ggmapcn: China-Focused Mapping Tools with Optional Global Support for ggplot2

**ggmapcn** provides lightweight, ready-to-use tools for drawing China and world maps with *ggplot2*. It bundles clean geodata and offers simple, projection-aware helpers for basemaps, graticules, compasses, and scale bars.

Details

## Main Features

- **World maps**: `geom_world()` draws a complete global basemap with countries, coastlines, boundaries, and optional ocean fill.

- **China maps**: `geom_mapcn()` and `geom_boundary_cn()` provide provincial, prefecture-level maps and coastlines.

- **Annotation tools**: - `annotation_graticule()` — global graticules with projection-aware labels. - `annotation_scalebar()` — scale bar with automatic units and CRS detection. - `annotation_compass()` — north arrow with several styles.

- **Projection helper**: - `coord_proj()` — specify geographic `xlim`/`ylim` in degrees and automatically transform to any projection.

- **Geodata management**: - `check_geodata()` locates bundled world and China datasets and ensures graceful behaviour when data or internet resources are unavailable.

## Integration

All functions return standard *ggplot2* layers and work seamlessly with `sf` objects, custom projections, and `coord_sf()`.

See also

Useful links:

• https://rimagination.github.io/ggmapcn/

• Report bugs at https://github.com/Rimagination/ggmapcn/issues

Author

Maintainer: Liang Ren rl23@mails.tsinghua.edu.cn (ORCID)