Create a Single PDF with Multiple Graphviz Diagrams Using Python

Learn how to merge multiple Graphviz diagrams into a single PDF file using Python's PyPDF2 library. Create organized visualizations page by page!
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Merging Multiple Graphviz Diagrams into a Single PDF File

Are you working with intricate Graphviz diagrams in Python and finding it challenging to handle multiple diagrams at once? If you're looking to compile several diagrams into one cohesive PDF file with each diagram on a separate page, you're in the right place! In this guide, we will explore an effective solution using the PyPDF2 library to combine multiple Graphviz outputs into a single PDF document.

The Challenge of Multiple Graphviz Diagrams

Creating Graphviz diagrams can be straightforward when working with a single diagram; however, it becomes more complex when you need to visualize a series of diagrams together. For instance, you might find yourself wanting to generate multiple DOT files and then combine them into one PDF file—one page for each diagram. Unfortunately, the traditional method of calling network1.view(file_name) will only give you one PDF per diagram. So, how do we proceed?

The Solution: Using PyPDF2 to Merge PDFs

Step 1: Generate Your Graphviz Diagrams

First off, let's ensure we create our Graphviz diagrams correctly. You can start by creating your diagrams as shown below:

[[See Video to Reveal this Text or Code Snippet]]

Repeat this creation process for as many diagrams as you need (e.g., diagram2, diagram3, etc.). Once you have all your individual PDFs generated, it's time to merge them.

Step 2: Install PyPDF2

Before we start merging PDFs, make sure you have the PyPDF2 library installed. If you haven't done so, you can install it using pip:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Merging the PDFs

Now, let's dive into the coding part. Below is a complete example that demonstrates how to merge multiple PDF files into a single PDF document:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Open Your PDF Files: The code begins by opening each diagram PDF file in binary read mode.

Read PDFs: For each PDF file opened, the corresponding PdfFileReader object is created.

Create a PDF Writer: A PdfFileWriter object is instantiated to create a new PDF document.

Add Pages: Using a loop, all the pages from each PDF file are added to the writer.

Save the Final PDF: Finally, the merged PDF is written to a new file called merged_diagrams.pdf.

Clean Up: All opened files are closed to free up resources.

Conclusion

By following these steps, you can now easily create a single PDF file that includes multiple Graphviz diagrams, each residing on its own page. This solution not only streamlines your workflow but also enhances the presentation of your visual data! If you have further questions or any suggestions, feel free to drop a comment below.

Happy coding!