R: Calculate NET

net {dplR} | R Documentation

## Calculate NET

### Description

Computes the NET parameter for a set of tree-ring records or other time-series data.

### Usage

    net(x, weights = c(v = 1, g = 1))

### Arguments

`x` | A `matrix` or `data.frame` with at least two rows and two columns containing `numeric` data. The rows should represent a sequence of sampling points with uniform intervals (e.g. a range of years), but this is not checked. Each column is a time-series spanning either the whole time range or a part of it.
`weights` | A `numeric` vector with two elements. Normally, variation (`"v"`) and Gegenläufigkeit (`"g"`) contribute to NET with equal weight. It is possible to use different weights by setting them here. The names of the vector are matched to `c("v", "g")` (see ‘Examples’). If no names are given, the first element is the weight of variation.

### Details

This function computes the NET parameter (Esper et al., 2001). The overall NET is an average of all (non-`NA`) yearly values NET[j], which are computed as follows:

NET[j] = v[j] + (1-G[j])

The yearly variation v[j] is the standard deviation of the measurements of a single year divided by their mean. Gegenläufigkeit 1-G[j] is based on one definition of Gleichläufigkeit G[j], similar to but not the same as what `glk` computes. Particularly, in the formula used by this function (Esper et al., 2001), simultaneous zero differences in two series are not counted as a synchronous change.

The weights of v[j] and 1-G[j] in the sum can be adjusted with the argument `weights` (see above). As a rather extreme example, it is possible to isolate variation or Gegenläufigkeit by setting one of the weights to zero (see ‘Examples’).

### Value

A `list` with the following components, in the same order as described here:

`all` | a `numeric` vector containing NET[j]. Row names of `x` (if any) are copied here.
`average` | a `numeric` value NET, the average of the `"all"` vector (`NA` values removed).

### Author(s)

Mikko Korpela

### References

Esper, J., Neuwirth, B., and Treydte, K. (2001) A new parameter to evaluate temporal signal strength of tree-ring chronologies. Dendrochronologia, 19(1), 93–102.

### Examples

    library(utils)
    data(ca533)
    ca533.rwi <- detrend(rwl = ca533, method = "ModNegExp")
    ca533.net <- net(ca533.rwi)
    tail(ca533.net$all)
    ca533.net$average
    ## Not run:
    ## Isolate the components of NET
    ca533.v <- net(ca533.rwi, weights=c(v=1,0))
    ca533.g <- net(ca533.rwi, weights=c(g=1,0))

    ## End(Not run)

[Package dplR version 1.7.2 Index]