Plot Size Limits: Screen Size Vs. Specified Dimensions

Introduction

When creating plots in SLiM using slimgui.createPlot, users may encounter an issue where the specified dimensions (width and height) are not honored, particularly when the desired plot size exceeds the available screen real estate. This behavior, observed by Isabel, reveals that the plot window's size is constrained by the screen size, leading to discrepancies between the intended plot dimensions and the actual displayed dimensions. This article delves into the intricacies of this issue, exploring its implications, potential solutions, and best practices for creating plots with consistent dimensions across different display environments.

The Problem: Plot Size Constrained by Screen Size

Isabel's observation highlights a critical aspect of plot creation in SLiM. When a user specifies a large plot size, such as 2000x2000 pixels, the resulting plot window may not match these dimensions if the screen resolution or available screen space is insufficient. This behavior can lead to several undesirable outcomes:

• Distorted Aspect Ratios: If the plot window is constrained without preserving the aspect ratio, the resulting plot may appear stretched or compressed, distorting the visual representation of the data.
• Inconsistent Visualizations: Plots generated on different screens or with varying window configurations may exhibit different sizes and aspect ratios, making it challenging to compare visualizations consistently.
• User Experience Issues: Unexpected plot dimensions can confuse users and hinder their ability to interact with the plot effectively.

To illustrate this issue, consider the following SLiM code snippet:

initialize() { }
1 early() {
 plot = slimgui.createPlot("foo", c(0,1), c(0,1), width=2000, height=2000);
 plot.points(runif(1000), runif(1000), 16, size=0.4);
}

In this example, the user intends to create a plot with dimensions 2000x2000 pixels. However, if the screen resolution is lower than 2000x2000, or if the available window space is limited, the plot window will be constrained, potentially altering the aspect ratio and overall visual appearance. This is a significant concern because it compromises the integrity of the visualization and may lead to misinterpretations of the data.

Why This Happens

The underlying reason for this behavior lies in the way the operating system and graphics libraries handle window creation and resizing. When a program requests a window of a certain size, the operating system may impose constraints based on the screen resolution, available screen space, and window management policies. These constraints are in place to ensure that windows fit within the visible screen area and do not overlap excessively. However, in the context of scientific plotting, where precise control over dimensions is often crucial, these constraints can be problematic.

The Need for Consistent Plot Dimensions

In scientific research and data analysis, it is often essential to create plots with consistent dimensions and aspect ratios. This consistency is crucial for several reasons:

• Accurate Visual Comparisons: When comparing multiple plots, it is vital that they have the same dimensions and aspect ratios to ensure that visual differences reflect actual data variations rather than distortions caused by scaling or stretching.
• Reproducibility: Scientific results must be reproducible, and this includes the visualizations used to present data. Consistent plot dimensions help ensure that the same data generates the same visual representation across different environments.
• Publication Standards: Many scientific journals and publications have specific requirements for figure dimensions and aspect ratios. Adhering to these standards is essential for publication.

Potential Solutions and Best Practices

To address the issue of plot size constraints, several solutions and best practices can be employed.

1. Preserve Aspect Ratio

One crucial step is to ensure that the aspect ratio of the plot is preserved when the window is constrained. This prevents distortion and maintains the correct visual representation of the data. SLiM's plotting functionality should ideally provide an option to automatically preserve the aspect ratio when resizing or constraining plot windows. This ensures that the plot always appears in its intended proportions, regardless of the screen size or window dimensions.

2. Warn Users About Size Constraints

When the requested plot size exceeds the available screen space, SLiM could issue a warning to the user. This warning would inform the user that the plot window has been constrained and that the actual dimensions may differ from the specified dimensions. This proactive approach helps users understand why their plots may not appear as expected and allows them to adjust their settings accordingly.

3. Provide Options for Scaling and Zooming

In cases where the plot needs to be viewed in detail, SLiM could provide options for scaling and zooming the plot within the window. This would allow users to examine specific regions of the plot without changing the overall dimensions or aspect ratio. Scaling and zooming capabilities enhance the user's ability to explore the data visually and extract meaningful insights.

4. Implement Platform-Specific Handling

Different operating systems and graphics libraries may handle window creation and resizing in slightly different ways. To ensure consistent behavior across platforms, SLiM could implement platform-specific handling of plot size constraints. This would involve adapting the code to the specific requirements and limitations of each platform. Platform-specific handling ensures that the plot appearance is consistent across different operating systems, contributing to the reproducibility of results.

5. External Plotting Libraries

Consider using external plotting libraries like ggplot2 or matplotlib. These libraries offer more control over plot dimensions and rendering and can be integrated with SLiM to generate high-quality visualizations. These libraries often have sophisticated mechanisms for handling figure size and resolution, ensuring that plots are displayed correctly regardless of the screen size or output format.

6. Virtual Displays

For situations requiring large plots, consider using a virtual display. A virtual display is a software-created screen that can be larger than the physical display. This allows applications to create windows larger than the physical screen, which can be useful for generating high-resolution plots. Virtual displays provide a workaround for the screen size limitation, enabling the creation of plots with the desired dimensions.

7. Exporting Plots

Instead of relying solely on on-screen display, export plots to image files (e.g., PNG, PDF) at the desired resolution. This ensures that the plot is saved with the specified dimensions and can be viewed or printed without any size constraints. Exporting plots to image files guarantees that the plot's visual characteristics are preserved, making it a reliable method for sharing and archiving visualizations.

Conclusion

The issue of plot size constraints due to screen size limitations is a significant concern in scientific visualization. When the specified plot dimensions are not honored, it can lead to distorted aspect ratios, inconsistent visualizations, and user experience issues. To address this problem, it is crucial to preserve the aspect ratio when constraining plot windows, warn users about size limitations, provide options for scaling and zooming, implement platform-specific handling, and consider using external plotting libraries or virtual displays. By adopting these solutions and best practices, users can ensure that their plots are displayed accurately and consistently, regardless of the display environment. Ultimately, this enhances the integrity of the visualization and facilitates the accurate interpretation of data.

For more information on scientific plotting and visualization best practices, visit trusted resources such as the Data Visualization Society. This will help you improve your data storytelling skills and ensure your visualizations are both informative and visually appealing.