approxTime {simecol} | R Documentation

## Linear Interpolation with Complete Matrices or Data Frames

### Description

Return a data frame, matrix or vector which linearly interpolates data from a given matrix or data frame.

### Usage

    approxTime(x, xout, ...)
    approxTime1(x, xout, rule = 1)

### Arguments

`x` | a matrix or data frame with numerical values giving coordinates of points to be interpolated. The first column is interpreted as independend variable (e.g. time), the remaining columns as dependend variables.
`xout` | a vector (or single value for `approxTime1`) of independend values specifying where interpolation has to be done.
`rule` | an integer describing how interpolation is to take place outside the interval [min(x), max(x)]. If `rule` is 1 then `NA`s are returned for such points and if it is 2, the value at the closest data extreme is used.
`...` | optional parameters passed to `approx`.

### Details

The functions can be used for linear interpolation with a complete matrix or data frame. This can be used for example in the main function of an `odeModel` to get input values at a specified time `xout`. The version `approxTime1` is less flexible (only one single value for xout and only linear interpolation) but has increased performance. Both functions are faster if `x` is a matrix instead of a data frame.

### Value

`approxTime` returns a matrix resp. data frame of the same structure as `x` containing data which interpolate the given data with respect to `xout`. `approxTime1` is a performance optimized special version with less options than the original `approx` function. It returns an interpolated vector.

### See Also

`approxfun`

### Examples

    inputs <- data.frame(time = 1:10, y1 = rnorm(10), y2 = rnorm(10, mean = 50))
    input  <- approxTime(inputs, c(2.5, 3), rule = 2)

[Package simecol version 0.6-9 Index]