Description Usage Arguments Details Value Author(s) See Also Examples

Calculate the area under the curve with a simple "trapezoid" algorithm and with a more elaborated spline approach. The curve must be given by vectors of xy-coordinates.

1 2 3 |

`x, y` |
the xy-points of the curve |

`method` |
The type of interpolation. Can be |

`from` |
The value from where to start calculating the area under the curve. Defaults to the smallest x value. Must not be smaller that that. |

`to` |
The value from where to end the calculation of the area under the curve. Defaults to the greatest x value. Must not be larger than that. |

`absolutearea` |
logical, determines whether negative
areas should be added to the total area under the curve. By
default the |

`subdivisions` |
an integer telling how many subdivisions should be used for integrate (for non-linear approximations). Ignored if |

`na.rm` |
logical, indicating whether |

`...` |
additional arguments passed on to approx (for linear approximations). In particular rule can be set to determine how values outside the range of x is handled. |

If method is set to `"trapezoid"`

then the curve is formed by connecting all points by a direct line (composite trapezoid rule). If `"step"`

is chosen then a stepwise connection of two points is used in the sense that the y-value of the lower x-value is used for the range up to the next x-point.

For area under a spline interpolation,
`AUC()`

uses the `splinefun()`

function in combination with `integrate()`

to
calculate a numerical integral.

The `AUC()`

function can handle unsorted time
values (by sorting `x`

), missing observations, ties for the `x`

values (by ignoring duplicates), and integrating over
part of the area or even outside the area.

numeric value of the area under the curve.

Andri Signorell <andri@signorell.net>, spline part by Claus Ekstrom <claus@rprimer.dk>

1 2 3 4 5 6 7 8 9 10 11 | ```
AUC(x=c(1,3), y=c(1,1))
AUC(x=c(1,2,3), y=c(1,2,4), method="trapezoid")
AUC(x=c(1,2,3), y=c(1,2,4), method="step")
plot(x=c(1,2,2.5), y=c(1,2,4), type="l", col="blue", ylim=c(0,4))
lines(x=c(1,2,2.5), y=c(1,2,4), type="s", col="red")
x <- seq(0, pi, length.out=200)
AUC(x=x, y=sin(x))
AUC(x=x, y=sin(x), method="spline")
``` |

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