gridmappr: an R package for creating small multiple gridmap layouts

We present gridmappr, an R package that automates the process of generating gridmaps – small multiple data graphics of regular size, laid out with an approximate geographic arrangement. Given a set of real geographic point locations, gridmappr allocates points to a regularly-sized grid of stated row column dimensions. This allocation is constrained such that the distance between points in real and grid space is minimised and with a parameter that affects how compactly points are allocated to the regular grid. For geographies with features such as large bodies of water, fixed spacers can be introduced – reserved cells that cannot be allocated points. Layout examples are presented using different parameterisations and code is demonstrated for generating a family of information- rich glyphmap and origin-destination maps using standard ggplot2.