A small example grid

A 12 by 9 grid of square cells in the Gulf of Maine, carrying one column of each kind of quantity this package draws. Used by the examples and the tests, so that neither needs a fitted model, a covariate product or the network.

Usage

example_grid(seed = 42)

Arguments

seed

The random seed. Fixed by default, so the examples draw the same figure every time and a change to one is a change worth looking at.

Value

An sf data frame of polygons in WGS84.

Details

The values are made up, but not arbitrarily: each is shaped like the quantity it stands for, because the point of the fixture is to exercise the scales.

density

Skewed hard, most cells near zero, a few carrying most of the total – which is what makes a linear ramp useless and is the case surface_scale() exists for.

cv

Rising where density falls, as a coefficient of variation does: the model is least certain where it saw least.

mess

Mostly positive with a novel corner, so it diverges around a zero that means something.

occupancy

On [0, 1], for map_probability().

residual

Centred on a non-zero mean, which is the case that breaks a diverging scale centred on zero.

grid_id

A cell identifier, for exercising the join in as_map_data().

Examples

grid <- example_grid()
head(sf::st_drop_geometry(grid))
#>   grid_id     density        cv      mess occupancy  residual
#> 1       1 0.009878606 0.5614851 -7.785698 0.3145203 0.8803216
#> 2       2 0.001922370 0.5210795 -6.429409 0.3271094 1.8712034
#> 3       3 0.004958808 0.5097867 -1.471500 0.3812665 2.2532980
#> 4       4 0.006967122 0.5160391  2.156948 0.4320310 0.1539027
#> 5       5 0.006013330 0.4959027 -5.118395 0.3532427 1.0915647
#> 6       6 0.003623981 0.4909970 -1.877589 0.4942128 1.6331130