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, pypdf.
pypdf 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 pypdf, run the following command from the command line:
pip install pypdf
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
# importing required classes from pypdf import PdfReader
# creating a pdf reader object reader = PdfReader('example.pdf')
# printing number of pages in pdf file print(len(reader.pages))
# creating a page object page = reader.pages[0]
# extracting text from page print(page.extract_text())
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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:
reader = PdfReader('example.pdf')
-
Here, we create an object of PdfReader class of pypdf module and pass the path to the PDF file & get a PDF reader object.
print(len(reader.pages))
-
pages property gives the number of pages in the PDF file. For example, in our case, it is 20 (see first line of output).
pageObj = reader.pages[0]
-
Now, we create an object of PageObject class of pypdf module. PDF reader object has function pages[] which takes page number (starting from index 0) as argument and returns the page object.
print(pageObj.extract_text())
- Page object has function extract_text() to extract text from the PDF page.
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, pypdf 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. pypdf may simply be unable to work with some of your particular PDF files.
2. Rotating PDF pages
# importing the required classes from pypdf import PdfReader, PdfWriter
def PDFrotate(origFileName, newFileName, rotation):
# creating a pdf Reader object
reader = PdfReader(origFileName)
# creating a pdf writer object for new pdf
writer = PdfWriter()
# rotating each page
for page in range(len(reader.pages)):
# creating rotated page object
pageObj = reader.pages[page]
pageObj.rotate(rotation)
# adding rotated page object to pdf writer
pdfWriter.add_page(pageObj)
# new pdf file object
newFile = open(newFileName, 'wb')
# writing rotated pages to new file
pdfWriter.write(newFile)
# 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()
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Here, you can see how the first page of rotated_example.pdf looks like ( right image) after rotation:
Some important points related to the above code:
- For rotation, we first create a PDF reader object of the original PDF.
writer = PdfWriter()
- Rotated pages will be written to a new PDF. For writing to PDFs, we use the object of PdfWriter class of pypdf module.
for page in range(len(pdfReader.pages)):
pageObj = pdfReader.pages[page]
pageObj.rotate(rotation)
pdfWriter.add_page(pageObj)
- Now, we iterate each page of the original PDF. We get page object by .pages[] method of PDF reader class. Now, we rotate the page by rotate() method of page object class. Then, we add a page to PDF writer object using addage() method of PDF writer class by passing the rotated page object.
newFile = open(newFileName, 'wb')
pdfWriter.write(newFile)
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
# importing required modules from pypdf import PdfMerger
def PDFmerge(pdfs, output):
# creating pdf file merger object
pdfMerger = PdfMerger()
# 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()
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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 = PdfMerger()
-
For merging, we use a pre-built class, PdfMerger of pypdf 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
# importing the required modules from pypdf import PdfReader, PdfWriter
def PDFsplit(pdf, splits):
# creating pdf reader object
reader = PdfReader(pdf)
# 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
writer = PdfWriter()
# output pdf file name
outputpdf = pdf.split('.pdf')[0] + str(i) + '.pdf'
# adding pages to pdf writer object
for page in range(start,end):
writer.add_page(reader.pages[page])
# writing split pdf pages to pdf file
with open(outputpdf, "wb") as f:
writer.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 = len(reader.pages)
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()
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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
# importing the required modules from pypdf import PdfReader
def add_watermark(wmFile, pageObj):
# creating pdf reader object of watermark pdf file
reader = PdfReader(wmFileObj)
# merging watermark pdf's first page with passed page object.
pageObj.merge_page(reader.pages[0])
# 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
reader = PdfReader(pdfFileObj)
# creating a pdf writer object for new pdf
writer = PdfWriter()
# adding watermark to each page
for page in range(len(reader.pages)):
# creating watermarked page object
wmpageObj = add_watermark(mywatermark, reader.pages[page])
# adding watermarked page object to pdf writer
writer.add_page(wmpageObj)
# new pdf file object
newFile = open(newFileName, 'wb')
# writing watermarked pages to new file
writer.write(newFile)
# closing the new pdf file object
newFile.close()
if __name__ == "__main__":
# calling the main function
main()
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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.pages[page])
- Page object is converted to watermarked page object using add_watermark() function.
-
Let us try to understand add_watermark() function:
reader = PdfReader(wmFile)
pageObj.merge_page(reader.pages[0])
wmFileObj.close()
return pageObj
- Foremost, we create a PDF reader object of watermark.pdf. To the passed page object, we use merge_page() 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://pypi.org/project/pypdf/
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