How to use the command 'unflatten' (with examples)

The unflatten command is a tool within the Graphviz suite that addresses a common issue in visualizing directed graphs: the layout aspect ratio. When rendering graphs, especially complex ones, the layouts can become stretched, reducing clarity and making them difficult to interpret. The unflatten command preprocesses the graphs, adjusting them to improve their layout aspect ratio, thereby enhancing readability and overall aesthetics.

Use case 1: Adjust one or more directed graphs to improve the layout aspect ratio

Code:

unflatten path/to/input1.gv path/to/input2.gv ... > path/to/output.gv

Motivation:

In scenarios where multiple directed graph files exist, they often suffer from undesirably elongated layouts that make it difficult to visualize the relationships and hierarchies depicted. Using unflatten, you can process several input graph files at once, ensuring that each graph is adjusted for a more balanced layout aspect ratio, enhancing their readability and making them visually appealing.

Explanation:

• unflatten: The command invoked to adjust the graph’s layout, ensuring a more balanced aspect ratio.
• path/to/input1.gv path/to/input2.gv ...: These specify the locations of the input graph files that you want to adjust. You can list multiple input files, each separated by a space.
• >: This symbol is used to redirect the output of the command to a file.
• path/to/output.gv: The location where the processed graph is saved after being adjusted for a better layout aspect ratio.

Example Output:

After executing the command, the output file (output.gv) will showcase the directed graphs with improved layout ratios, making it easier to discern the graphs’ components compared to the original versions. Lines and nodes are better proportioned, contributing to a clearer visual hierarchy.

Use case 2: Use unflatten as a preprocessor for dot layout to improve aspect ratio

Code:

unflatten path/to/input.gv | dot -T png path/to/output.png

Motivation:

Before rendering a graph into a visual format using the dot tool, it’s beneficial to preprocess it with unflatten. This approach ensures that the layout is more visually balanced before image transformation, leading to a cleaner, more readable graphical output. It is particularly useful when an actual image format is needed, such as PNG, for presentations, reports, or web publications.

Explanation:

• unflatten: Coordinates the enhancement of the aspect ratio for the graph layout.
• path/to/input.gv: The file containing the original graph that needs preprocessing.
• |: This pipe symbol indicates that the output of the unflatten command will be used as the input for the next command, dot.
• dot -T png: This command reads the improved layout and converts it into a PNG image.
• path/to/output.png: The file path where the resulting image of the graph will be stored.

Example Output:

The output is a PNG image (output.png) with well-proportioned graph features. The nodes, edges, and connections appear lucid and easy to comprehend, making it suitable for any professional setting.

Use case 3: Display help

Code:

unflatten -?

Motivation:

Using the unflatten tool can sometimes require understanding a variety of options and arguments. By accessing the help documentation directly from the command line, users can quickly reference all available options, helping them maximize the utility of the command across different scenarios.

Explanation:

• unflatten: The tool invoked for adjusting graph layouts.
• -?: This option requests the display of a help message, which briefly explains the tool’s most crucial features, commands, and options.

Example Output:

The command outputs a succinct help message, listing all the available options and brief descriptions of what each one does. This facilitates users in correctly employing command features without needing to visit external resources.

Conclusion:

The unflatten command is an invaluable tool for those dealing with directed graph layouts. It provides essential preprocessing to improve readability and manageability of graphs. By following the examples above, users can effectively enhance their graph layouts, whether working with multiple files, preparing for visual conversions, or simply needing guidance on its utilities.