Update OCR module

AUTHORS.md

@@ -22,4 +22,6 @@
 
 [Shangzi Xue](https://github.com/ShangziXue)
 
+[Heng Yu](https://github.com/GNEHUY)
+
 The stared contributors are the corresponding authors. 

EduNLP/SIF/parser/ocr.py

@@ -0,0 +1,156 @@
+# coding: utf-8
+# 2024/3/5 @ yuheng
+import json
+import requests
+from EduNLP.utils import image2base64
+
+
+class FormulaRecognitionError(Exception):
+    """Exception raised when formula recognition fails."""
+    def __init__(self, message="Formula recognition failed"):
+        self.message = message
+        super().__init__(self.message)
+
+
+def ocr_formula_figure(image_PIL_or_base64, is_base64=False):
+    """
+    Recognizes mathematical formulas in an image and returns their LaTeX representation.
+
+    Parameters
+    ----------
+    image_PIL_or_base64 : PngImageFile or str
+        The PngImageFile if is_base64 is False, or the base64 encoded string of the image if is_base64 is True.
+    is_base64 : bool, optional
+        Indicates whether the image_PIL_or_base64 parameter is an PngImageFile or a base64 encoded string.
+
+    Returns
+    -------
+    latex : str
+        The LaTeX representation of the mathematical formula recognized in the image.
+        Raises an exception if the image is not recognized as containing a mathematical formula.
+
+    Raises
+    ------
+    FormulaRecognitionError
+        If the HTTP request does not return a 200 status code,
+        if there is an error processing the response,
+        if the image is not recognized as a mathematical formula.
+
+    Examples
+    --------
+    >>> import os
+    >>> from PIL import Image
+    >>> from EduNLP.utils import abs_current_dir, path_append
+    >>> img_dir = os.path.abspath(path_append(abs_current_dir(__file__), "..", "..", "..", "asset", "_static"))
+    >>> image_PIL = Image.open(path_append(img_dir, "item_ocr_formula.png", to_str=True))
+    >>> print(ocr_formula_figure(image_PIL))
+    f(x)=\\left (\\frac {1}{3}\\right )^{x}-\\sqrt {x}}
+    >>> import os
+    >>> from PIL import Image
+    >>> from EduNLP.utils import abs_current_dir, path_append, image2base64
+    >>> img_dir = os.path.abspath(path_append(abs_current_dir(__file__), "..", "..", "..", "asset", "_static"))
+    >>> image_PIL = Image.open(path_append(img_dir, "item_ocr_formula.png", to_str=True))
+    >>> image_base64 = image2base64(image_PIL)
+    >>> print(ocr_formula_figure(image_base64, is_base64=True))
+    f(x)=\\left (\\frac {1}{3}\\right )^{x}-\\sqrt {x}}
+
+    Notes
+    -----
+    This function relies on an external service "https://formula-recognition-service-47-production.env.iai.bdaa.pro/v1",
+    and the `requests` library to make HTTP requests. Make sure the required libraries are installed before use.
+    """
+    url = "https://formula-recognition-service-47-production.env.iai.bdaa.pro/v1"
+
+    if is_base64:
+        image = image_PIL_or_base64
+    else:
+        image = image2base64(image_PIL_or_base64)
+
+    data = [{
+        'qid': 0,
+        'image': image
+    }]
+
+    resp = requests.post(url, data=json.dumps(data))
+
+    if resp.status_code != 200:
+        raise FormulaRecognitionError(f"HTTP error {resp.status_code}: {resp.text}")
+
+    try:
+        res = json.loads(resp.content)
+    except Exception as e:
+        raise FormulaRecognitionError(f"Error processing response: {e}")
+
+    res = json.loads(resp.content)
+    data = res['data']
+    if data['success'] == 1 and data['is_formula'] == 1 and data['detect_formula'] == 1:
+        latex = data['latex']
+    else:
+        latex = None
+        raise FormulaRecognitionError("Image is not recognized as a formula")
+
+    return latex
+
+
+def ocr(src, is_base64=False, figure_instances: dict = None):
+    """
+    Recognizes mathematical formulas within figures from a given source,
+    which can be either a base64 string or an identifier for a figure within a provided dictionary.
+
+    Parameters
+    ----------
+    src : str
+        The source from which the figure is to be recognized.
+        It can be a base64 encoded string of the image if is_base64 is True,
+        or an identifier for the figure if is_base64 is False.
+    is_base64 : bool, optional
+        Indicates whether the src parameter is a base64 encoded string or an identifier, by default False.
+    figure_instances : dict, optional
+        A dictionary mapping figure identifiers to their corresponding PngImageFile, by default None.
+        This is only required and used if is_base64 is False.
+
+    Returns
+    -------
+    forumla_figure_latex : str or None
+        The LaTeX representation of the mathematical formula recognized within the figure.
+        Returns None if no formula is recognized or
+        if the figure_instances dictionary does not contain the specified figure identifier when is_base64 is False.
+
+    Examples
+    --------
+    >>> import os
+    >>> from PIL import Image
+    >>> from EduNLP.utils import abs_current_dir, path_append
+    >>> img_dir = os.path.abspath(path_append(abs_current_dir(__file__), "..", "..", "..", "asset", "_static"))
+    >>> image_PIL = Image.open(path_append(img_dir, "item_ocr_formula.png", to_str=True))
+    >>> figure_instances = {"1": image_PIL}
+    >>> src_id = r"$\\FormFigureID{1}$"
+    >>> print(ocr(src_id[1:-1], figure_instances=figure_instances))
+    f(x)=\\left (\\frac {1}{3}\\right )^{x}-\\sqrt {x}}
+    >>> import os
+    >>> from PIL import Image
+    >>> from EduNLP.utils import abs_current_dir, path_append, image2base64
+    >>> img_dir = os.path.abspath(path_append(abs_current_dir(__file__), "..", "..", "..", "asset", "_static"))
+    >>> image_PIL = Image.open(path_append(img_dir, "item_ocr_formula.png", to_str=True))
+    >>> image_base64 = image2base64(image_PIL)
+    >>> src_base64 = r"$\\FormFigureBase64{%s}$" % (image_base64)
+    >>> print(ocr(src_base64[1:-1], is_base64=True, figure_instances=True))
+    f(x)=\\left (\\frac {1}{3}\\right )^{x}-\\sqrt {x}}
+
+    Notes
+    -----
+    This function relies on `ocr_formula_figure` for the actual OCR (Optical Character Recognition) process.
+    Ensure that `ocr_formula_figure` is correctly implemented and can handle base64 encoded strings and PngImageFile.
+    """
+    forumla_figure_latex = None
+    if is_base64:
+        figure = src[len(r"\FormFigureBase64") + 1: -1]
+        if figure_instances is not None:
+            forumla_figure_latex = ocr_formula_figure(figure, is_base64)
+    else:
+        figure = src[len(r"\FormFigureID") + 1: -1]
+        if figure_instances is not None:
+            figure = figure_instances[figure]
+            forumla_figure_latex = ocr_formula_figure(figure, is_base64)
+
+    return forumla_figure_latex

