Dashdot

Dashdot is a term used in graphics and data visualization to describe a line style that alternates between dash segments and dots. The pattern is often employed to distinguish lines in charts and diagrams when color alone is not sufficient, or when a secondary meaning needs to be conveyed.

In plotting libraries, dashdot is a predefined linestyle option. It provides a distinct, medium-contrast line without the heaviness of a solid line or the high density of a dotted line. The exact visual representation of a dashdot pattern can vary by library and rendering backend, so the appearance of dashdot lines may differ between software packages.

In vector graphics and web standards, dashdot can be produced by stroke dash patterns. For example, in SVG or CSS, a stroke-dasharray or equivalent setting can be configured to alternate longer dash segments with dots or small gaps. This allows designers to recreate the dashdot effect across different platforms while controlling the spacing and scale of the pattern.

Usage considerations include readability and printer fidelity. Dashdot lines may render differently on screens, in print, or under zoom, so it is common to accompany line patterns with appropriate legends or alternative indicators to ensure accessibility. Dashdot is one of several line styles used to convey information through non-axial cues.

See also: dashed line, dotted line, stroke-dasharray, line style, chart aesthetics.