R6 Class to Select an Area of Interest (AOI) from a Global Grid

Source: R/shiny_app.R

The 'select_aoi_global_grid' class allows the user to select an Area of Interest (AOI) (see the examples section for all available options)

# init <- select_aoi_global_grid$new()

References

https://github.com/r-spatial/mapedit/blob/master/experiments/gadget_draw2.R

Public fields

area_of_interest

an R object (character string, vector)

leaflet_provider_base

a leaflet provider object

leaflet_provider_secondary

a leaflet provider object

crs_value

a numeric value

use_s2

a boolean

verbose

a boolean

Methods

Public methods

Method new()

Initialization method for the 'select_aoi_global_grid' R6 class

Usage

select_aoi_global_grid$new(
  area_of_interest = NULL,
  leaflet_provider_base = leaflet::providers$CartoDB.Positron,
  leaflet_provider_secondary = leaflet::providers$Esri.WorldImagery,
  crs_value = 4326,
  use_s2 = FALSE,
  verbose = FALSE
)

Arguments

area_of_interest

either NULL (which allows the user to draw the area of interest on the map) or a character string (i.e. a 'country' or a 'continent') or a named bounding box vector (such as c(xmin = 16.1, xmax = 16.6, ymax = 48.6, ymin = 47.9)). The 'countries' and 'continents' can be extracted from the "rnaturalearth::ne_countries(scale = 110, type = 'countries', returnclass = 'sf')" function and specifically the columns: 'sovereignt' and 'continent'

leaflet_provider_base

a leaflet provider object

leaflet_provider_secondary

a leaflet provider object

crs_value

a value. The coordinate reference system. The default value of the crs is 4326

use_s2

a boolean. If TRUE, use the s2 spherical geometry package for geographical coordinate operations (see the documentation of the 'sf::sf_use_s2()' function for more information)

verbose

a boolean. If TRUE then information will be printed in the console

Method draw_edit_internal()

Internal Shiny application to visualize the selected area

Usage

select_aoi_global_grid$draw_edit_internal(lft_map)

Arguments

lft_map

a leaflet map

Method draw_edit_aoi()

Allows to view the Global Grid on the map including a popup that shows the Area of each grid rectangle (or hexagon). The user can then select an Area of Interest (AOI)

Usage

select_aoi_global_grid$draw_edit_aoi(degrees = 1, square_geoms = TRUE)

Arguments

degrees

a numeric value. This can be either 1.0 or 5.0 to allow queries to the 'OpenAltimetry' API

square_geoms

a boolean. If FALSE then a hexagonal grid will be created

Method selected_areas_global_grid()

Takes the selected Area(s) of Interest (AOI) from the draw_edit_aoi() method and returns a simple features object with the corresponding n-degree grid cells

Usage

select_aoi_global_grid$selected_areas_global_grid(plot_data = FALSE)

Arguments

plot_data

a boolean specifying if the selected from the user AOI's and the corresponding grid cells should be plotted side by side. If FALSE then only the simple features object will be returned. If TRUE and the initial 'area_of_interest' parameter is NULL then a single plot will be displayed.

Returns

either an 'sfc' object (if the initial 'area_of_interest' parameter is NULL) or an 'sf' object consisting of the n-degree grid cells

Method selected_aoi_sf()

Returns the selected area of interest (AOI) by the user in form of an 'sfc' object

Usage

select_aoi_global_grid$selected_aoi_sf()

Returns

an 'sfc' object

Method clone()

The objects of this class are cloneable with this method.

Usage

select_aoi_global_grid$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples


if (FALSE) {

require(IceSat2R)
require(magrittr)

#........................................
# 1st. Option: Select an AOI from the map
#........................................

init = select_aoi_global_grid$new(area_of_interest = NULL,
                                  verbose = TRUE)
init$draw_edit_aoi()
sf_obj = init$selected_areas_global_grid(plot_data = TRUE)
sf_obj


#...............................................
# observe the available countries and continents
# using the 'rnaturalearth' R package
#...............................................

cntr_cnt = rnaturalearth::ne_countries(scale = 110,
                                       type = 'countries',
                                       returnclass = 'sf')

cntr_cnt = cntr_cnt[, c('sovereignt', 'continent')]

# sort(cntr_cnt$sovereignt)
# sort(unique(cntr_cnt$continent))


#.......................................
# 2nd. Option: Select a 'country' as AOI   (5-degrees query)
#.......................................

init = select_aoi_global_grid$new(area_of_interest = 'Antarctica',
                                  verbose = TRUE)

init$draw_edit_aoi(degrees = 5.0, square_geoms = TRUE)
sf_obj = init$selected_areas_global_grid(plot_data = TRUE)
sf_obj


#.........................................
# 3rd. Option: Select a 'continent' as AOI   (1-degree query)
#.........................................

init = select_aoi_global_grid$new(area_of_interest = 'North America',
                                  verbose = TRUE)

init$draw_edit_aoi(degrees = 1.0, square_geoms = TRUE)
sf_obj = init$selected_areas_global_grid(plot_data = TRUE)
sf_obj


#.........................................
# 4th. Option: Use a bounding box as input  ('Greenland Ice Sheet')
#.........................................

data(ne_10m_glaciated_areas)

dat_bbx = ne_10m_glaciated_areas %>%
  subset(!is.na(name)) %>%
  subset(name == "Greenland Ice Sheet") %>%
  sf::st_bbox(crs = 4326)

dat_bbx

init = select_aoi_global_grid$new(area_of_interest = dat_bbx,
                                  verbose = TRUE)

init$draw_edit_aoi(degrees = 1.0, square_geoms = TRUE)
sf_obj = init$selected_areas_global_grid(plot_data = TRUE)
sf_obj


#......................................................
# 5th. Option: Create a global hexagonal 5-degrees grid
#......................................................

bbx_global = c(xmin = -180, xmax = 180, ymin = -90, ymax = 90)

init = select_aoi_global_grid$new(area_of_interest = bbx_global,
                                  verbose = TRUE)

init$draw_edit_aoi(degrees = 5.0, square_geoms = FALSE)
sf_obj = init$selected_areas_global_grid(plot_data = TRUE)
sf_obj

}