exam-segment-django/segment/formula/formula_segment.py

# @Author  : lightXu
# @File    : formula_segment.py
# @Time    : 2019/1/24 0024 下午 13:24
import time
import re
import copy
import math
import cv2
import numpy as np
import xml.etree.cElementTree as ET
from segment.formula import mathpix_ocr
from segment.server import get_ocr_text_and_coordinate_formula
from segment.image_operation import utils


def get_coordinates(word_res, formula_words_list):
    res_list = []
    for formula_raw in formula_words_list:
        coordinates_start_index = formula_raw[1][0]
        coordinates_end_index = formula_raw[1][1] - 1
        coordinates_start = word_res['chars'][coordinates_start_index]['location']
        coordinates_end = word_res['chars'][coordinates_end_index]['location']
        coordinates = (coordinates_start['left'],  # xmin
                       min(coordinates_start['top'], coordinates_end['top']),  # ymin
                       coordinates_end['left'] + coordinates_end['width'],  # xmax
                       max(coordinates_start['top'] + coordinates_start['height'],
                           coordinates_end['top'] + coordinates_end['height']))  # ymax
        tmp_dict = {'chars': formula_raw[0],
                    'raw_chars': formula_raw[0],
                    'coordinates': coordinates,
                    'middle': (coordinates[0] + int((coordinates[2] - coordinates[0]) // 2),
                               coordinates[1] + int((coordinates[3] - coordinates[1]) // 2))}
        res_list.append(tmp_dict)
    return res_list


def generate_char(words, index_pair, zh=True):
    if index_pair:
        # new_words = words.copy()
        length = index_pair[1] - index_pair[0]
        gen = ''
        if zh:
            for i in range(length):
                gen = '中' + gen
        else:
            for i in range(length):
                gen = 'F' + gen
        words = words.replace(words[index_pair[0]:index_pair[1]], gen)
        return words
    else:
        return words


def segment(img, save_path, access_token):
    # raw_img = img.copy()
    # img = utils.preprocess(raw_img, None)

    word_result_list = get_ocr_text_and_coordinate_formula(img, access_token)
    formula_coordinates_dict_list = []
    zh_coordinates_dict_list = []
    zh_char_height = 20  # default
    zh_char_width = 15  # default
    zh_char_height_list = []
    zh_char_width_list = []

    exclude = r'{}|{}|{}|{}|{}|{}'.format(
        '^[(（]*[\d]+[）)]',
        '[ABCD]\.',
        '[\u4e00-\u9fa5][，；：。,;:.]',
        '[①②③④⑤⑥⑦⑧⑨⑩]',
        '[(（][）)]',
        '[\u4e00-\u9fa5][\d]+[\u4e00-\u9fa5]')

    for index, word_res in enumerate(word_result_list):
        words = word_res['words'].replace(' ', '').replace('兀', 'π')  # 去除空格，baidu_api bug
        abcd_words_m = re.finditer(exclude, words)
        abcd_index_list = [(m.group(), m.span()) for m in abcd_words_m if m]

        words_tmp_zh = copy.copy(words)
        for ele in abcd_index_list:
            words_tmp_zh = generate_char(words_tmp_zh, ele[1], zh=True)

        formula_words_m = re.finditer(r'[^\u4e00-\u9fa5._"“”]+', words_tmp_zh)
        formula_index_list = [(m.group(), m.span()) for m in formula_words_m if m]
        formula_list = get_coordinates(word_res, formula_index_list)
        formula_coordinates_dict_list = formula_coordinates_dict_list + formula_list

        words_tmp_formula = copy.copy(words)
        for ele in abcd_index_list:
            words_tmp_formula = generate_char(words_tmp_formula, ele[1], zh=False)
        zh_words_m = re.finditer(r'[\u4e00-\u9fa5._"“”]+', words_tmp_formula)
        zh_index_list = [(m.group(), m.span()) for m in zh_words_m if m]
        zh_list = get_coordinates(word_res, zh_index_list + abcd_index_list)
        zh_coordinates_dict_list = zh_coordinates_dict_list + zh_list

