Type: Package
Title: Miscellaneous Spatial Functions
Date: 2022-02-14
Version: 0.1.2
Description: Contains convenience functions for working with spatial data across multiple UTM zones, raster-vector operations common in the analysis of conflict data, and converting degrees, minutes, and seconds latitude and longitude coordinates to decimal degrees.
Depends: R (≥ 3.4.0)
Imports: sf, sp, raster, units
Suggests: ggplot2, geosphere, lwgeom, microbenchmark, knitr, rmarkdown, testthat (≥ 2.1.0), covr
License: GPL (≥ 3)
Encoding: UTF-8
URL: https://github.com/jayrobwilliams/RWmisc
BugReports: https://github.com/jayrobwilliams/RWmisc/issues
VignetteBuilder: knitr
RoxygenNote: 7.1.1
NeedsCompilation: no
Packaged: 2022-02-14 18:59:36 UTC; rob
Author: Rob Williams ORCID iD [aut, cre]
Maintainer: Rob Williams <jayrobwilliams@gmail.com>
Repository: CRAN
Date/Publication: 2022-02-14 19:30:02 UTC

RWmisc: Miscellaneous Spatial Functions

Description

Contains convenience functions for working with spatial data across multiple UTM zones, raster-vector operations common in the analysis of conflict data, and converting degrees, minutes, and seconds latitude and longitude coordinates to decimal degrees.

Details

Convenience functions for working with spatial data.

Author(s)

Maintainer: Rob Williams jayrobwilliams@gmail.com (ORCID)

See Also

Useful links:

UTM Convenience Functions

Description

Functions for converting latitude-longitude data to UTM.

Usage

long2UTM(long)

UTMzones(long)

chooseUTM(long)

Arguments

long

A vector of longitude values.

Value

UTM vector of zone numbers.

UTM vector of zone numbers.

UTM zone number.

Examples

long2UTM(c(-90, 0, 90))
UTMzones(c(-90, 90, 90))
chooseUTM(c(-90, -80, -70))

Convert from degrees, minutes, and seconds to decimal degrees

Description

Convert latitudes and longitudes from degrees, minutes, and seconds to decimal degrees for conversion to spatial objects.

Usage

dms2dd(lon, lat)

Arguments

lon

a character vector of longitude coordinates in degrees, minutes, and seconds; see details

lat

a character vector of latitude coordinates in degrees, minutes, and seconds; see details

Details

lon and lat are expected to be in the format ⁠"degrees° minutes' seconds" (direction)"⁠ where direction is optional. If direction is not present, dms2dd will use negative signs (-) to determine positioning of coordinates.

Value

An n * 2 matrix where n is the length of lon and lat.

Examples

ll <- data.frame(lon = c("-122° 19' 55\"",
                         "71° 3' 32\" W"),
                 lat = c("47° 36' 22\"",
                         "42° 21' 36\" N"),
                 stringsAsFactors = FALSE)
dms2dd(ll[, 'lon'], ll[, 'lat'])

Extract layers by country from GADM GeoPackage file

Description

Extract one or more levels of administrative unit geometries from the GADM database in GeoPackage format

Usage

gadm.extract(input, output, countries = NULL, level = 0:5, ...)

Arguments

input

GeoPackage file to read from

output

name of file to save output to

countries

country or countries to limit results to, if NULL returns all countries

level

level(s) of administrative units 0:5 to extract; note not all levels are defined for all countries

...

additional arguments passed to sf::st_write()

Details

This function is designed to extract subsets of the Database of Global Administrative Areas (GADM). It uses the version of the database in GeoPackage format that provides one layer for each level of administrative division, available at https://gadm.org/download_world.html. The current version of this file is gadm36_levels.gpkg. It is intended for programmatic and reproducible subsetting of the database without requiring the user to individually download specific country data files.

