Working with PDF files in Python

All of you must be familiar with what PDFs are. In fact, they are one of the most important and widely used digital media. PDF stands for Portable Document Format. It uses .pdf extension. It is used to present and exchange documents reliably, independent of software, hardware, or operating system.
Invented by Adobe, PDF is now an open standard maintained by the International Organization for Standardization (ISO). PDFs can contain links and buttons, form fields, audio, video, and business logic.
In this article, we will learn, how we can do various operations like:

• Extracting text from PDF
• Rotating PDF pages
• Merging PDFs
• Splitting PDF
• Adding watermark to PDF pages

Installation:Using simple python scripts!
We will be using a third-party module, PyPDF2.
PyPDF2 is a python library built as a PDF toolkit. It is capable of:

• Extracting document information (title, author, …)
• Splitting documents page by page
• Merging documents page by page
• Cropping pages
• Merging multiple pages into a single page
• Encrypting and decrypting PDF files
• and more!

To install PyPDF2, run the following command from the command line:

pip3 install PyPDF2

This module name is case-sensitive, so make sure the y is lowercase and everything else is uppercase. All the code and PDF files used in this tutorial/article are available here.

1. Extracting text from PDF file

Python

# importing required modules
import PyPDF2

# creating a pdf file object
pdfFileObj = open('example.pdf', 'rb')

# creating a pdf reader object
pdfReader = PyPDF2.PdfFileReader(pdfFileObj)

# printing number of pages in pdf file
print(pdfReader.numPages)

# creating a page object
pageObj = pdfReader.getPage(0)

# extracting text from page
print(pageObj.extractText())

# closing the pdf file object
pdfFileObj.close()

The output of the above program looks like this:

20
PythonBasics
S.R.Doty
August27,2008
Contents

1Preliminaries
4
1.1WhatisPython?...................................
..4
1.2Installationanddocumentation....................
.........4 [and some more lines...]

Let us try to understand the above code in chunks:

pdfFileObj = open('example.pdf', 'rb')

• We opened the example.pdf in binary mode.And saved the file object as pdfFileObj.

pdfReader = PyPDF2.PdfFileReader(pdfFileObj)

• Here, we create an object of PdfFileReader class of PyPDF2 module and pass the PDF file object & get a PDF reader object.

print(pdfReader.numPages)

• numPages property gives the number of pages in the PDF file. For example, in our case, it is 20 (see first line of output).

pageObj = pdfReader.getPage(0)

• Now, we create an object of PageObject class of PyPDF2 module. PDF reader object has function getPage() which takes page number (starting from index 0) as argument and returns the page object.

print(pageObj.extractText())

• Page object has function extractText() to extract text from the PDF page.

pdfFileObj.close()

• At last, we close the PDF file object.

Note: While PDF files are great for laying out text in a way that’s easy for people to print and read, they’re not straightforward for software to parse into plaintext. As such, PyPDF2 might make mistakes when extracting text from a PDF and may even be unable to open some PDFs at all. It isn’t much you can do about this, unfortunately. PyPDF2 may simply be unable to work with some of your particular PDF files.

2. Rotating PDF pages

Python

# importing the required modules
import PyPDF2

def PDFrotate(origFileName, newFileName, rotation):

# creating a pdf File object of original pdf
pdfFileObj = open(origFileName, 'rb')

# creating a pdf Reader object
pdfReader = PyPDF2.PdfFileReader(pdfFileObj)

# creating a pdf writer object for new pdf
pdfWriter = PyPDF2.PdfFileWriter()

# rotating each page
for page in range(pdfReader.numPages):

# creating rotated page object
pageObj = pdfReader.getPage(page)
pageObj.rotateClockwise(rotation)

# adding rotated page object to pdf writer
pdfWriter.addPage(pageObj)

# new pdf file object
newFile = open(newFileName, 'wb')

# writing rotated pages to new file
pdfWriter.write(newFile)

# closing the original pdf file object
pdfFileObj.close()

# closing the new pdf file object
newFile.close()


def main():

# original pdf file name
origFileName = 'example.pdf'

# new pdf file name
newFileName = 'rotated_example.pdf'

# rotation angle
rotation = 270

# calling the PDFrotate function
PDFrotate(origFileName, newFileName, rotation)

if __name__ == "__main__":
# calling the main function
main()

Here, you can see how the first page of rotated_example.pdf looks like ( right image) after rotation:

There is a tool called UPDF that can be used to Rotate a PDF.

Some important points related to the above code:

• For rotation, we first create a PDF reader object of the original PDF.

pdfWriter = PyPDF2.PdfFileWriter()

• Rotated pages will be written to a new PDF. For writing to PDFs, we use the object of PdfFileWriter class of PyPDF2 module.

for page in range(pdfReader.numPages):
        pageObj = pdfReader.getPage(page)
        pageObj.rotateClockwise(rotation)
        pdfWriter.addPage(pageObj)

• Now, we iterate each page of the original PDF. We get page object by getPage() method of PDF reader class. Now, we rotate the page by rotateClockwise() method of page object class. Then, we add a page to PDF writer object using addPage() method of PDF writer class by passing the rotated page object.

newFile = open(newFileName, 'wb')
pdfWriter.write(newFile)
pdfFileObj.close()
newFile.close()

• Now, we have to write the PDF pages to a new PDF file. Firstly, we open the new file object and write PDF pages to it using write() method of PDF writer object. Finally, we close the original PDF file object and the new file object.

