net: Calculate NET
In dplR: Dendrochronology Program Library in R

Description Usage Arguments Details Value Author(s) References Examples

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

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

`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.

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’).

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).

Mikko Korpela

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.

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)