Construct grid from extent and scale — map

Take the two parameters defining the spatial grid of a map in GeoPressureR (extent and scale) and constructs various possible spatial variable of interest for the spatial grid (e.g., grid dimension, latitude and longitude...)

This functions is used in multiple functions of GeoPressureR to allow to only store extent and scale in tag and graph while having access to all spatial variables anywhere anytime.

Usage

map_expand(extent, scale)

Arguments

extent: geographical extent of the map on which the likelihood and graph model will be computed. Vector of length 4 c(xmin, xmax, ymin, ymax) or c(W, E, S, N).
scale: number of pixels per 1° latitude-longitude. For instance, scale = 10 for a resolution of 0.1° (~10km) and scale=4 for a resolution of 0.25° (~30km). To avoid interpolating the ERA5 data, the scale should be equal to or smaller than 10. Read more about scale on the Google earth Engine documentation .

Value

A list containing:

extent same as input
scale same as input
lat vector of latitude
lon vector of longitude
dim vector of length 2 of the dimension of the map (number of pixel in lat and lon)

Examples

str(map_expand(extent = c(0, 10, 0, 5), scale = 1))
#> List of 5
#>  $ extent: num [1:4] 0 10 0 5
#>  $ scale : num 1
#>  $ lat   : num [1:5] 4.5 3.5 2.5 1.5 0.5
#>  $ lon   : num [1:10] 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5
#>  $ dim   : num [1:2] 5 10

str(map_expand(extent = c(-16, 23, 0, 50), scale = 10))
#> List of 5
#>  $ extent: num [1:4] -16 23 0 50
#>  $ scale : num 10
#>  $ lat   : num [1:500] 50 49.8 49.8 49.7 49.5 ...
#>  $ lon   : num [1:390] -15.9 -15.9 -15.8 -15.6 -15.6 ...
#>  $ dim   : num [1:2] 500 390