        one_zh_char_m = re.match(r'[\u4e00-\u9fa5]+', words)
        if one_zh_char_m:
            index = one_zh_char_m.span()[0]
            zh_char_height_list.append(word_res['chars'][index]['location']['height'])
            zh_char_width_list.append(word_res['chars'][index]['location']['width'])

    if len(zh_char_width_list) > 0 and len(zh_char_height_list) > 0:
        zh_char_height = np.mean(zh_char_height_list)
        zh_char_width = np.mean(zh_char_width_list)

    formula_coordinates_list = [ele['coordinates'] for ele in formula_coordinates_dict_list]
    formula_combine_list = combine(formula_coordinates_list, zh_char_height, zh_char_width)  # 欧式距离

    formula_combine_dict_list = []
    for i, ele in enumerate(formula_combine_list):
        middle = (ele[0] + int((ele[2] - ele[0]) // 2), ele[1] + int((ele[3] - ele[1]) // 2))
        ocr_region = utils.crop_region_direct(img, ele)
        y, x = ocr_region.shape[0], ocr_region.shape[1]
        if min(y, x) <= 50:
            ocr_region = utils.resize_by_percent(ocr_region, 2.00)  # 放大若干倍
        try:
            mathpix_raw_chars, latex_confidence = mathpix_ocr.mathpix_api(ocr_region)  # 识别公式
            render_mathpix_chars = '<latex>{}</latex>'.format(mathpix_raw_chars)
            if latex_confidence < 0.2:
                for item in formula_coordinates_dict_list:
                    if ele == item['coordinates']:
                        mathpix_raw_chars = item['chars']
                        render_mathpix_chars = '<latex>{}</latex>'.format(item['chars'])
                        break

        except Exception:
            render_mathpix_chars = 'formula'
            mathpix_raw_chars = 'formula'
            for item in formula_coordinates_dict_list:
                if ele == item['coordinates']:
                    mathpix_raw_chars = item['chars']
                    render_mathpix_chars = '<latex>{}</latex>'.format(item['chars'])
                    break

        # print(render_mathpix_chars)
        tmp_dict = {'chars': render_mathpix_chars, 'middle': middle, 'coordinates': ele, 'raw_chars': mathpix_raw_chars}
        formula_combine_dict_list.append(tmp_dict)

    # res_dict = {'formula': formula_combine_list, 'zh_chars': zh_coordinates_dict_list}
    all_dict_list = formula_combine_dict_list + zh_coordinates_dict_list

    all_dict_list = sorted(all_dict_list, key=lambda k: k.get('middle')[1])

    # 相邻y做差
    former = np.array([ele['middle'][1] for ele in all_dict_list[:-1]])
    rear = np.array([ele['middle'][1] for ele in all_dict_list[1:]])
    dif = rear - former
    split_x_index = [index for index, ele in enumerate(dif) if ele >= zh_char_height]  # y轴排序

    if not split_x_index:
        all_dict_list = sorted(all_dict_list, key=lambda k: k.get('middle')[0])  # x轴排序
        lines = [ele['chars'] for ele in all_dict_list]
        raw_lines = [ele['raw_chars'] for ele in all_dict_list]
        return lines, raw_lines
    else:
        res_list = []
        split_x_index = [ele + 1 for ele in split_x_index]  # 索引值扩大
        split_x_index.insert(0, 0)
        split_x_index.insert(-1, len(all_dict_list))
        split_x_index = sorted(list(set(split_x_index)))
        for i, split in enumerate(split_x_index[1:]):
            one_line = all_dict_list[split_x_index[i]:split_x_index[i + 1]]
            one_line = sorted(one_line, key=lambda k: k.get('middle')[0])  # x轴排序
            res_list.append(one_line)

        lines = []
        raw_lines = []
        for ele in res_list:
            line_chars = ''
            raw_lines_chars = ''
            for ele1 in ele:
                chars = ele1['chars']
                raw_chars = ele1['raw_chars']
                line_chars = line_chars + chars
                raw_lines_chars = raw_lines_chars + raw_chars

            lines.append(line_chars + '\n')
            raw_lines.append(raw_lines_chars + '\n')
        # print(lines)

