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

Gnuplot is a powerful graph plotting tool that can output in multiple formats. It can be used interactively or by executing command scripts to plot graphs. In this article, we will explore different use cases of the gnuplot command.

Use case 1: Start the interactive graph plotting shell

Code:

gnuplot

Motivation: Starting the interactive graph plotting shell allows users to quickly create and customize graphs by using gnuplot commands. This is useful when you need to visually explore and experiment with different graph parameters.

Explanation:

• gnuplot: This command starts the interactive gnuplot shell.

Example output: The gnuplot shell opens, and you can start entering commands to plot and customize graphs.

Use case 2: Plot the graph for the specified graph definition file

Code:

gnuplot path/to/definition.plt

Motivation: When you have a predefined graph definition file, using gnuplot to directly plot the graph saves time and makes the process more automated. This can be useful when you have a large number of graph definition files or when you want to plot graphs in a batch processing scenario.

Explanation:

• gnuplot: This command starts gnuplot.
• path/to/definition.plt: Specifies the path to the graph definition file to be plotted.

Example output: The graph defined in the definition.plt file is plotted and displayed.

Use case 3: Set the output format by executing a command before loading the definition file

Code:

gnuplot -e "set output 'path/to/filename.png' size 1024,768" path/to/definition.plt

Motivation: Customizing the output format is essential when you want to save the plotted graph in a specific format or adjust the size of the output. This use case is particularly useful when you are automating the graph plotting process and need flexibility in choosing the output format.

Explanation:

• gnuplot: This command starts gnuplot.
• -e "set output 'path/to/filename.png' size 1024,768": Executes the command set output 'path/to/filename.png' size 1024,768 before loading the graph definition file. This command sets the output format to PNG and specifies the size of the output as 1024x768 pixels.
• path/to/definition.plt: Specifies the path to the graph definition file to be plotted.

Example output: The graph defined in the definition.plt file is plotted, and the output is saved as a PNG file with the specified size.

Use case 4: Persist the graph plot preview window after gnuplot exits

Code:

gnuplot --persist path/to/definition.plt

Motivation: By default, the graph plot preview window closes immediately after gnuplot exits. However, in some scenarios, it is useful to keep the plot window open to analyze or further interact with the graph. This use case allows you to persist the graph preview window even after gnuplot exits.

Explanation:

• gnuplot: This command starts gnuplot.
• --persist: This flag instructs gnuplot to persist the graph plot preview window after gnuplot exits.
• path/to/definition.plt: Specifies the path to the graph definition file to be plotted.

Example output: The graph defined in the definition.plt file is plotted, and the plot preview window remains open after gnuplot exits.

Conclusion:

Gnuplot provides a versatile and powerful way to plot graphs. Whether through the interactive shell or by executing command scripts, gnuplot enables users to create visually appealing graphs for various applications. By understanding these different use cases of the gnuplot command, you can unlock the full potential of this graph plotting tool.