MetaPlot is a set of Metapost macros for manipulating pre-
generated plots (and similar objects), and formatting them for
inclusion in a Metapost figure. The intent is that the plots
can be generated by some outside program, in an abstract manner
that does not require making decisions about on-page sizing and
layout, and then they can be imported into MetaPlot and
arranged using the full capabilities of Metapost. Metaplot also
includes a very flexible set of macros for generating plot
axes, which may be useful in other contexts as well. Presently,
MetaPlot is in something of a pre-release beta state; it is
quite functional, but the syntax of the commands is still
potentially in flux.

Homepage:
https://ctan.org/pkg/metaplot