        return lines, raw_lines


def combine(formula_coordinates_list, zh_char_height, zh_char_width):
    formula_coordinates_list = sorted(formula_coordinates_list, key=lambda k: k[0])
    formula_coordinates_list = sorted(formula_coordinates_list, key=lambda k: k[1])  # 先x轴，再y轴排序

    recursion_flag = False
    del_list = []
    temp_list = formula_coordinates_list.copy()

    for i, outer in enumerate(temp_list):  # xmin, ymin, xmax, ymax
        for j, inner in enumerate(temp_list):  # xmin, ymin, xmax, ymax
            if not i == j:
                min_distance, flag = get_min_distance(outer, inner)
                combine_coordinate = ()
                if flag == 'i':
                    recursion_flag = True
                    combine_coordinate = (min(outer[0], inner[0]), min(outer[1], inner[1]),
                                          max(outer[2], inner[2]), max(outer[3], inner[3]))
                elif flag == 'h' and min_distance <= 1:
                    recursion_flag = True
                    combine_coordinate = (min(outer[0], inner[0]), min(outer[1], inner[1]),
                                          max(outer[2], inner[2]), max(outer[3], inner[3]))
                elif flag == 'w' and min_distance <= zh_char_width:
                    recursion_flag = True
                    combine_coordinate = (min(outer[0], inner[0]), min(outer[1], inner[1]),
                                          max(outer[2], inner[2]), max(outer[3], inner[3]))
                elif flag == 'c' and min_distance <= 1:
                    recursion_flag = True
                    combine_coordinate = (min(outer[0], inner[0]), min(outer[1], inner[1]),
                                          max(outer[2], inner[2]), max(outer[3], inner[3]))

                if combine_coordinate:
                    if not combine_coordinate == outer and not combine_coordinate == inner:  # 避免全包围的情况
                        del_list.append(outer)
                        del_list.append(inner)
                    if combine_coordinate == outer:
                        del_list.append(inner)
                    if combine_coordinate == inner:
                        del_list.append(outer)
                    formula_coordinates_list.append(combine_coordinate)

    res = list(set(formula_coordinates_list) - set(del_list))

    if recursion_flag:
        return combine(res, zh_char_height, zh_char_width)
    else:
        return res


def get_min_distance_square(coordinate1, coordinate2):  # 顶点间欧式距离最小值的平方和
    all_points1 = [(x, y) for x in [coordinate1[0], coordinate1[2]] for y in [coordinate1[1], coordinate1[3]]]
    all_points2 = [(x, y) for x in [coordinate2[0], coordinate2[2]] for y in [coordinate2[1], coordinate2[3]]]
    distance_list = []
    for index1, point1 in enumerate(all_points1):
        for index2, point2 in enumerate(all_points2):
            distance = (point1[0] - point2[0]) ** 2 + (point1[1] - point2[1]) ** 2
            distance_list.append(distance)
    min_distance = min(distance_list)
    return min_distance


def get_min_distance(coordinate1, coordinate2):  # 欧式距离最小值

    def dist(point1, point2):
        distance = (point1[0] - point2[0]) ** 2 + (point1[1] - point2[1]) ** 2
        return math.sqrt(distance)

    (x1, y1, x1b, y1b) = coordinate1
    (x2, y2, x2b, y2b) = coordinate2
    left = x2b < x1  # 2在1的坐标左边
    right = x1b < x2  # 2在1的坐标右边
    bottom = y2b < y1  # 2在1的坐标下边
    top = y1b < y2  # 2在1的坐标上边
    if top and left:
        return dist((x1, y1b), (x2b, y2)), 'c'
    elif left and bottom:
        return dist((x1, y1), (x2b, y2b)), 'c'
    elif bottom and right:
        return dist((x1b, y1), (x2, y2b)), 'c'
    elif right and top:
        return dist((x1b, y1b), (x2, y2)), 'c'
    elif left:
        return x1 - x2b, 'w'
    elif right:
        return x2 - x1b, 'w'
    elif bottom:
        return y1 - y2b, 'h'
    elif top:
        return y2 - y1b, 'h'
    else:             # rectangles intersect
        return 0, 'i'