romsmap: Remap an object to the ROMS grid.

In mdsumner/angstroms: Tools for 'ROMS' the Regional Ocean Modeling System

Remap an object to the ROMS grid.

Description

Find the nearest-neighbour coordinates of x in the coordinate arrays of coords.

Usage

romsmap(x, ...)

## S3 method for class 'SpatialPolygonsDataFrame'
romsmap(x, coords, crop = FALSE, lonlat = TRUE, ...)

## Default S3 method:
romsmap(x, coords, crop = FALSE, lonlat = TRUE, ...)

## S3 method for class 'SpatialLinesDataFrame'
romsmap(x, coords, crop = FALSE, lonlat = TRUE, ...)

## S3 method for class 'SpatialPointsDataFrame'
romsmap(x, coords, crop = FALSE, lonlat = TRUE, ...)

Arguments

x	object to transform to the grid space, e.g. a Spatial object
...	unused
coords	romscoords RasterStack
crop	logical, if TRUE crop x to the extent of the boundary of the values in coords
lonlat	logical, if TRUE check for need to back-transform to longitude/latitude and do it

Details

The input coords is a assumed to be a 2-layer RasterStack or RasterBrick and using FNN::get.knnx() the nearest matching position of the coordinates of x is found in the grid space of coords. The motivating use-case is the curvilinear longitude and latitude arrays of ROMS model output.

No account is made for the details of a ROMS cell, though this may be included in future. We tested only with the "lon_u" and "lat_u" arrays.

Value

input object with coordinates transformed to space of the coords

Note

Do not use this for extraction purposes without checking the output, this is best used for exploration and visualization. Re-mapping ROMS data is better done by looking up the coords_points within spatial objects, and transferring via the grid index.

Examples

library(raster)
ant_ice_coords <- romsmap(antarctica, ice_coords)
raster::image(ice_fake, col = c("transparent", hcl.colors(24)), asp = 1)
sp::plot(ant_ice_coords, add = TRUE)

mdsumner/angstroms documentation built on Oct. 11, 2024, 10:36 p.m.