---
title: "Maps of Ulaanbaatar"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Maps of Ulaanbaatar}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.width = 7,
  fig.height = 5,
  # Sharp figures on the website; small ones in the CRAN package.
  dpi = if (identical(Sys.getenv("IN_PKGDOWN"), "true")) 200 else 96,
  eval = rlang::is_installed("ggplot2")
)
```

```{r setup}
library(mongolmaps)
```

Ulaanbaatar has three map levels: the city, its 9 districts (duureg) and
its 204 khoroos. The layers fit together exactly.

```{r levels}
mn_ub()
mn_ub_districts()
mn_khoroos()
```

## Districts

```{r districts}
mn_map(mn_ub_districts(), fill = name, label = TRUE)
```

Baganuur and Bagakhangai are exclaves, far to the east and south-east of the
main city. To focus on the city centre, keep the districts you need:

```{r central}
central <- c("Bayangol", "Bayanzurkh", "Chingeltei", "Khan-Uul", "Songinokhairkhan", "Sukhbaatar")
mn_map(mn_khoroos(district = central), fill = parent_pcode)
```

District names accept common abbreviations such as `"BZD"`, `"SBD"` or
`"KhUD"`, and Cyrillic:

```{r abbrev}
mn_khoroos(district = "\u0411\u0417\u0414")
```

## Khoroos

Khoroos are numbered within their district; the number is in the `number`
column, and `mn_map(label = TRUE)` shows it.

```{r khoroos}
mn_map(mn_khoroos(district = "Sukhbaatar"), fill = area_km2, label = TRUE)
```

To find one khoroo, use `mn_match()` with the district:

```{r match}
mn_match("15-r khoroo", level = "bag", within = "Bayangol")
mn_match("Bayangol 15")
```

## Joining statistics

NSO publishes many statistics by khoroo. The example data has the mid-year
population:

```{r join, fig.height = 5.5}
pop <- mn_example_population[mn_example_population$Year == 2025, ]
khoroo_pop <- mn_join(pop, by = "Region", level = "bag", within = "Ulaanbaatar")

mn_map(
  khoroo_pop[khoroo_pop$parent_pcode %in% c("MN1107", "MN1119", "MN1125"), ],
  fill = value / area_km2,
  title = "People per km2: Bayangol, Sukhbaatar and Chingeltei"
)
```

## Interactive maps

```{r leaflet, eval = FALSE}
mn_leaflet(khoroo_pop, fill = value)
```

## About the khoroo boundaries

The khoroo boundaries come from the open khoroo-map project, which does not
state where its data come from, so treat them as **unofficial**. They were
fitted to the official Ulaanbaatar outline; the district boundaries in
`mn_ub_districts()` are the unions of their khoroos and follow the current
city layout. See `?mn_khoroos` for details.