rapidocr/python/rapidocr/ch_ppocr_rec/utils.py

# -*- encoding: utf-8 -*-
# @Author: SWHL
# @Contact: liekkaskono@163.com
from pathlib import Path
from typing import Any, List, Optional, Tuple, Union

import numpy as np

from ..utils.utils import has_chinese_char
from .typings import WordInfo, WordType


class CTCLabelDecode:
    def __init__(
        self,
        character: Optional[List[str]] = None,
        character_path: Union[str, Path, None] = None,
    ):
        self.character = self.get_character(character, character_path)
        self.dict = {char: i for i, char in enumerate(self.character)}

    def __call__(
        self, preds: np.ndarray, return_word_box: bool = False, **kwargs
    ) -> Tuple[List[Tuple[str, float]], List[Any]]:
        preds_idx = preds.argmax(axis=2)
        preds_prob = preds.max(axis=2)

        wh_ratio_list = kwargs.get("wh_ratio_list", (1.0,))
        max_wh_ratio = kwargs.get("max_wh_ratio", 1.0)

        line_results, word_results = self.decode(
            preds_idx,
            preds_prob,
            return_word_box,
            wh_ratio_list,
            max_wh_ratio,
            remove_duplicate=True,
        )
        return line_results, word_results

    def get_character(
        self,
        character: Optional[List[str]] = None,
        character_path: Union[str, Path, None] = None,
    ) -> List[str]:
        if character is None and character_path is None:
            raise ValueError("character must not be None")

        character_list = None
        if character:
            character_list = character

        if character is None and character_path is not None:
            character_list = self.read_character_file(character_path)

        if character_list is None:
            raise ValueError("character must not be None")

        character_list = self.insert_special_char(
            character_list, " ", len(character_list)
        )
        character_list = self.insert_special_char(character_list, "blank", 0)
        return character_list

    @staticmethod
    def read_character_file(character_path: Union[str, Path]) -> List[str]:
        character_list = []
        with open(character_path, "rb") as f:
            lines = f.readlines()
            for line in lines:
                line = line.decode("utf-8").strip("\n").strip("\r\n")
                character_list.append(line)
        return character_list

    @staticmethod
    def insert_special_char(
        character_list: List[str], special_char: str, loc: int = -1
    ) -> List[str]:
        character_list.insert(loc, special_char)
        return character_list

    def decode(
        self,
        text_index: np.ndarray,
        text_prob: Optional[np.ndarray] = None,
        return_word_box: bool = False,
        wh_ratio_list: Tuple[float] = (1.0,),
        max_wh_ratio: float = 1.0,
        remove_duplicate: bool = False,
    ) -> Tuple[List[Tuple[str, float]], List[WordInfo]]:
        result_list, result_words_list = [], []
        ignored_tokens = self.get_ignored_tokens()
        batch_size = len(text_index)
        for batch_idx in range(batch_size):
            token_indices = text_index[batch_idx]

            selection = np.ones(len(token_indices), dtype=bool)
            if remove_duplicate:
                selection[1:] = token_indices[1:] != token_indices[:-1]

            for ignored_token in ignored_tokens:
                selection &= token_indices != ignored_token

            if text_prob is not None:
                conf_list = np.array(text_prob[batch_idx][selection]).tolist()
                conf_list = [round(conf, 5) for conf in conf_list]
            else:
                conf_list = [1] * len(selection)

            if len(conf_list) == 0:
                conf_list = [0]

            char_list = [
                self.character[text_id] for text_id in token_indices[selection]
            ]
            text = "".join(char_list)

            result_list.append((text, np.mean(conf_list).round(5).tolist()))

            if return_word_box:
                rec_word_info = self.get_word_info(text, selection)
                rec_word_info.line_txt_len = (
                    len(token_indices) * wh_ratio_list[batch_idx] / max_wh_ratio
                )
                rec_word_info.confs = conf_list

                # words holds every character of text except spaces, in order.
                char_confs = iter(
                    conf for char, conf in zip(text, conf_list) if not char.isspace()
                )
                rec_word_info.char_confs = [
                    [next(char_confs) for _ in word] for word in rec_word_info.words
                ]
                result_words_list.append(rec_word_info)
        return result_list, result_words_list

    @staticmethod
    def get_word_info(text: str, selection: np.ndarray) -> WordInfo:
        """
        Group the decoded characters and record the corresponding decoded positions.
        from https://github.com/PaddlePaddle/PaddleOCR/blob/fbba2178d7093f1dffca65a5b963ec277f1a6125/ppocr/postprocess/rec_postprocess.py#L70
        """
        word_list = []
        word_col_list = []
        state_list = []

        word_content = []
        word_col_content = []

        valid_col = np.where(selection)[0]
        if len(valid_col) <= 0:
            return WordInfo()

        col_width = np.zeros(valid_col.shape)
        col_width[1:] = valid_col[1:] - valid_col[:-1]
        col_width[0] = min(3 if has_chinese_char(text[0]) else 2, int(valid_col[0]))

        state = None
        for c_i, char in enumerate(text):
            if char.isspace():
                if word_content:
                    word_list.append(word_content)
                    word_col_list.append(word_col_content)
                    state_list.append(state)
                    word_content = []
                    word_col_content = []
                continue

            c_state = WordType.CN if has_chinese_char(char) else WordType.EN_NUM
            if state is None:
                state = c_state

            if state != c_state or col_width[c_i] > 5:
                if len(word_content) != 0:
                    word_list.append(word_content)
                    word_col_list.append(word_col_content)
                    state_list.append(state)
                    word_content = []
                    word_col_content = []
                state = c_state

            word_content.append(char)
            word_col_content.append(int(valid_col[c_i]))

        if len(word_content) != 0:
            word_list.append(word_content)
            word_col_list.append(word_col_content)
            state_list.append(state)

        return WordInfo(words=word_list, word_cols=word_col_list, word_types=state_list)

    @staticmethod
    def get_ignored_tokens() -> List[int]:
        return [0]  # for ctc blank