astrochron (version 1.4)

mwin: Determine 'dynamic moving window' for stratigraphic series, adjusting for changing sample density to maintain a window of constant duration

Description

Determine start and end points for a moving window of fixed duration (e.g. 500 kiloyears). The dynamic window allows for adjustment of the number of data points in the window, so it has a constant duration in time or space.

Usage

mwin(dat,win,conv=1,verbose=T)

Value

A data frame containing: Starting index for window, Ending index for window, Location (average), Location (center), Location (midpoint)

Arguments

dat

Your data frame containing stratigraphic data; any number of columns (variables) are permitted, but the first column should be a location identifier (e.g., depth, height, time).

win

Moving window size in units of space or time.

conv

Convention for window placement: (1) center each window on a stratigraphic level in 'dat' (DEFAULT), (2) start with the smallest location datum in 'dat', (3) start with the largest location datum in 'dat'. For options 2 and 3, the center of the window will not necessarily coincide with a measured stratigraphic level in 'dat', but edges of the data set are better preserved.

verbose

Verbose output? (T or F)

Details

This algorithm steps forward one stratigraphic datum at a time. The output consists of:

Average = this is the average of the depth/time values in the given window.

Center = this is the center of the 'win' size window.

Midpoint = this is midpoint between first and last observation in the window (for unevenly sampled data this is typically less than than the size of 'win').

Examples

# generate some noise
ex1 <- ar1(npts=50,dt=1)

# jitter sampling times
ex1[1]=ex1[1]+rnorm(50,sd=3)
# sort 
ex1 = ex1[order(ex1[,1],na.last=NA,decreasing=FALSE),]

# run mwin
mwin(ex1,win=10)