Examples

## Not run: 
## extract
gadm.extract("gadm36_levels.gpkg", "Nordics.gpkg",
             c("Denmark", "Finland", "Iceland", "Norway", "Sweden"),
             level = 0:2)

## add layers 3 and 4, use delete_layer = TRUE to rewrite existing layers
gadm.extract("gadm36_levels.gpkg", "Nordics.gpkg",
             c("Denmark", "Finland", "Iceland", "Norway", "Sweden"),
             level = 0:4, delete_layer = TRUE)

## End(Not run)

Weight Raster Cells by Overlapping Polygons

Description

Weight raster cells by overlapping polygons to avoid over-counting when aggregating by polygons

Usage

overlap.weight(raster, polygons, count = FALSE, warn = TRUE)

Arguments

raster

a RasterLayer object.

polygons

a SpatialPolygons, SpatialPolygonsDataFrame, or simple feature collection with at least two features. The function will still work with only one polygon, but values will be unchanged, and the result will be equivalent to mask(raster, polygons).

count

a logical indicating whether to return a raster with the count of polygons intersecting each cell, or a raster with original values weighted by 1/number of intersecting polygons.

warn

include warnings? Most common is that the returned raster will be an intersection of the raster and the polygons. Default TRUE.

Details

This function takes a raster and a set of polygons as arguments. It counts the number of polygons that intersect each raster cell. It can return either a raster with the count of the number of intersecting polygons as cell values or the original raster with cell values weighted by 1 / the number of intersecting polygons (the default behavior). Cells that do not intersect any polygons will receive a value of NA. If the extent of the polygons is less than the extent of the raster, then the function will warn that it is cropping the raster to the polygons' extent.

Value

a RasterLayer object.

Examples

library(sf)
library(raster)
polys_t <- st_sfc(list(st_polygon(list(rbind(c(2,2), c(2,6),
                                             c(6,6), c(6,2),
                                             c(2, 2)))),
                       st_polygon(list(rbind(c(8,8), c(4,8),
                                             c(4,4), c(8,4),
                                             c(8,8))))),
                  crs = st_crs('OGC:CRS84'))
raster_t <- raster(nrows = 10, ncols = 10, xmn = 0,
                   xmx = 10, ymn = 0, ymx = 10,
                   vals = 1:100,
                   crs = CRS(st_crs(polys_t)$proj4string))
overlap.weight(raster_t, polys_t)

Point-Polygon Distances

Description

Calculate the maximum or minimum possible distance from a point to the edge of a given polygon.

Usage

point.poly.dist(point, poly, max = TRUE, by_element = FALSE)

Arguments

point

A simplefeatures object of class point.

poly

A simplefeatures object of class polygon or multipolygon.

max

Logical; return maximum or minimum distance? default TRUE

by_element

Logical; return total maximum or minimum, or for each input point? default FALSE

Value

Maximum or minimum distance between a point and a polygon.

Examples

library(sf)
polys <- st_sfc(st_polygon(list(rbind(c(0,0), c(0,1), c(1,1), c(1,0), c(0,0)))),
crs = st_crs('OGC:CRS84'))
points <- st_sfc(st_multipoint(rbind(c(.25, .5), c(.75, .5), c(.5, .5))),
                 crs = st_crs('OGC:CRS84'))
point.poly.dist(points, polys)

Project to UTM

Description

Project an object in latitude/longitude to UTM.

Usage

projectUTM(x)

## S3 method for class 'sf'
projectUTM(x)

## S3 method for class 'sfc'
projectUTM(x)

## S3 method for class 'SpatialPointsDataFrame'
projectUTM(x)

## S3 method for class 'SpatialPoints'
projectUTM(x)

## S3 method for class 'SpatialPolygonsDataFrame'
projectUTM(x)

## S3 method for class 'SpatialPolygons'
projectUTM(x)

Arguments

x

An sf or sp object in latitude-longitude CRS.

Value

An sf or sp object projected to UTM CRS.

Examples

library(sf)
nc <- st_read(system.file("shape/nc.shp", package="sf"))
st_crs(projectUTM(nc))

Blank Theme

Description

A ggplot theme with no grid elements or gray background.

Usage

theme_rw()

Value

A ggplot theme object.

Examples

ggplot2::ggplot(mtcars, ggplot2::aes(x = hp, y = mpg)) +
ggplot2::geom_point() +
theme_rw()