Coordinates and values, from whatever you have

Every interpolation function here takes the same thing: places, and a value at each place. This is what turns the various ways of expressing that into one matrix of coordinates and one vector of values.

Usage

xyz_input(x, value = NULL)

Arguments

x

coordinates: a matrix, a data frame, or anything wk handles

value

one value per coordinate, or NULL to use the z of x

Value

A list of xy (a two column matrix), value, and crs.

Details

A value can arrive two ways, and they are the same thing said differently: as a separate value argument, or as the z of three dimensional coordinates. Barycentric interpolation really is treating the value as a height above the plane, so wk::xyz() input is not an abuse of notation here, it is the notation. For kriging or a GAM it would be, which is why value exists too.

Objects from wk and sf go through wk::wk_coords(), which also carries their coordinate reference system across. A plain matrix or data frame is read by position: first column x, second y, third z if present. wk::as_xy() is deliberately not used for those, because it refuses to guess at column names, and Lon/Lat is exactly what real data is called.

Examples

xyz_input(cbind(1:3, 4:6), c(10, 20, 30))
#> $xy
#>      [,1] [,2]
#> [1,]    1    4
#> [2,]    2    5
#> [3,]    3    6
#> 
#> $value
#> [1] 10 20 30
#> 
#> $crs
#> NULL
#> 

## z is the value
xyz_input(cbind(1:3, 4:6, c(10, 20, 30)))
#> $xy
#>      [,1] [,2]
#> [1,]    1    4
#> [2,]    2    5
#> [3,]    3    6
#> 
#> $value
#> [1] 10 20 30
#> 
#> $crs
#> NULL
#> 

## and the crs comes along
xyz_input(wk::xyz(1:3, 4:6, c(10, 20, 30), crs = "EPSG:4326"))$crs
#> [1] "EPSG:4326"