EduNLP/SIF/segment/segment.py

@@ -5,6 +5,7 @@
 import re
 from contextlib import contextmanager
 from ..constants import Symbol, TEXT_SYMBOL, FORMULA_SYMBOL, FIGURE_SYMBOL, QUES_MARK_SYMBOL, TAG_SYMBOL, SEP_SYMBOL
+from ..parser.ocr import ocr
 
 
 class TextSegment(str):
@@ -93,7 +94,7 @@ class SegmentList(object):
     >>> SegmentList(test_item)
     ['如图所示，则三角形', 'ABC', '的面积是', '\\\\SIFBlank', '。', \\FigureID{1}]
     """
-    def __init__(self, item, figures: dict = None):
+    def __init__(self, item, figures: dict = None, convert_image_to_latex=False):
         self._segments = []
         self._text_segments = []
         self._formula_segments = []
@@ -112,9 +113,15 @@ def __init__(self, item, figures: dict = None):
             if not re.match(r"\$.+?\$", segment):
                 self.append(TextSegment(segment))
             elif re.match(r"\$\\FormFigureID\{.+?}\$", segment):
-                self.append(FigureFormulaSegment(segment[1:-1], is_base64=False, figure_instances=figures))
+                if convert_image_to_latex:
+                    self.append(LatexFormulaSegment(ocr(segment[1:-1], is_base64=False, figure_instances=figures)))
+                else:
+                    self.append(FigureFormulaSegment(segment[1:-1], is_base64=False, figure_instances=figures))
             elif re.match(r"\$\\FormFigureBase64\{.+?}\$", segment):
-                self.append(FigureFormulaSegment(segment[1:-1], is_base64=True, figure_instances=figures))
+                if convert_image_to_latex:
+                    self.append(LatexFormulaSegment(ocr(segment[1:-1], is_base64=True, figure_instances=figures)))
+                else:
+                    self.append(FigureFormulaSegment(segment[1:-1], is_base64=True, figure_instances=figures))
             elif re.match(r"\$\\FigureID\{.+?}\$", segment):
                 self.append(FigureSegment(segment[1:-1], is_base64=False, figure_instances=figures))
             elif re.match(r"\$\\FigureBase64\{.+?}\$", segment):
@@ -271,7 +278,7 @@ def describe(self):
         }
 
