---
title: "FAQ"
description: "Short answers about boundary data, inset behavior, and adding your own data."
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{FAQ}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(collapse = TRUE, comment = "#>")
```

## Why move Okinawa and Ogasawara?

Japan spans a long north-south and east-west range. A geographically literal
map can make smaller islands difficult to see. `jpmap` follows the `usmap`
idea of using insets so important regions remain visible in ordinary plots.
Use `inset = FALSE`, `inset = "okinawa"`, or `inset = "ogasawara"` when you
want to exclude one or both transported island groups. You can also use
`okinawa = FALSE` or `ogasawara = FALSE`, mirroring the style of
`UchidaMizuki/jpmap`. `plot_jpmap()` draws inset boxes by default; set
`inset_boxes = FALSE` to remove them. The boxes are visual guide frames for
the transported inset clusters and are sized to cover the Okinawa and
Ogasawara source extents that `jpmap` transports. They are display frames, not
legal extents. When boxes are shown, the longitude/latitude lines inside them
are local graticules for the transported island group, so they show true island
coordinates rather than the destination coordinates of the box.

## Does jpmap include boundary data?

Large boundary GeoPackages live outside the functionality package. Install the
companion `jpmapdata` package when you want ready-to-use boundary files, or use
`jpmap_build_data()` to build a local GeoPackage from MLIT N03 administrative
area data. Use `jpmap_build_data(prefecture = "Ehime")` when you only need one
prefecture.

## Which boundary levels are supported?

The API supports `regions = "prefectures"` and
`regions = "municipalities"`.

## Can I add my own points or lines?

Yes. Use `jpmap_transform()` on a data frame, `sf` object, or `sfc` geometry
vector, then add it to a `plot_jpmap()` map with `ggplot2` layers.