oplot

oplot is a term used in data visualization to describe an overlay plotting operation: drawing a new set of data on top of an existing axes without clearing what is already displayed. The name suggests layering additional plots onto a current figure, and it is used in several plotting environments, notably those with object-based graphics such as MATLAB- or Octave-like toolchains. In these contexts, oplot is described as a convenient way to add a series without issuing a full redraw of the plot.

In typical usage, oplot accepts coordinate arrays (x, y) and an optional style specification. It creates a new graphic object attached to the current axes and returns a handle to that object. The operation usually preserves the existing axis limits and previously drawn elements unless the API explicitly changes them. Overplotting is common in multi-series charts, dynamic simulations, or when progressively adding fit lines, reference curves, or error bands.

Key considerations when using oplot include managing color and line style to maintain readability, controlling the z-order of overlays, and keeping references to graphic handles for later updates or removal. Some environments implement overlay plotting as a specialized function named oplot, while others achieve the same effect by using a standard plotting call with a persistent or holding mode.

See also: plot, hold on, overlay, graphics handles, MATLAB plotting. The exact availability and syntax of oplot can vary between software packages, so users should consult the documentation for their specific environment to understand the supported arguments and behavior.