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Quickstart

This walkthrough takes a raw ring-width file all the way to a crossdated site chronology. It uses ca533.rwl (Campito Mountain bristlecone pine), one of the classic dplR/ITRDB example collections. Every code block shows real dplPy output.

1. Load ring widths

import dplpy as dpl

rwl = dpl.readers("ca533.rwl", header=True)

ca533.rwl successfully extracted as rwl file with 34 series covering the period from 626 to 1983

readers returns a pandas DataFrame indexed by year, one column per series:

rwl.shape          # (1358, 34)  -> 1358 years, 34 series

Raw ring widths and sample depth for ca533

2. Inspect the data

dpl.stats(rwl).head(3)

   series  first  last  year   mean  median  stdev   skew  kurtosis   gini    ar1
1  CAM011   1530  1983   454  0.440    0.40  0.222  1.029     1.102  0.273  0.696
2  CAM021   1433  1983   551  0.424    0.40  0.185  0.946     1.110  0.237  0.701
3  CAM031   1356  1983   628  0.349    0.29  0.214  0.690    -0.366  0.341  0.808

3. Detrend (standardize)

Remove each series' biological growth trend to produce ring-width index (RWI) series. The default is a smoothing spline:

rwi = dpl.detrend(rwl, fit="spline")

See Detrending & standardization for the other curves (ModNegExp, ModHugershoff, Mean, AgeDepSpline) and the rcs, ssf, ads, and powt methods.

4. Build a chronology

Average the detrended series into a site chronology. By default this is a Tukey's-biweight robust mean with a sample-depth column:

crn = dpl.chron(rwi)
crn.tail(3)

           std  samp_depth
Year
1981  1.252329          21
1982  1.362052          21
1983  1.314605          21

Standard chronology for ca533

For AR-modelled or variance-stabilized chronologies, see Building chronologies.

5. Crossdate

xdate correlates each series, segment by segment, against a leave-one-out master to flag possible dating problems. It returns a dictionary of per-segment correlations and flags:

result = dpl.xdate(rwl)          # dplR-faithful default
result["seg_corr"]               # per-series, per-segment correlations

For a COFECHA-style run and a full formatted report, use the COFECHA preset and xdate_report:

report = dpl.xdate_report("ca533.rwl", preset="COFECHA")

The Crossdating & COFECHA guide covers flags, segment settings, the COFECHA emulation, and dating floating series with xdate_floater.

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