Options for different transformations — geo

When using geo_transform the transformation options must be passed as named list appropriate to the transformation. These functions are used to generate such named lists.

Usage

geo_opts_points(
  points,
  method = c("bilinear", "nearest", "bicubic"),
  mask = NULL,
  force = FALSE,
  weights = NULL,
  keep_weights = FALSE
)

geo_opts_regrid(
  new_grid,
  method = c("bilinear", "nearest", "bicubic"),
  mask = NULL,
  new_mask = NULL,
  weights = NULL,
  keep_weights = FALSE
)

geo_opts_subgrid(i1, i2, j1, j2)

geo_opts_zoom(centre_lon, centre_lat, length_x, length_y)

geo_opts_xsection(
  p1,
  p2,
  n = 100,
  method = c("bilinear", "nearest", "bicubic"),
  weights = NULL,
  keep_weights = FALSE
)

geo_opts_upscale(factor, method = "mean", downsample_location = "bottom_left")

Arguments

points: A data frame of geographic points to which to interpolate the gridded data. The data frame must include the columns "SID" for a unique id for the point, "lon" for the longitude of the point in decimal degrees and "lat" for the latitude of the point in decimal degrees. The data frame can contain other columns, which will be retained in the output.
method: The interpolation method. Can be "nearest" for nearest neighbour, "bilinear", or "bicubic." The default is "bilinear". For geo_upscale, can be any function that summarises a vector to a single value and can found with match.fun, the default being "mean". A further option is "downsample", dwhich is described in the argument for downsample_location.
mask: A mask to prevent grid points being used in the interpolation. Should be on the same grid as x and grid points with values of 0 or FALSE will be masked from the interpolation.
force: For interpolations that include a mask, it is possible that a point will be surrounded by 4 masked points. In this case the mask will be ignored and all 4 points used in the interpolation (the default). Set force = TRUE to force the mask to be applied and set the interpolated to NA.
weights: Pre-computed weights for the interpolation. Should be the output from the appropriate geo_weights function.
keep_weights: Whether to keep weights in the output. If set to TRUE, the return object will have a "weights" attribute.
new_grid: A geofield or geodomain on the grid that x should be regridded to. define_domain can be used to define a new geodomain.
new_mask: A geofield on the same grid as new_grid with grid points that should not be interpolated to set to 0 or FALSE.
i1: The x index of the western side of the sub domain.
i2: The x index of the eastern side of the sub domain.
j1: The y index of the southern side of the sub domain.
j2: The y index of the northern side of the sub domain.
centre_lon: The longitude in decimal degrees of the centre of the zoomed grid.
centre_lat: The latitude in decimal degrees of the centre of the zoomed grid.
length_x: The number of grid squares from west to east of the zoomed grid. If an even number is used, it will be extended by 1 since the zoomed grid should be centred on the grid square containing (centre_lat, centre_lon).
length_y: The number of grid squares from south to north of the zoomed grid. If an even number is used, it will be extended by 1 since the zoomed grid should be centred on the grid square containing (centre_lat, centre_lon).
p1: The geographic location in decimal degrees of the start of the section. Should be a vector of length 2 with the first value being the longitude and the second value the latitude.
p2: The geographic location in decimal degrees of the end of the section. Should be a vector of length 2 with the first value being the longitude and the second value the latitude.
n: The number of equally spaced points along the section. The default is 100.
factor: An integer by which to upscale the data. Can be of length 2 to achieve different upscaling in the x and directions.
downsample_location: When "downsample" is the chosen method, each pixel in the upscaled field is sampled from a pixel from the original field that is inside the upscaled pixel. The location of that pixel can be one of "bottom_left", "bottom_centre", "bottom_right", "left_centre", "centre", "right_centre", "top_right", "top_centre", "top_left" or "random".