A script to count relevant characters in a class of conference paper pdfs

charcount.py

# run as `python charcount.py <pdf file name>`

"""
    A script to count relevant characters in a class of conference paper pdfs

    This script assumes the pdf is generated with LaTeX from a conference
    template that includes the introduction as the first numbered section
    and a reference list generated using Bib(La)TeX.
    (Papers from UAI 2021 for example typically satisfy these criteria.)

    It returns the characters counted for pages starting from the one with
    the introduction and ending with the last page before the first reference
    entry, and the total character count over all pages.

    Pages with atypically low number of characters may correspond to those
    with a relatively large fraction of graphical content. Pages with
    atypically high number of characters may indicate text extraction errors
    (PyPDF2 does a decent job, but is not perfect).
"""

import PyPDF2
import sys
import re

pdf = PyPDF2.PdfReader(sys.argv[-1])  # argv[-1] should be <pdf file name>

intro_destination = pdf.named_destinations["section.1"]
page_to_start_counting = pdf.get_destination_page_number(intro_destination)

for name in pdf.named_destinations:
    if name.startswith("cite"):
        first_ref_destination = pdf.named_destinations[name]
        break
page_to_end_counting = pdf.get_destination_page_number(first_ref_destination)

total_characters = 0
for k in range(page_to_start_counting, page_to_end_counting):
    text = pdf.pages[k].extract_text()
    # print(text)  # useful for investigating text extraction quality
    characters = len(
        # remove whitespace from string of characters
        re.sub(r"\s+", "", text, flags=re.UNICODE)
    )
    print(f"page {k+1}: {characters}")
    total_characters += characters
print(f"all counted pages: {total_characters}")