Grok Bot
66 lines
2.2 KiB
Python
66 lines
2.2 KiB
Python
"""Recognize the non-text parts of a page: running header, page number, figure caption."""
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import re
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from difflib import SequenceMatcher
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CAPTION_RE = re.compile(r"^\s*(LEFT|RIGHT|ABOVE|BELOW|OPPOSITE|FACING)\s*:\s*([A-Z][A-Z .,'\-]+?)\s*$")
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_NUM_LEAD = re.compile(r"^\s*(\d{1,3})\s{2,}(\S.*)$")
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_NUM_TRAIL = re.compile(r"^(.*\S)\s{2,}(\d{1,3})\s*$")
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_NUM_ONLY = re.compile(r"^\s*(\d{1,3})\s*$")
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def norm(text):
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return re.sub(r"[^a-z]", "", text.lower())
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def similar(a, b):
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return SequenceMatcher(None, norm(a), norm(b)).ratio()
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def header_zone(lines, title):
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"""The running header at the top of a unit.
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Returns (first_line, last_line_exclusive, page_number or None) or None.
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A header is the first block of lines (up to a blank line) that either carries a page number
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next to uppercase text, or reads as the book title."""
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i = 0
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while i < len(lines) and not lines[i].strip():
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i += 1
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j = i
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while j < len(lines) and lines[j].strip():
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j += 1
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zone = lines[i:j]
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if not zone:
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return None
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number, rest = None, []
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for ln in zone:
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m = _NUM_LEAD.match(ln) or None
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if m and number is None:
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number, rest = int(m.group(1)), rest + [m.group(2)]
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continue
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m = _NUM_TRAIL.match(ln)
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if m and number is None:
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number, rest = int(m.group(2)), rest + [m.group(1)]
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continue
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m = _NUM_ONLY.match(ln)
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if m and number is None:
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number = int(m.group(1))
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continue
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rest.append(ln)
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text = " ".join(rest)
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letters = [c for c in text if c.isalpha()]
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mostly_upper = (not letters) or sum(c.isupper() for c in letters) / len(letters) > 0.7
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if number is not None and mostly_upper and len(zone) <= 3:
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return i, j, number
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if title and similar(text, title) >= 0.9:
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return i, j, None
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return None
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def footer_number(lines):
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"""A lone page number as the last non-empty line. Returns (line_index, number) or None."""
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k = len(lines) - 1
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while k >= 0 and not lines[k].strip():
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k -= 1
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if k >= 0 and _NUM_ONLY.match(lines[k]):
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return k, int(lines[k])
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return None
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