fBasics (version 4021.93)

linearInterp: Bivariate Linear Interpolation

Description

Bivariate Linear Interpolation. Two options are available gridded and pointwise interpolation.

Usage

linearInterp(x, y = NULL, z = NULL, gridPoints = 21,
    xo = seq(min(x), max(x), length = gridPoints),
    yo = seq(min(y), max(y), length = gridPoints))
    
linearInterpp(x, y = NULL, z = NULL, xo, yo)

Value

linearInterp

returns a list with at least three entries, x, y

and z. Note, that the returned values, can be directly used by the persp and contour 3D plotting methods.

linearInterpp

returns a data.frame with columns "x", "y", and "z".

Arguments

x, y, z

for linearInterp the arguments x and y are two numeric vectors of grid pounts, and z is a numeric matrix or any other rectangular object which can be transformed by the function as.matrix into a matrix object. For linearInterpp we consider either three numeric vectors of equal length or if y and z are NULL, a list with entries x, y, z, or named data frame with x in the first, y in the second, and z in the third column.

gridPoints

an integer value specifying the number of grid points in x and y direction.

xo, yo

for linearInterp two numeric vectors of data points spanning the grid, and for linearInterpp two numeric vectors of data points building pairs for pointwise interpolation.

See Also

akimaInterp, and krigeInterp.

Examples

## linearInterp -
   # Linear Interpolation:    
   if (requireNamespace("interp")) {
     set.seed(1953)
     x = runif(999) - 0.5
     y = runif(999) - 0.5
     z = cos(2*pi*(x^2+y^2))
     ans = linearInterp(x, y, z, gridPoints = 41)
     persp(ans, theta = -40, phi = 30, col = "steelblue",
        xlab = "x", ylab = "y", zlab = "z")
     contour(ans)
   }