Merging PDF files with Python3

Question

I am writing a small script that needs to merge many one-page pdf files. I want the script to run with Python3 and to have as few dependencies as possible.

For the PDF merging part, I tried using PyPdf. However, the Python 3 support seems to be buggy; It can’t handle inkscape generated PDF files (which I need). I have the current git version of PyPdf installed, and the following test script doesn’t work:

import PyPDF2

output_pdf = PyPDF2.PdfFileWriter()

with open("testI.pdf", "rb") as input:
    input_pdf = PyPDF2.PdfFileReader(input)
    output_pdf.addPage(input_pdf.getPage(0))

with open("test.pdf", "wb") as output:
    output_pdf.write(output)

It throws the following stack trace:

Traceback (most recent call last):
  File "test.py", line 7, in <module>
    output.addPage(input.getPage(0))
  File "/usr/lib/python3.3/site-packages/pyPdf/pdf.py", line 420, in getPage
    self._flatten()
  File "/usr/lib/python3.3/site-packages/pyPdf/pdf.py", line 574, in _flatten
    self._flatten(page.getObject(), inherit)
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 165, in getObject
    return self.pdf.getObject(self).getObject()
  File "/usr/lib/python3.3/site-packages/pyPdf/pdf.py", line 616, in getObject
    retval = readObject(self.stream, self)
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 66, in readObject
    return DictionaryObject.readFromStream(stream, pdf)
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 526, in readFromStream
    value = readObject(stream, pdf)
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 57, in readObject
    return ArrayObject.readFromStream(stream, pdf)
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 152, in readFromStream
    obj = readObject(stream, pdf)
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 86, in readObject
    return NumberObject.readFromStream(stream)
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 231, in readFromStream
    return FloatObject(name.decode("ascii"))
  File "/usr/lib/python3.3/site-packages/pyPdf/generic.py", line 207, in __new__
    return decimal.Decimal.__new__(cls, str(value), context)
TypeError: optional argument must be a context

The same script, however, works flawlessly with Python 2.7.

What am I doing wrong here? Is it a bug in the library? Can I work around it without touching the PyPDF library?

Asked By: janoliver

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Source

Answer 1

Just to make sure you are aware of already existing tools that do exactly this:

PDFtk
PDFjam (my favourite, requires LaTeX though)
Directly with GhostScript:
gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=finished.pdf file1.pdf file2.pdf

Answered By: Michael Wild

Answer 2

So I found the answer. The decimal.Decimal module in Python3.3 shows some weird behaviour. This is the corresponding StackOverflow question: Instantiate Decimal class I added some workaround to the PyPDF2 library and submitted a pull request.

Answered By: janoliver

Merging PDF files with Python3

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