Scott Chamberlain

Noam Ross

**randgeo** generates random points and shapes in GeoJSON and WKT
formats foruse in examples, teaching, or statistical applications.

Points and shapes are generated in the long/lat coordinate system and
withappropriate spherical geometry; random points are distributed evenly
acrossthe globe, and random shapes are sized according to a maximum
great-circledistance from the center of the shape.

**randgeo** was adapted from <https://github.com/tmcw/geojson-random> to
havea pure R implementation without any dependencies as well as
appropriategeometry. Data generated by **randgeo** may be processed or
displayed of withpackages such as
[**sf**](https://cran.r-project.org/package=sf),[**wicket**](https://cran.r-project.org/package=wicket),[**geojson**](https://cran.r-project.org/package=geojson),[**wellknown**](https://cran.r-project.org/package=wellknown),[**geojsonio**](https://cran.r-project.org/package=geojsonio),
or[**lawn**](https://cran.r-project.org/package=lawn).

Package API:

- `rg_position` - random position (lon, lat)
- `geo_point` - random GeoJSON point
- `geo_polygon` - random GeoJSON polygon
- `wkt_point` - random WKT point
- `wkt_polygon` - random WKT polygon

## Setup

Install `randgeo` - and we'll need a few other packages for examples
below.

::: {.highlight}
``` {.chroma tabindex="0"}
install.packages("randgeo")install.packages(c('leaflet', 'lawn'))
```
:::

::: {.highlight}
``` {.chroma tabindex="0"}
library(randgeo)
```
:::

Functions that start with `geo` are for creating GeoJSON data in JSON
format.If you want to create an R list or data.frame, you can use
`jsonlite::fromJSON`.

## Random

Evenly distributed across the sphere. The `bbox` option allowsyou to
limit points to within long/lat bounds.

::: {.highlight}
``` {.chroma tabindex="0"}
geo_point()#> $type#> [1] "FeatureCollection"#>#> $features#> $features[[1]]#> $features[[1]]$type#> [1] "Feature"#>#> $features[[1]]$geometry#> $features[[1]]$geometry$type#> [1] "Point"#>#> $features[[1]]$geometry$coordinates#> [1] 105.95999 -46.58477#>#>#> $features[[1]]$properties#> NULL#>#>#>#> attr(,"class")#> [1] "geo_list"
```
:::

Centered on a random point, with default maximum size

::: {.highlight}
``` {.chroma tabindex="0"}
geo_polygon()#> $type#> [1] "FeatureCollection"#>#> $features#> $features[[1]]#> $features[[1]]$type#> [1] "Feature"#>#> $features[[1]]$geometry#> $features[[1]]$geometry$type#> [1] "Polygon"#>#> $features[[1]]$geometry$coordinates#> $features[[1]]$geometry$coordinates[[1]]#> $features[[1]]$geometry$coordinates[[1]][[1]]#> [1] -138.49434 -25.11895#>#> $features[[1]]$geometry$coordinates[[1]][[2]]#> [1] -145.95566 -28.17623#>#> $features[[1]]$geometry$coordinates[[1]][[3]]#> [1] -145.87817 -28.74364#>#> $features[[1]]$geometry$coordinates[[1]][[4]]#> [1] -146.61325 -28.59748#>#> $features[[1]]$geometry$coordinates[[1]][[5]]#> [1] -139.18167 -31.07703#>#> $features[[1]]$geometry$coordinates[[1]][[6]]#> [1] -140.88748 -31.24708#>#> $features[[1]]$geometry$coordinates[[1]][[7]]#> [1] -143.50402 -33.93551#>#> $features[[1]]$geometry$coordinates[[1]][[8]]#> [1] -146.48114 -30.43185#>#> $features[[1]]$geometry$coordinates[[1]][[9]]#> [1] -144.68315 -35.45465#>#> $features[[1]]$geometry$coordinates[[1]][[10]]#> [1] -157.58084 -24.52897#>#> $features[[1]]$geometry$coordinates[[1]][[11]]#> [1] -138.49434 -25.11895#>#>#>#>#> $features[[1]]$properties#> NULL#>#>#>#> attr(,"class")#> [1] "geo_list"
```
:::

Visualize your shapes with **lawn**.

