| Title: | Turn Geospatial Polygons into Regular or Hexagonal Grids |
| Version: | 0.1.2 |
| Description: | Turn irregular polygons (such as geographical regions) into regular or hexagonal grids. This package enables the generation of regular (square) and hexagonal grids through the package 'sp' and then assigns the content of the existing polygons to the new grid using the Hungarian algorithm, Kuhn (1955) (<doi:10.1007/978-3-540-68279-0_2>). This prevents the need for manual generation of hexagonal grids or regular grids that are supposed to reflect existing geography. |
| Imports: | methods, sp, sf, Rcpp |
| License: | MIT + file LICENSE |
| Encoding: | UTF-8 |
| LinkingTo: | Rcpp, RcppArmadillo |
| Suggests: | testthat, lintr, covr |
| RoxygenNote: | 7.2.3 |
| URL: | https://github.com/jbaileyh/geogrid |
| BugReports: | https://github.com/jbaileyh/geogrid/issues |
| NeedsCompilation: | yes |
| Packaged: | 2023-08-15 21:18:48 UTC; rhafen |
| Author: | Joseph Bailey [aut, cph],
Ryan Hafen  [ctb,
cre],
Jakub Nowosad
[ctb],
Lars Simon Zehnder [ctb] (RcppArmadillo implmentation of Munkres'
Assignment Algorithm) |
| Maintainer: | Ryan Hafen <rhafen@gmail.com> |
| Repository: | CRAN |
| Date/Publication: | 2023-08-19 04:52:36 UTC |
geogrid: Turn Geospatial Polygons into Regular or Hexagonal Grids
Description
Turn irregular polygons (such as geographical regions) into regular or hexagonal grids. This package enables the generation of regular (square) and hexagonal grids through the package 'sp' and then assigns the content of the existing polygons to the new grid using the Hungarian algorithm, Kuhn (1955) (doi:10.1007/978-3-540-68279-0_2). This prevents the need for manual generation of hexagonal grids or regular grids that are supposed to reflect existing geography.
Author(s)
Maintainer: Ryan Hafen rhafen@gmail.com (ORCID) [contributor]
Authors:
Joseph Bailey jbailey@futurecities.catapult.org.uk [copyright holder]
Other contributors:
Jakub Nowosad nowosad.jakub@gmail.com (ORCID) [contributor]
Lars Simon Zehnder (RcppArmadillo implmentation of Munkres' Assignment Algorithm) [contributor]
See Also
Useful links:
Assign the polygons in the original spatial data to their new location.
Description
Assigns each polygon in the original file to a new location in the gridded geometry using the Hungarian algorithm.
Usage
assign_polygons(shape, new_polygons)
## S3 method for class 'SpatialPolygonsDataFrame'
assign_polygons(shape, new_polygons)
## S3 method for class 'sf'
assign_polygons(shape, new_polygons)
Arguments
shape |
A "SpatialPolygonsDataFrame" or an sf object representing the original spatial polygons. |
new_polygons |
A "geogrid" object returned from
|
Value
An object of the same class as shape
Examples
library(sf)
input_file <- system.file("extdata", "london_LA.json", package = "geogrid")
original_shapes <- st_read(input_file) %>% st_set_crs(27700)
# calculate grid
new_cells <- calculate_grid(shape = original_shapes,
grid_type = "hexagonal", seed = 1)
grid_shapes <- assign_polygons(original_shapes, new_cells)
plot(grid_shapes)
par(mfrow = c(1, 2))
plot(st_geometry(original_shapes))
plot(st_geometry(grid_shapes))
## Not run:
# look at different grids using different seeds
par(mfrow=c(2, 3), mar = c(0, 0, 2, 0))
for (i in 1:6) {
new_cells <- calculate_grid(shape = original_shapes,
grid_type = "hexagonal", seed = i)
plot(new_cells, main = paste("Seed", i, sep=" "))
}
## End(Not run)
Calculate size of grid items (deprecated).
Description
Given an input multipolgyon spatial data frame this function calculates the required cell size of a regular or hexagonal grid.
