R: Bivariate Linear Interpolation

linearInterp {fBasics} | R Documentation

## 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)

### 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.

### 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"`.

### See Also

`akimaInterp`, and `krigeInterp`.

### Examples

    ## linearInterp -
       # Linear Interpolation:
       if (require(akima)) {
         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)
       }

[Package fBasics version 3042.89 Index]