sortedXyData {nls} | R Documentation |

## Create a sortedXyData object

### Description

This is a constructor function for the class of `sortedXyData`

objects. These objects are mostly used in the `initial`

function for a self-starting nonlinear regression model, which will be
of the `selfStart`

class.

### Usage

sortedXyData(x, y, data)

### Arguments

`x` |
a numeric vector or an expression that will evaluate in
`data` to a numeric vector |

`y` |
a numeric vector or an expression that will evaluate in
`data` to a numeric vector |

`data` |
an optional data frame in which to evaluate expressions
for `x` and `y` , if they are given as expressions |

### Value

A `sortedXyData`

object. This is a data frame with exactly
two numeric columns, named `x`

and `y`

. The rows are
sorted so the `x`

column is in increasing order. Duplicate
`x`

values are eliminated by averaging the corresponding `y`

values.

### Author(s)

Jose Pinheiro and Douglas Bates

### See Also

`selfStart`

, `NLSstClosestX`

,
`NLSstLfAsymptote`

, `NLSstRtAsymptote`

### Examples

data( DNase )
DNase.2 <- DNase[ DNase$Run == "2", ]
sortedXyData( expression(log(conc)), expression(density), DNase.2 )