EPS-based chronology stripping after Fowler & Boswijk 2003.
strip.rwl(rwl, ids = NULL, verbose = FALSE, comp.plot = FALSE,
legacy.eps = FALSE)
The functions returns a data.frame of raw tree-ring widths,
where series that do not contribute to an overall improvement in
EPS are left out.
a data.frame of raw tree-ring widths series, such as
that produced by read.rwl or read.fh
an optional data.frame with column one named
"tree" giving a numeric ID for each tree and
column two named "core" giving a numeric ID
for each core. This is passed on to rwi.stats. See
its manual for the meaning of the default value NULL and more
information.
logical flag, indicating if the EPS
calculated at each step and other details should be printed on the
console during the chronology stripping process
logical flag, indicating if a diagnostic plot
with year-wise stripped and unstripped EPS should be drawn
(see details below)
logical flag, indicating if the EPS
will be calculated with rwi.stats (FALSE, the default)
or rwi.stats.legacy (TRUE)
Christian Zang. Patched and improved by Mikko Korpela.
The EPS-based chronology stripping is implemented after
Fowler & Boswijk 2003: First, all series are standardized using a
double detrending procedure with splines and frequency cutoffs of 50%
at 20 and 200 years. Then, EPS is calculated for the
chronology including all (remaining) series. In each iteration, the
algorithm calculates leave-one-out EPS values, and the
series whose removal increases overall EPS the most is
discarded. This is repeated until no further increase in
EPS is gained by discarding a single series. The procedure
is then repeated in the opposite direction, i.e., the reinsertion of
each previously removed series into the data.frame is
considered. In each iteration, the series (if any) whose reinsertion
increases EPS the most is reinserted. As a last step,
EPS is calculated for each year of the stripped and original
chronology including all series. If comp.plot is set to
TRUE, a diagnostic plot is shown for the year-wise comparison.
When verbose output is chosen, the EPS values for all leave-one-out (or back-in) chronologies are reported. If discarding or re-inserting a single series leads to an improvement in EPS, this series is marked with an asterisk.
Fowler, A. and Boswijk, G. (2003) Chronology stripping as a tool for enhancing the statistical quality of tree-ring chronologies. Tree-Ring Research, 59(2), 53–62.
rwi.stats
library(utils)
data(anos1)
anos1.ids <- read.ids(anos1, stc = c(4, 3, 1))
srwl <- strip.rwl(anos1, ids = anos1.ids, verbose = TRUE)
tail(srwl)
Run the code above in your browser using DataLab