::: {.highlight}
``` {.chroma tabindex="0"}
lawn::view(jsonlite::toJSON(unclass(geo_polygon(count = 4)), auto_unbox = TRUE))
```
:::

<figure class="center">
<img src="/img/blog-images/2017-04-20-randgeo/plot1.png" width="300"
alt="visualize shapes with the lawn package for R" />
<figcaption>Shapes visualized in R with lawn</figcaption>
</figure>

## WKT

Functions prefixed with `wkt` create random Well-Known Text (WKT) data.
These functionswrap the GeoJSON versions, but then convert the data to
WKT.

Random point:

::: {.highlight}
``` {.chroma tabindex="0"}
wkt_point()#> [1] "POINT (179.8795330 -29.1106238)"
```
:::

Random polygon:

::: {.highlight}
``` {.chroma tabindex="0"}
wkt_polygon()#> [1] "POLYGON ((-60.0870329 -12.9315478, -61.5073816 -25.3204334, -62.6987366 -24.5766272, -64.1853669 -24.0497260, -67.7152546 -27.4752321, -68.4190340 -26.9510818, -67.6018452 -21.5489551, -64.3083560 -21.6772242, -63.1471630 -21.9415438, -64.1137279 -14.2398013, -60.0870329 -12.9315478))"
```
:::

## Use case

Example of geospatial data manipulation, using `randgeo`, `leaflet`
and`lawn`.

Steps:

- Generate random overlapping polygons
- Calculate a single polygon from overlapping polygons
- Map polygon
- Generate random locaitons (points)
- Clip locations to the polygon
- Overlay locations (more random points) on the polygon

::: {.highlight}
``` {.chroma tabindex="0"}
library(randgeo)library(lawn)library(leaflet)
```
:::

generate random data

::: {.highlight}
``` {.chroma tabindex="0"}
set.seed(5)polys <- randgeo::geo_polygon(count = 2, num_vertices = 4, bbox = c(-120, 40, -100, 50))
```
:::

Get intersection of polygons

::: {.highlight}
``` {.chroma tabindex="0"}
polysinter <- lawn::lawn_intersect(polys$features[[1]], polys$features[[2]])
```
:::

Map polygons

::: {.highlight}
``` {.chroma tabindex="0"}
polysinter %>% lawn::view()
```
:::

<figure class="center">
<img src="/img/blog-images/2017-04-20-randgeo/plot2.png" width="300"
alt="visualize shapes with the lawn package for R" />
<figcaption>Shapes visualized in R with lawn</figcaption>
</figure>

Generate random points - clip points to polygon

::: {.highlight}
``` {.chroma tabindex="0"}
pts <- randgeo::geo_point(count = 500, bbox = c(-120, 40, -100, 50))pts <- lawn::lawn_within( points = lawn_featurecollection(pts), polygons = lawn_featurecollection(polysinter))
```
:::

Draw polygon + points on map

::: {.highlight}
``` {.chroma tabindex="0"}
polysinter %>% view() %>% addGeoJSON(geojson = jsonlite::toJSON(unclass(pts)))
```
:::

<figure class="center">
<img src="/img/blog-images/2017-04-20-randgeo/plot3.png" width="300"
alt="visualize shapes with the lawn package for R" />
<figcaption>Shapes visualized in R with lawn</figcaption>
</figure>

## Feedback

Let us know what you think! `randgeo` doesn't have any revdep's on CRAN
yet, butis being [used in one package on
GitHub](https://github.com/search?utf8=%E2%9C%93&q=%22randgeo%22+language%3AR+-user%3Acran+-user%3Aropensci&type=Code).

randgeo

generates random points and shapes in GeoJSON and WKT formats foruse in examples, teaching, or statistical applications. Points and shapes are generated in the long/lat coordinate system and withappropriate spherical geometry; random points are distributed evenly acrossthe globe, and random shapes are sized according to a maximum great-circledistance from the center of the shape.

Rogue Scholar Beiträge

Random GeoJSON and WKT with randgeo