3. Merging PDF files

Python

# importing required modules
import PyPDF2


def PDFmerge(pdfs, output):
# creating pdf file merger object
pdfMerger = PyPDF2.PdfFileMerger()

# appending pdfs one by one
for pdf in pdfs:
pdfmerger.append(pdf)

# writing combined pdf to output pdf file
with open(output, 'wb') as f:
pdfMerger.write(f)


def main():
# pdf files to merge
pdfs = ['example.pdf', 'rotated_example.pdf']

# output pdf file name
output = 'combined_example.pdf'

# calling pdf merge function
PDFmerge(pdfs=pdfs, output=output)


if __name__ == "__main__":
# calling the main function
main()

The output of the above program is a combined PDF, combined_example.pdf, obtained by merging example.pdf and rotated_example.pdf.

• Let us have a look at important aspects of this program:

pdfMerger = PyPDF2.PdfFileMerger()

• For merging, we use a pre-built class, PdfFileMerger of PyPDF2 module.
  Here, we create an object pdfMerger of PDF merger class

for pdf in pdfs:
        pdfmerger.append(open(focus, "rb"))

• Now, we append file object of each PDF to PDF merger object using the append() method.

with open(output, 'wb') as f:
        pdfMerger.write(f)

• Finally, we write the PDF pages to the output PDF file using write method of PDF merger object.

4. Splitting PDF file

Python

# importing the required modules
import PyPDF2

def PDFsplit(pdf, splits):
# creating input pdf file object
pdfFileObj = open(pdf, 'rb')

# creating pdf reader object
pdfReader = PyPDF2.PdfFileReader(pdfFileObj)

# starting index of first slice
start = 0

# starting index of last slice
end = splits[0]


for i in range(len(splits)+1):
# creating pdf writer object for (i+1)th split
pdfWriter = PyPDF2.PdfFileWriter()

# output pdf file name
outputpdf = pdf.split('.pdf')[0] + str(i) + '.pdf'

# adding pages to pdf writer object
for page in range(start,end):
pdfWriter.addPage(pdfReader.getPage(page))

# writing split pdf pages to pdf file
with open(outputpdf, "wb") as f:
pdfWriter.write(f)

# interchanging page split start position for next split
start = end
try:
# setting split end position for next split
end = splits[i+1]
except IndexError:
# setting split end position for last split
end = pdfReader.numPages

# closing the input pdf file object
pdfFileObj.close()

def main():
# pdf file to split
pdf = 'example.pdf'

# split page positions
splits = [2,4]

# calling PDFsplit function to split pdf
PDFsplit(pdf, splits)

if __name__ == "__main__":
# calling the main function
main()

Output will be three new PDF files with split 1 (page 0,1), split 2(page 2,3), split 3(page 4-end).
No new function or class has been used in the above python program. Using simple logic and iterations, we created the splits of passed PDF according to the passed list splits.

5. Adding watermark to PDF pages

Python

# importing the required modules
import PyPDF2

def add_watermark(wmFile, pageObj):
# opening watermark pdf file
wmFileObj = open(wmFile, 'rb')

# creating pdf reader object of watermark pdf file
pdfReader = PyPDF2.PdfFileReader(wmFileObj)

# merging watermark pdf's first page with passed page object.
pageObj.mergePage(pdfReader.getPage(0))

# closing the watermark pdf file object
wmFileObj.close()

# returning watermarked page object
return pageObj

def main():
# watermark pdf file name
mywatermark = 'watermark.pdf'

# original pdf file name
origFileName = 'example.pdf'

# new pdf file name
newFileName = 'watermarked_example.pdf'

# creating pdf File object of original pdf
pdfFileObj = open(origFileName, 'rb')

# creating a pdf Reader object
pdfReader = PyPDF2.PdfFileReader(pdfFileObj)

# creating a pdf writer object for new pdf
pdfWriter = PyPDF2.PdfFileWriter()

# adding watermark to each page
for page in range(pdfReader.numPages):
# creating watermarked page object
wmpageObj = add_watermark(mywatermark, pdfReader.getPage(page))

# adding watermarked page object to pdf writer
pdfWriter.addPage(wmpageObj)

# new pdf file object
newFile = open(newFileName, 'wb')

# writing watermarked pages to new file
pdfWriter.write(newFile)

# closing the original pdf file object
pdfFileObj.close()
# closing the new pdf file object
newFile.close()

if __name__ == "__main__":
# calling the main function
main()

Here is how the first page of original (left) and watermarked (right) PDF file looks like:

• All the process is same as the page rotation example. Only difference is:

wmpageObj = add_watermark(mywatermark, pdfReader.getPage(page))

• Page object is converted to watermarked page object using add_watermark() function.
• Let us try to understand add_watermark() function:

wmFileObj = open(wmFile, 'rb')
pdfReader = PyPDF2.PdfFileReader(wmFileObj) 
pageObj.mergePage(pdfReader.getPage(0))
wmFileObj.close()
return pageObj

• Foremost, we create a PDF reader object of watermark.pdf. To the passed page object, we use mergePage() function and pass the page object of the first page of the watermark PDF reader object. This will overlay the watermark over the passed page object.

And here we reach the end of this long tutorial on working with PDF files in python.
Now, you can easily create your own PDF manager!
References:

• https://automatetheboringstuff.com/chapter13/
• https://pythonhosted.org/PyPDF2/

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