The "keep charts clean" principle is a design principle for creating clear and easy-to-read charts and graphs. It involves minimizing clutter and unnecessary elements, such as gridlines and tick marks, and using a consistent style for all elements, such as labels and data points. The goal is to make the data and its message as clear as possible so that the viewer can easily understand the information being presented. Additionally, it is also important to use appropriate scales and axes, and to use colors and other visual cues judiciously, to help guide the viewer's attention to the most important information. Overall, the "keep charts clean" principle is about creating a simple, elegant, and easy-to-understand visual representation of data.

Here are some general principles that might be associated with keeping charts clean:

Simplicity: Keep the chart simple by including only the necessary information. Avoid clutter and unnecessary details that could confuse the audience.

Clarity: Ensure that the information presented in the chart is clear and easily understandable. Use clear labels, legends, and titles to guide the viewer.

Consistency: Maintain consistency in terms of color, style, and formatting across the chart. Consistency enhances readability and helps convey a unified message.

Avoid Chartjunk: Eliminate unnecessary decorations, embellishments, or excessive ornamentation. These elements, often referred to as "chartjunk," can distract from the main message.

Proper Scaling: Choose appropriate scales for the axes to accurately represent the data. Improper scaling can mislead the viewer and distort the interpretation of the information.

Use of White Space: Utilize white space strategically to separate different elements of the chart. White space helps reduce visual clutter and improves overall readability.

Choose Appropriate Chart Types: Select the right type of chart for the data you want to convey. Different data types and relationships are best represented using specific chart types (e.g., bar charts, line charts, pie charts).

Highlight Key Information: If there are specific data points or trends that you want to emphasize, use visual cues like color, annotations, or bold formatting to highlight them.

Remember that these principles may vary depending on the specific context and goals of your chart. The key is to make the information easily digestible for your audience while accurately representing the underlying data.