R: From interp() Result, Produce 3-column Matrix

interp2xyz {akima} | R Documentation

## From interp() Result, Produce 3-column Matrix

### Description

From an `interp()` result, produce a 3-column matrix or `data.frame` `cbind(x, y, z)`.

### Usage

    interp2xyz(al, data.frame = FALSE)

### Arguments

`al` | a `list` as produced from `interp()`.
`data.frame` | logical indicating if result should be data.frame or matrix (default).

### Value

a matrix (or data.frame) with three columns, called `"x"`, `"y"`, `"z"`.

### Author(s)

Martin Maechler, Jan.18, 2013

### See Also

`expand.grid()` is the “essential ingredient” of `interp2xyz()`.

`interp`.

### Examples

    data(akima)
    ak.spl <- with(akima, interp(x, y, z, linear = FALSE,
                                 xo= seq(0,25, length=100),
                                 yo= seq(0,20, length= 96)))
    str(ak.spl)# list (x[i], y[j], z = <matrix>[i,j])

    ## Now transform to simple  (x,y,z)  matrix / data.frame :
    str(am <- interp2xyz(ak.spl))
    str(ad <- interp2xyz(ak.spl, data.frame=TRUE))
    ## and they are the same:
    stopifnot( am == ad | (is.na(am) & is.na(ad)) )

[Package akima version 0.6-2 Index]