 
-def seg(item, figures=None, symbol=None):
+def seg(item, figures=None, symbol=None, convert_image_to_latex=False):
     r"""
     It is a interface for SegmentList. And show it in an appropriate way.
 
@@ -346,7 +353,7 @@ def seg(item, figures=None, symbol=None):
     >>> s2.text_segments
     ['已知', '，则以下说法中正确的是']
     """
-    segments = SegmentList(item, figures)
+    segments = SegmentList(item, figures, convert_image_to_latex)
     if symbol is not None:
         segments.symbolize(symbol)
     return segments

tests/test_sif/test_ocr.py

@@ -0,0 +1,62 @@
+# 2024/3/5 @ yuheng
+
+import pytest
+import json
+
+from EduNLP.SIF.segment import seg
+from EduNLP.SIF.parser.ocr import ocr_formula_figure, FormulaRecognitionError
+from unittest.mock import patch
+
+
+def test_ocr(figure0, figure1, figure0_base64, figure1_base64):
+    seg(
+        r"如图所示，则$\FormFigureID{0}$的面积是$\SIFBlank$。$\FigureID{1}$",
+        figures={
+            "0": figure0,
+            "1": figure1
+        },
+        convert_image_to_latex=True
+    )
+    s = seg(
+        r"如图所示，则$\FormFigureBase64{%s}$的面积是$\SIFBlank$。$\FigureBase64{%s}$" % (figure0_base64, figure1_base64),
+        figures=True,
+        convert_image_to_latex=True
+    )
+    with pytest.raises(TypeError):
+        s.append("123")
+    seg_test_text = seg(
+        r"如图所示，有三组$\textf{机器人,bu}$在踢$\textf{足球,b}$",
+        figures=True
+    )
+    assert seg_test_text.text_segments == ['如图所示，有三组机器人在踢足球']
+
+
+def test_ocr_formula_figure_exceptions(figure0_base64):
+    """Simulate a non-200 status code"""
+    with patch('EduNLP.SIF.parser.ocr.requests.post') as mock_post:
+        mock_post.return_value.status_code = 404
+        with pytest.raises(FormulaRecognitionError) as exc_info:
+            ocr_formula_figure(figure0_base64, is_base64=True)
+        assert "HTTP error 404" in str(exc_info.value)
+
+    """Simulate an invalid JSON response"""
+    with patch('EduNLP.SIF.parser.ocr.requests.post') as mock_post:
+        mock_post.return_value.status_code = 200
+        mock_post.return_value.content = b"invalid_json_response"
+        with pytest.raises(FormulaRecognitionError) as exc_info:
+            ocr_formula_figure(figure0_base64, is_base64=True)
+        assert "Error processing response" in str(exc_info.value)
+
+    """Simulate image not recognized as a formula"""
+    with patch('EduNLP.SIF.parser.ocr.requests.post') as mock_post:
+        mock_post.return_value.status_code = 200
+        mock_post.return_value.content = json.dumps({
+            "data": {
+                'success': 1,
+                'is_formula': 0,
+                'detect_formula': 0
+            }
+        }).encode('utf-8')
+        with pytest.raises(FormulaRecognitionError) as exc_info:
+            ocr_formula_figure(figure0_base64, is_base64=True)
+        assert "Image is not recognized as a formula" in str(exc_info.value)