extraction of text from pdf with pdfminer gives multiple copies

问题

I am trying to extract text from a PDF file using PDFMiner (the code found at Extracting text from a PDF file using PDFMiner in python?). I didn't change the code except path/to/pdf. Surprisingly, the code returns several copies of the same document. I got the same result with other pdf files. Do I need to pass other arguments or I am missing something? Any help is highly appreciated. Just in case, I provide the code:

from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from pdfminer.pdfpage import PDFPage
from cStringIO import StringIO

def convert_pdf_to_txt(path):
    rsrcmgr = PDFResourceManager()
    retstr = StringIO()
    codec = 'utf-8'
    laparams = LAParams()
    device = TextConverter(rsrcmgr, retstr, codec=codec, laparams=laparams)
    fp = file(path, 'rb')
    interpreter = PDFPageInterpreter(rsrcmgr, device)
    password = ""
    maxpages = 0
    caching = True
    pagenos=set()
    fstr = ''
    for page in PDFPage.get_pages(fp, pagenos, maxpages=maxpages,    password=password,caching=caching, check_extractable=True):
        interpreter.process_page(page)

        str = retstr.getvalue()
        fstr += str

    fp.close()
    device.close()
    retstr.close()
    return fstr

print convert_pdf_to_txt("test.pdf")

回答1:

My answer was a bit incorrect in the thread that you are referencing. I found the bug and forgot to update my answer.

Because the documentation is pretty sparse with pdfminer, I'm not able to fully explain why this works the way it does. Hopefully someone who knows the pdfminer library a bit better can give us some insight.

All I know is that you have to do text = retstr.getvalue() outside of the for loop. I can only assume that retstr is being updated as if we were doing final_text += text inside the for loop, so once it's all finished we just have to do text = retstr.getvalue() to get the text from all the pages.

from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from pdfminer.pdfpage import PDFPage
from cStringIO import StringIO

def convert_pdf_to_txt(path):
    rsrcmgr = PDFResourceManager()
    retstr = StringIO()
    codec = 'utf-8'
    laparams = LAParams()
    device = TextConverter(rsrcmgr, retstr, codec=codec, laparams=laparams)
    fp = file(path, 'rb')
    interpreter = PDFPageInterpreter(rsrcmgr, device)
    password = ""
    maxpages = 0
    caching = True
    pagenos=set()
    for page in PDFPage.get_pages(fp, pagenos, maxpages=maxpages,password=password,caching=caching, check_extractable=True):

        interpreter.process_page(page)

    text = retstr.getvalue()

    fp.close()
    device.close()
    retstr.close()
    return text

print convert_pdf_to_txt("test.pdf")

Hope this helped!

回答2:

For python 3, DuckPuncher's code needs just a small adjustment:

import io
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from pdfminer.pdfpage import PDFPage

def convert_pdf_to_txt(path):
    rsrcmgr = PDFResourceManager()
    retstr = io.StringIO()
    codec = 'utf-8'
    laparams = LAParams()
    device = TextConverter(rsrcmgr, retstr, codec=codec, laparams=laparams)
    fp = open(path, 'rb')
    interpreter = PDFPageInterpreter(rsrcmgr, device)
    password = ""
    maxpages = 0
    caching = True
    pagenos=set()
    for page in PDFPage.get_pages(fp, pagenos, maxpages=maxpages,password=password,caching=caching, check_extractable=True):
        interpreter.process_page(page)

    text = retstr.getvalue()

    fp.close()
    device.close()
    retstr.close()
    return text

来源：https://stackoverflow.com/questions/26748788/extraction-of-text-from-pdf-with-pdfminer-gives-multiple-copies

标签

python

pdf

pdfminer