rmf_interpolate: Interpolation of points on a rmf_2d/3d/4d_array

In rogiersbart/RMODFLOW: Pre- and post-processing of MODFLOW files

Interpolation of points on a rmf_2d/3d/4d_array

Description

Interpolation of points on a rmf_2d/3d/4d_array

Usage

rmf_interpolate(...)

## S3 method for class 'rmf_2d_array'
rmf_interpolate(
  array,
  dis,
  xout,
  yout,
  obj = NULL,
  method = "linear",
  outside = "nearest",
  prj = rmf_get_prj(dis),
  mask = array * 0 + 1
)

## S3 method for class 'rmf_3d_array'
rmf_interpolate(
  array,
  dis,
  xout,
  yout,
  zout,
  obj = NULL,
  method = "linear",
  outside = "nearest",
  prj = rmf_get_prj(dis),
  mask = array * 0 + 1
)

## S3 method for class 'rmf_4d_array'
rmf_interpolate(
  array,
  dis,
  xout,
  yout,
  zout,
  tout,
  obj = NULL,
  method = "linear",
  outside = "nearest",
  time = "step",
  prj = rmf_get_prj(dis),
  mask = array(1, dim = dim(array)[1:3])
)

Arguments

array	numeric rmf_2d/3d/4d_array
dis	RMODFLOW dis object
xout	x coordinates of points to interpolate to
yout	y coordinates of points to interpolate to
obj	sf or sfc point or multipoint object to obtain the point locations from. Overrides xout, yout and zout. Needs to be of XYZ dimension when array is 3d or 4d.
method	interpolation method. Possible methods are 'nearest' for nearest-neighbor or 'linear' (default) for bi/trilinear interpolation.
outside	'nearest' or 'drop'. Defines how interpolated points outside the convex hull described by the cell nodes should be handled for method = 'linear'. 'nearest' (default) sets the values equal to the nearest nodal value, 'drop' sets them to NA.
prj	RMODFLOW prj object
mask	a 2d array when array is 2d or a 3d array when array is 3d or 4d that can be coerced to logical. Used to set inactive cells to NA. Defaults to all cells active.
zout	z coordinates of points to interpolate to when the array is 3d or 4d.
tout	time instances to interpolate to when the array is 4d. Either as a fractional time step or as total simulated time, depending on the time argument.
time	either 'step' (default) or 'totim'. Defines if tout is a time step fraction (i.e. index for the 4th dimension) or the absolute time. If totim, the array should have a totim attribute, e.g. as returned from rmf_read_head

Details

Users must make sure that the projection of xout, yout, zout or obj are the same as the one described by the prj argument. Function assumes the 2d array is not a cross-section. Consider using a 3d array if the vertical dimension is of any concern. Extrapolation is not supported: values outside the grid are set to NA. Values inside the grid but outside the convex hull described by the cell nodes depend on the 'outside' argument when method = 'linear'.

Interpolation of a point on a 4d array is performed by 3d interpolation at the nearest time steps followed by a interpolation of the obtained values using the specified method.

Value

a vector with the interpolated values for each point.

Examples

dis <- rmf_create_dis()
n <- 50
xout <- runif(n, min = -10, max = 1010)
yout <- runif(n, min = -10, max = 1010)
zout <- runif(n, min = -31, max = 1)

# 2d
array <- rmf_create_array(1:prod(dis$nrow, dis$ncol), dim = c(dis$nrow, dis$ncol))

rmf_interpolate(array, dis, xout, yout)
rmf_interpolate(array, dis, xout, yout, outside = 'drop')
rmf_interpolate(array, dis, xout, yout, method = 'nearest')

# 3d
array <- rmf_create_array(1:prod(dis$nrow, dis$ncol, dis$nlay), dim = c(dis$nrow, dis$ncol, dis$nlay))

rmf_interpolate(array, dis, xout, yout, zout, outside = 'drop')

pts <- sf::st_sfc(list(sf::st_point(c(150, 312, -12.5)), sf::st_point(c(500, 500, -22)), sf::st_point(c(850, 566, -16.3))))
rmf_interpolate(array, dis, obj = pts)

# 4d
array <- rmf_create_array(1:prod(dis$nrow, dis$ncol, dis$nlay, 4), dim = c(dis$nrow, dis$ncol, dis$nlay, 4))
attr(array, 'totim') <- c(100, 200, 500, 780)

tout <- runif(n, min = 0.85, max = 4.2) # tout as fractional time step
rmf_interpolate(array, dis, xout, yout, zout, tout)

tout <- runif(n, min = 90, max = 800) # tout as total time
rmf_interpolate(array, dis, xout, yout, zout, tout, time = 'totim')
 

rogiersbart/RMODFLOW documentation built on Jan. 14, 2023, 4:21 a.m.