# interpolate: Interpolation In phonTools: Tools for Phonetic and Acoustic Analyses

## Description

Piece-wise cubic or linear spline interpolation.

## Usage

 ```1 2``` ```interpolate (y, x = 1:length(y), steps = 20, increment = -1, show = FALSE, type = 'cubic', ...) ```

## Arguments

 `y` A vector of 'knots', between which the function will interpolate points. `x` The 'x' coordinates corresponding to each knot. If not specified, the knots are assumed to be equally spaced. `steps` The number of interpolating steps between each knot. Increasing this number will result in a smoother interpolation. If the knots are not equally spaced along the x-axis, the interpolated points will not be equally spaced across the entire curve. `increment` If this is greater than 0, interpolated points are separated along the x-axis by this value. Note that if the knot locations are not multiples of this increment, there will be irregularities in the spacing of the interpolated points. `show` If TRUE, the result of the interpolation is shown in a plot. `type` If 'cubic', a natural cubic spline interpolation is performed. If 'linear', a linear interpolation is performed. `...` Additional arguments are passed to the internal call of plot() if show = TRUE.

## Details

By default, this function performs a 'natural' cubic spline interpolation between the points provided by the user. Optionally, a linear interpolation between the points may be carried out.

## Value

A dataframe with columns corresponding to the x and y dimensions of the interpolated points is returned.

 `x` The x-axis coordinates of the interpolated points. `y` The y-axis coordinates of the interpolated points.

## Author(s)

Santiago Barreda <sbarreda@ucdavis.edu>

## References

http://en.wikipedia.org/wiki/Spline_interpolation

## Examples

 ```1 2 3 4 5 6``` ```## generate ten random points y = rnorm (10, 0, 5) interpolate (y, show = TRUE) ## plot a cubic interpolation linear = interpolate (y, type = 'linear') ## and compare to a linear interpolation lines (linear, col = 2) ```

phonTools documentation built on May 1, 2019, 6:26 p.m.