "w") as p, open(target_file, "w") as t:

            # mapping function to write output
            def write_to_file(batch, i):
                p.write(f"{i}" + "\n")
                p.write(batch["prediction"] + "\n")
                t.write(f"{i}" + "\n")
                t.write(batch["target"] + "\n")

            result.map(write_to_file, with_indices=True)


def spell_num(text):
    l = []
    for t in text.split():
        if t.isdigit():
            l.append(num2words(t, lang='de'))
        else:
            l.append(t)
    
    return ' '.join(l)

ALLOWED_CHARS = {
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
    'ä', 'ö', 'ü',
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
    ' ',
    ',', ';', ':', '.', '?', '!',
}
WHITESPACE_REGEX = re.compile(r'[ \t]+')


def preprocess_transcript_for_corpus(transcript):
    transcript = transcript.lower()
    transcript = transcript.replace('á', 'a')
    transcript = transcript.replace('à', 'a')
    transcript = transcript.replace('â', 'a')
    transcript = transcript.replace('ç', 'c')
    transcript = transcript.replace('é', 'e')
    transcript = transcript.replace('è', 'e')
    transcript = transcript.replace('ê', 'e')
    transcript = transcript.replace('í', 'i')
    transcript = transcript.replace('ì', 'i')
    transcript = transcript.replace('î', 'i')
    transcript = transcript.replace('ñ', 'n')
    transcript = transcript.replace('ó', 'o')
    transcript = transcript.replace('ò', 'o')
    transcript = transcript.replace('ô', 'o')
    transcript = transcript.replace('ú', 'u')
    transcript = transcript.replace('ù', 'u')
    transcript = transcript.replace('û', 'u')
    transcript = transcript.replace('ș', 's')
    transcript = transcript.replace('ş', 's')
    transcript = transcript.replace('ß', 'ss')
    transcript = transcript.replace('-', ' ')
    # Not used consistently, better to replace with space as well
    transcript = transcript.replace('–', ' ')
    transcript = transcript.replace('/', ' ')
    transcript = WHITESPACE_REGEX.sub(' ', transcript)
    transcript = ''.join([char for char in transcript if char in ALLOWED_CHARS])
    transcript = WHITESPACE_REGEX.sub(' ', transcript)
    transcript = spell_num(transcript)
    transcript = transcript.replace('ß', 'ss')
    transcript = transcript.strip()

    return transcript

def normalize_text(text: str) -> str:
    """DO ADAPT FOR YOUR USE CASE. this function normalizes the target text."""

    text = preprocess_transcript_for_corpus(txt)
    chars_to_ignore_regex = '[,?.!\-\;\:"“%‘”�—’…–]'  
    text = re.sub(chars_to_ignore_regex, "", text.lower())

    # In addition, we can normalize the target text, e.g. removing new lines characters etc...
    # note that order is important here!
    #token_sequences_to_ignore = ["\n\n", "\n", "   ", "  "]

    #for t in token_sequences_to_ignore:
    #    text = " ".join(text.split(t))

    return text.strip()


def main(args):
    # load dataset
    dataset = load_dataset(args.dataset, args.config, split=args.split, use_auth_token=True)

    # for testing: only process the first two examples as a test
    # dataset = dataset.select(range(10))

    # load processor
    feature_extractor = AutoFeatureExtractor.from_pretrained(args.model_id)
    sampling_rate = feature_extractor.sampling_rate

    # resample audio
    dataset = dataset.cast_column("audio", Audio(sampling_rate=sampling_rate))

    # load eval pipeline
    if args.device is None:
        args.device = 0 if torch.cuda.is_available() else -1
    asr = pipeline("automatic-speech-recognition", model=args.model_id, device=args.device)

    # map function to decode audio
    def map_to_pred(batch):
        prediction = asr(
            batch["audio"]["array"], chunk_length_s=args.chunk_length_s, stride_length_s=args.stride_length_s
        )

        batch["prediction"] = prediction["text"]
        batch["target"] = normalize_text(batch["sentence"])
        return batch

    # run inference on all examples
    result = dataset.map(map_to_pred, remove_columns=dataset.column_names)

    # compute and log_results
    # do not change function below
    log_results(result, args)


if __name__ == "__main__":
    parser = argparse.ArgumentParser()

    parser.add_argument(
        "--model_id", type=str, required=True, help="Model identifier. Should be loadable with 🤗 Transformers"
    )
    parser.add_argument(
        "--dataset",
        type=str,
        required=True,
        help="Dataset name to evaluate the `model_id`. Should be loadable with 🤗 Datasets",
    )
    parser.add_argument(
        "--config", type=str, required=True, help="Config of the dataset. *E.g.* `'en'`  for Common Voice"
    )
    parser.add_argument("--split", type=str, required=True, help="Split of the dataset. *E.g.* `'test'`")
    parser.add_argument(
        "--chunk_length_s", type=float, default=None, help="Chunk length in seconds. Defaults to 5 seconds."
    )
    parser.add_argument(
        "--stride_length_s", type=float, default=None, help="Stride of the audio chunks. Defaults to 1 second."
    )
    parser.add_argument(
        "--log_outputs", action="store_true", help="If defined, write outputs to log file for analysis."
    )
    parser.add_argument(
        "--device",
        type=int,
        default=None,
        help="The device to run the pipeline on. -1 for CPU (default), 0 for the first GPU and so on.",
    )
    args = parser.parse_args()

    main(args)