Usage
calculate_cell_size(
shape,
shape_details = NULL,
learning_rate = 0.03,
grid_type = c("hexagonal", "regular"),
seed = NULL,
verbose = FALSE
)
Arguments
shape |
A 'SpatialPolygonsDataFrame' object representing the original spatial polygons. |
shape_details |
deprecated. |
learning_rate |
The rate at which the gradient descent finds the optimum cellsize to ensure that your gridded points fit within the outer boundary of the input polygons. |
grid_type |
Either 'hexagonal' for a hexagonal grid (default) or 'regular' for a regular grid. |
seed |
An optional random seed integer to be used for the grid calculation algorithm. |
verbose |
A logical indicating whether messages should be printed as the algorithm iterates. |
Calculate grid from spatial polygons.
Description
Given an input multipolgyon spatial data frame this function calculates a hexagonal or regular grid that strives to preserve the original geography.
Usage
calculate_grid(
shape,
learning_rate = 0.03,
grid_type = c("hexagonal", "regular"),
seed = NULL,
verbose = FALSE
)
## S3 method for class 'SpatialPolygonsDataFrame'
calculate_grid(
shape,
learning_rate = 0.03,
grid_type = c("hexagonal", "regular"),
seed = NULL,
verbose = FALSE
)
## S3 method for class 'sf'
calculate_grid(
shape,
learning_rate = 0.03,
grid_type = c("hexagonal", "regular"),
seed = NULL,
verbose = FALSE
)
Arguments
shape |
A 'SpatialPolygonsDataFrame' or an sf object representing the original spatial polygons. |
learning_rate |
The rate at which the gradient descent finds the optimum cellsize to ensure that your gridded points fit within the outer boundary of the input polygons. |
grid_type |
Either 'hexagonal' for a hexagonal grid (default) or 'regular' for a regular grid. |
seed |
An optional random seed integer to be used for the grid calculation algorithm. |
verbose |
A logical indicating whether messages should be printed as the algorithm iterates. |
Examples
library(sf)
input_file <- system.file('extdata', 'london_LA.json', package = 'geogrid')
original_shapes <- st_read(input_file) %>% st_set_crs(27700)
# calculate grid
new_cells <- calculate_grid(shape = original_shapes,
grid_type = 'hexagonal', seed = 1)
grid_shapes <- assign_polygons(original_shapes, new_cells)
plot(grid_shapes)
par(mfrow = c(1, 2))
plot(st_geometry(original_shapes))
plot(st_geometry(grid_shapes))
## Not run:
# look at different grids using different seeds
par(mfrow=c(2, 3), mar = c(0, 0, 2, 0))
for (i in 1:6) {
new_cells <- calculate_grid(shape = original_shapes,
grid_type = 'hexagonal', seed = i)
plot(new_cells, main = paste('Seed', i, sep=' '))
}
## End(Not run)
Extract details from provided polygons (deprecated).
Description
Extract spatial extent, range and other geospatial features from the output
of read_polygons. Items are returned as a list for use in
calculate_grid.
Usage
get_shape_details(input_shape)
Arguments
input_shape |
A "SpatialPolygonsDataFrame" object representing the original spatial polygons. |
Extract details from provided polygons.
Description
Extract spatial extent, range and other geospatial features from the output
of read_polygons. Items are returned as a list for use in
calculate_grid.
Usage
get_shape_details_internal(input_shape)
Arguments
input_shape |
A "SpatialPolygonsDataFrame" object representing the original spatial polygons. |
hungarian_cc
Description
hungarian_cc
Usage
hungarian_cc(cost)
Arguments
cost |
cost matrix |
hungariansafe_cc
Description
hungariansafe_cc
Usage
hungariansafe_cc(cost)
Arguments
cost |
cost matrix |
Plot a 'geogrid' object
Description
Plot a 'geogrid' object
Usage
## S3 method for class 'geogrid'
plot(x, y, ...)
Arguments
x |
An object of class 'geogrid' to plot. |
y |
ignored |
... |
Additional parameters passed to the 'sp' package's plot method. |
Import spatial data.
Description
Simple function to read spatial data into a SpatialPolygonsDataFrame. Based on st_read from package sf.
Usage
read_polygons(file)
Arguments
file |
A file path pointing to a shapefile or GeoJSON file, or a
character string holding GeoJSON data. See the |